Tour to Neocene
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Translated by Jackson Orzekowski
Edited by Timothy Morris and Pavel Volkov
Meganesia represents a continent located in the southern hemisphere
sandwiched between the Pacific Ocean in the east and the Indian Ocean in the
west. In the human epoch, depending on changes in sea level during the ice age,
the whole landmass appeared and broke for several times. When Homo sapiens first
appeared on this land during the ice age, the continent was whole. Later, as
the massive glaciers of the northern hemisphere began to melt, sea levels rose,
and the united landmass separated into the continent of Australia and the island
of New Guinea. At the same time other forces were at work in the land down under,
forces occurring deep beneath the thickness of the earth's crust. The lithospheric
plate, on which Australia and New Guinea rested, slowly moved north towards
the equator. The northern edge of this lithospheric plate rose slightly, and
this had a great influence on the geography of the continent. In the south,
the large shallow Eyre Gulf penetrated far inland. In the north, the geography
of the mainland has undergone even more significant changes. Australia and New
Guinea have reunited, reforming the single landmass of Meganesia. This has caused
the Arafura Sea to become shallower, while the water in this sea has become
greatly desalinated. In the Neocene, its connection with the ocean has weakened
significantly, being maintained only through a series of small channels located
in a vast belt of mangrove forests and swamps. The nearby Gulf of Carpentaria
became separated from the ocean even earlier than the Arafura Sea, and by the
Neocene had undergone even more dramatic changes. The water of the gulf has
become even more desalinated than in Arafura Lake, and it is surrounded by extensive
wetlands and mangrove forests. As a result, Gulf Carpentaria has transformed
into Lake Carpentaria.
In the deep layers of Lake Carpentaria, the water is still slightly brackish
– it is a legacy of this reservoir's maritime past. Freshwater descendants of
marine animals also live here: stingrays, blowfishes, pipefishes and silversides.
Some of them live only in the depths of the lake, staying in layers of saltier
water, but most still inhabit shallow water, where the water is rich in oxygen,
and life is plentiful and diverse. A significant amount of organic remains enters
the depths of Lake Carpentaria; therefore the darkest deep-water parts of the
lake are poor in life – oxygen is in obvious deficit here since it is spent
on decay. From time to time, bubbles of methane and hydrogen sulfide burst out
of the silt strata, quickly floating up and imploding on the surface. Someday
the rich and diverse world of Lake Carpentaria will perish – the basin of the
lake will be filled with organic remains, petrifying over time. This will turn
the lake into a shallow swamp, split into many small bodies of water, before
eventually causing Lake Carpentaria to disappear completely, with a dense tropical
forest growing in its place.
However, these changes are still millions of years away. In the present, the
lake prospers, the productivity of its upper layers are enough to support a
diverse life, from shallow water down to the gloomy depths. The upper layers
of lake water have a green tint due to an abundance of multiplying microscopic
algae, which serve as food for planktonic crustaceans. Forests of underwater
plants grow in shallow waters. At some distance from the coast, eel grass of
enormous size form dense sod, resembling thickets of seaweed. Tuberous plants
flourish in the coastal zone, including aponogetons and water lilies. Their
leaves form especially dense thickets opposite the swampy shores, where herbivores
have fewer opportunities to descend into the water for feeding. At sandbanks,
tuberous plants recede further from the coast, and the leaves of the water lilies
sway on the surface of the lake over two to three meters deep. In some places,
the shores of Lake Carpentaria are overgrown with tall reeds, and the soil is
riddled with their thin branching rhizomes.
Plants serve as food for a wide variety of animals – from crustaceans to large
mammals. These herbivores are in turn preyed upon by a host of predatory organisms,
some of them being huge.
In the water, among thickets of pondweed with long, strong stems, a snake’s
skin sways. Judging by its preservation, this snake had shed its skin recently.
Obviously, the snake swam intentionally into the thicket of pondweed so that
the friction of the stalks, which are resistant to tearing, helped to shed its
exfoliated corneous epidermis. Due to the fact that the snake molted in the
water, its skin did not break from its own weight and has preserved the imprint
of the appearance of the former owner. At the front end, a characteristic pattern
of shields covering the head is noticeable. Among them, two wide transparent
windows formed by a smooth horny film are clearly distinguishable. During life,
they covered the eyes of the reptile. The discarded snakeskin sways in the waves,
catching one end of the edge of the thicket. Perhaps in some other case it might
seem like something ordinary, except for the size of the slough – its length
is about ten meters.
The skin belonged to the most unusual and dangerous inhabitant of Lake Carpentaria
– a gigantic python species that switched to an aquatic lifestyle. This is the
eingana, the top predator of the lake. Moreover, the shed skin, swaying in the
water, belongs to a young individual. An adult of this species can reach a length
of twenty meters with a body thickness of about a meter. Such a giant has nothing
to fear, and an adult eingana enjoys all the rights and privileges of being
the supreme predator of the ecosystem.
Lake Carpentaria and the surrounding marshes are located in an area of heavy
rainfall, and rivers are constantly flowing from the mountains, ensuring the
stability of the water level in the lake. The shores of the lake and swamps
are overgrown with tropical rainforest, and these places are literally boiling
with life. The existence of many forest dwellers depend on the lake. Small forest
birds arrive at the watering hole, behaving cautiously near the water. From
time to time, flocks of colorful parrots appear on the shores of the lake, filling
the vicinities with their loud calls.
A bird’s-eye view opens up a wonderful perspective of the lake, the waters of
which have a greenish tint, especially clear under the rays of the morning sun.
In the shallow coastal waters, water lilies grow, the thickets of which are
abundantly colored with white, yellow and pink flowers. Against the background
of the sandy bottom, thickets of pondweed stand out in darker spots. Schools
of fish form dark spots changing their shape the whole time. If something scares
them away, the school sharply changes its direction of movement, its sides shining
in the rays of the sun.
It seems like a heap of smooth gray stones lays in the shallows near the coast.
However, these “stones” move slowly along the coast, moving towards and away
from one another. These things belong to the number of the largest local herbivores
called bovipotamuses. Their presence on the territory of Meganesia is a result
of human influence to the nature of the Earth. Bovipotamuses are the aquatic
descendants of Asiatic water buffaloes. Marsupials cannot master aquatic habitats
in full degree because of the brood pouch, where joeys are carried for a long
time. Buffaloes, which are placental mammals, faced competition from marsupials
and descendants of camels (also introduced by humans) in drier habitats, but
found themselves practically without competition from the other herbivorous
mammals of the continent when it came to living in lakes and swamps. The further
specialization to living a semi-aquatic lifestyle has led to the emergence of
bulky bovipotamuses, excellent swimmers and divers, and also tireless vegetation
devourers. Maybe, without the insatiable appetite of bovipotamuses, the lake
coasts would be overgrown heavily with impenetrable thickets of marsh plants.
These huge herbivores thin out these plants, making these coastal thickets comfortable
for life of other animals.
Bovipotamuses are perfectly adapted to life in the water. The skin of these
mammals is almost hairless – only a thick mane of elongated hair grows on the
neck along the spine and the tip of the tail is crowned with a tuft. On land,
bovipotamus looks clumsy: this beast is of a stocky build, with a massive body,
a large head and relatively short legs. But under the water, these animals literally
transform: their bodies slide in the water easily and even gracefully. Wide
hooves that look awkward when walking on the land now rake in the water, the
animal swimming and diving with ease. Under water, the hooves expand and the
extensible skin that ties the animal’s toes together helps it paddle through
the water. Bovipotamuses, satiated after a night of feeding on the shore spend
the morning at rest, basking in the water. The whole herd of them lies at a
shallow depth, barely touching the bottom of the lake with their hooves. Bovipotamus’
eyes and nostrils sit on the top of its flattened head, making them visible
on the surface even when the rest of its body is submerged. In large adults,
the neck and shoulders also protrude above the water. Their wet manes stick
to their skin in clumps, and small midges hover over them. Calves, which cannot
reach the bottom with their feet, plunge into the water deeper than the adults,
with only their heads sticking out on the surface of the water. Some of the
calves simply lay their head on the back of their mother and doze, lazily moving
their legs in their sleep. Adult animals ruminate slowly. Curiously, horns of
bovipotamus are relatively poorly developed – their bases are close together
and greatly expanded, forming something like a corneous helmet. This feature
helps them move through the forest, pushing apart the branches of the bushes
and protecting their eyes from wounds. In males, the ends of the horns are directed
to the sides, an in females, horns are shortened and represent simply small
pointed outgrowths directed down more often.
While bovipotamuses bask in the lake, they fail to notice an ominously writhing
shadow approaching them. An adult eingana, a snake about eighteen meters long,
is swimming along the coast, looking for a warmer place after a cool night.
It is a reptile, and warmth is important for its life. However, the snake is
not hunting. The huge reptile does not hide its presence: it emerges to the
surface and pokes its head out of the water. Leathery valves open, and eingana
exhales air in a strident whistle, and then inhales a breath of fresh air.
Bovipotamuses have keen hearing, so the animals, having barely heard the noise
of the breathing reptile, instantly wake up. They do not see the huge snake,
but the sound of breathing of eingana is associated with danger even among these
simple-minded giants. Panic immediately takes hold of the herd, the adult and
their calves rushing to the shore, causing a massive stampede. The adults bellow
in terror, while cubs, crushed by the sides of adults, moo in fright. As bovipotamuses
scramble ashore in a chaotic stampede, rising clouds of silt and sand from the
bottom with their hooves, turning the green water plants into crumbs and trampled
reeds. From there, they can get a better look at the cause of their panic –
a giant snake wriggling smoothly in the water among the clouds of silt. The
eingana is not hunting – if it were necessary, it would attack its prey from
under the water. Instead, the snake is busy with an equally important matter.
This is a pregnant adult female, and she needs to warm herself – it is an adult
female, and its many month long pregnancy comes to an end. Although the Eingana
is a descendant of pythons, it does not lay eggs, but gives birth to live young.
This is an inevitable consequence of its adaptation to life in the water – it
would be extremely difficult for large females to get out onto dry land to lay
eggs, and it would be even more difficult to protect the clutch from enemies
and take care of it. Viviparity and the transition to an aquatic lifestyle removed
the size limitation from this snake’s ancestors, and as a result, eingana has
turned into one of the Neocene’s largest reptiles.
The eingana female has long felt the movements of the babies in her belly. Now,
as her body heats up in the warm waters of the lake, the movements of the juveniles
in her belly become more active. It seems, it is a proper time for them to be
born.
Waves of muscle contractions run through the body of the giant reptile. The
body of the female eingana involuntarily bends, preparing to give birth to the
offspring. Finally, after another wave of muscle contractions, the first snakeling
escapes from the womb of the giant snake. At birth, it is still covered with
a thin film, penetrated with blood vessels, but in the very first seconds after
birth, juvenile breaks through it and leaves it, wriggling its entire body.
Its length at birth is already about two meters. Several small fish, attracted
by the smell of blood, rush in different directions when the newborn snake swims.
The young reptile emerges to the surface of the water and takes its first breath.
Following the first baby from the womb of the reptile, two more appear, one
after the other. Like their sibling, they cast off the embryonic membranes and
swim away. Within half an hour, the labor continues, the giant female eingana
giving birth to two dozen cubs. This is the maximum fertility of an adult reptile
of this species: the female is in top physical condition and has reached the
full potential inherent in its nature.
The babies try to leave their mother as soon as possible. Wriggling, they quickly
swim away and hide in the greenish water of the lake. The female, still in a
stressful state, pays no attention to them. But later, having recovered from
the stress and turning hungry after delivery, she will not hesitate to feed
on her own offspring. Cannibalism is not uncommon in eingana populations. Therefore,
young snakes of this species keep to the shallows, where adults rarely appear
and suitable prey is more abundant.
In some places near the shores, the surface of the lake is covered with patches
of floating plants. In the quiet shallow bays, ubiquitous duckweed grows, and
in areas facing open water, another plant thrives – a local variety of water
hyacinth (Eichornia), a descendant of a species introduced by humans. This plant
forms rather dense clouds of floating “islands” that dampen waves and serve
as a refuge for a variety of aquatic animals. Among the fluffy roots of water
hyacinths, fish and shrimp hide from enemies, and the surface of the plants
serves as a home for various invertebrates – mainly for insects. If the floating
“islands” of the water hyacinth are washed ashore, bovipotamuses will willingly
feed on them. To some extent, these animals restrain the growth of floating
vegetation. The water hyacinth carpets are so thick that small herons can walk
on them without falling through. These birds often use floating plants as a
convenient hunting ground.
The shallow areas of the lake are well lit and warm, and here the upper layer
of water acquires a greenish tint due to the microscopic algae developing in
the water. This is one of the components of the foundation of the food pyramid,
the top of which is crowned by the monstrous eingana. Due to their high rate
of reproduction, algae can provide food for a variety of invertebrates – small
cladocerans, rotifers and worms. Lacustrine plankton teems in the water, but
most of the creatures that make up it have a transparent body and are poorly
visible in the water. Only in the rays of the sun can one observe the tiny creatures
scurrying about in the water column. However, some of the lake’s inhabitants
do not need to see their food – they have a completely different way of feeding.
A shoal of small transparent creatures swims in the water column at a depth
of about half a meter. At first glance, they look like small fish, but upon
closer inspection, this similarity turns out to be deceiving. Their bodies are
covered with chitinous shells, they have developed antennae and several pairs
of articulated legs that perform various functions. This is another characteristic
inhabitant of Lake Carpentaria, the bristle-legged shrimp. The structure of
its legs is unusual for decapod crustaceans, and its lifestyle is clearly atypical
for Atyidae family to which it belongs. In the human epoch, related species
of Atyidae shrimps were large and heavy-built creatures that lived at the bottom
and among plants, filtering edible particles from the water using two pairs
of modified front legs. The ability of water filtering is preserved in the bristle-legged
shrimp, but the lifestyle of this creature is completely different. In due course
of evolution, it turned slimmer, and it allows this crustacean to populate the
water column and master feeding on the lake plankton.
Bristle-legged shrimps spend a significant part of their life filtering their
food. For this reason, they have two front pairs of walking legs modified into
a trapping apparatus. They are covered with numerous hairs, and the shrimp constantly
waves them rhythmically. Due to these movements, these shrimps can swim and
gather planktonic animals at the same time. From time to time, the shrimps scrape
off the accumulated food with their maxillipedes and swallow it.
The waters of Lake Carpentaria are slightly brackish – this is an evidence of
its past when the lake was a bay of saltwater. In the depths there are layers
of salt water, but the upper layer of water is heavily desalinated by rivers
and rainwater. Residual salinity is present here, but the amount of salt is
so low that it does not interfere with the growth of aquatic plants. And due
to that same salt, the offspring of many invertebrate species can develop successfully
in the water of the lake. Bristle-legged shrimps breed far from river mouths,
and planktonic larvae of this species develop in the water column. It is possible
that the shrimps themselves eat, along with other food, some of their own larvae
at the planktonic stage of development. But their fertility is high enough to
compensate for these and other losses, and their species thrives.
A school of bristle-legged shrimps feeds, slowly moving in the water column.
Shrimps keep their distance from one another, gathering plankton. In the shallows,
the water warms up and is well-illuminated, and it promotes the growth of unicellular
algae. Small invertebrates thrive here – rotifers, microscopic cladocerans and
insect larvae; therefore, shrimps have more than enough food for themselves.
However, they must be careful – a predator may appear from where it is least
expected.
An island of water hyacinth thickets floats on the surface of the water. This
plant constantly grows long sarments, on which plantlets develop. Therefore,
even a single plant can form a floating island of plants very soon. Long fluffy
roots hang down from it in the water column, among which fry of fish and juvenile
shrimps usually hide from predators. Feeling no danger, bristle-legged shrimps
continue feeding. From time to time, one or another shrimp changes its position
in the school and moves to a site richer in plankton. To do this, the crustacean
waves its third pair of walking legs. Unlike the first two pairs of legs, these
legs are wide and flat. In the ancestors of this species, they served for fixing
on the substrate, but in the bristle-legged shrimp, they turned to fins. With
several synchronous strokes of these legs, the shrimp swims to a new place,
after which it continues to feed. At rest, its swimming legs serve as stabilizers
– elevators and rudders.
While bristle-legged shrimp feed in peace, they fail to notice that they are
being watched. A different shrimp is hiding on the island of floating plants
among the roots. It does not feed on plankton but seeks more substantial prey.
It is a large barracuda prawn, about 25 centimeters long, a formidable predator
for its weight class. It does not chase its prey during the hunt, rather, it
relies on the accuracy of its strike, in which all its forces are put. An ambush
predator, it waits for prey of proper size to come within striking distance.
An islet of water hyacinth drifts on the water, driven by the wind. Bristle-legged
shrimps are oblivious to the danger and continue filtering the water. The barracuda
prawn is patient, waiting for a favorable set of circumstances only. As the
wind carries its shelter towards its target, it is possible for it to expect
for a success in hunting.
Barracuda prawn is a very distant relative of the bristle-legged shrimp and
belongs to a completely different shrimp family. Unlike bristle-legged shrimps,
this species is armed with strong claws, a cutting-edge weapon equipped with
a pointed spike. When prey gets into such claws, there is no hope for escape.
The barracuda prawn sees its prey and senses its movements with the help of
sensitive bristles growing on the antennae. It prepares to the attack and opens
its claws. Trying not to give itself away with unnecessary movement, the barracuda
prawn remains motionless. Only its large eyes on the stalks tremble slightly,
betraying its tension. Gripping the roots of the water hyacinth, the shrimp
hangs upside down. Thanks to this, it sees almost everything that happens under
its body. Barracuda prawn observes bristle-legged shrimps carefully, choosing
its target. The wind is on its side, and soon the drifting raft of water hyacinth
appears right above the school of bristle-legged shrimps.
Having chosen its prey, the barracuda prawn swiftly attacks the school of bristle-legged
shrimps. Due to its camouflage longitudinal striped coloration, the predatory
shrimp remains invisible until it launches itself at the prey. There is no hope
for the bristle-legged shrimp, it is already too late. Having run into the school
of bristle-legged shrimps, the predatory crustacean drives them into a hysteric
flight. However, one individual has not managed to avoid a fatal encounter with
the predator. A large female, carrying a portion of eggs on its abdomen, was
not agile enough, and one claw of the barracuda prawn closed across its body.
The claw teeth pierce the shell of the prey; one of them penetrated deep into
its body, tearing the ventral nerve cord and paralyzing the prey. There was
a faint crunch, the legs of the caught shrimp trembling with violent convulsions.
The hunt is over.
Holding the prey in its claw, the barracuda prawn moves its abdominal legs and
swims back into its hiding place. Turning its back down, it clings to the roots
of the water hyacinth and climbs deeper into the thickets, so as not to attract
the attention of random fish that might try to take away its prey. Its maxillipedes
covered with hard jags literally saw through the shell of the prey with ease,
and the predatory shrimp quickly tears it into pieces and scrapes all the edible
particles out of the shell, rendering the prey a lifeless husk.
The predators that inhabit the shallow coastal waters of Lake Carpentaria belong
to many different groups of animals. Among them there are not only good swimmers,
but also creatures, for which the appearing in water is highly unlikely.
The thickets of floating plants are extremely dense in some places. Due to the
spongy, air-saturated tissue of the leaves or stems, these plants easily float
on the surface and do not sink, even when small birds perch on them to drink.
This particular aspect of these plants is used by one of the most unusual predators
that inhabits the shores of Lake Carpentaria.
... The sun has just begun its journey across the sky, and the air has warmed
only a little after the chill of night. Not even all the birds in the surrounding
forests have woken up, and nocturnal predators have only recently came into
daytime dream. This time is the most favorable for hunting for this unusual
inhabitant of the lake. A tiny fluffy ball of yellowish-white color runs along
the leaves of floating plants. This creature with long slender legs deftly jumps
over the leaves of the water lily, spread over the surface of the water. It
is so light that the leaf does not even bend when this animal runs over it.
This creature moves on four slender legs, keeping its balance with the help
of a hairless thin tail. It has an elongated head with movable ears and a flexible
proboscis-like nose. This creature is one of the many descendants of the marsupial
mice of the human era. A tiny creature, only a little bit larger than a bumble-bee,
is actually a ferocious predator, and sometimes the size of its possible prey
does not stop it.
The marsupial shrew runs along the leaves of aquatic plants, sniffing and looking
for signs of the presence of other inhabitants in the floating thickets. This
tiny marsupial is so light that even small leaves can support its weight. With
this key adaptation, the marsupial shrew easily examines almost all the thickets
of floating plants, except, perhaps, the continuous thickets of duckweed. The
flexible sensitive nose of the animal is constantly in motion: a warm-blooded
creature of this size literally burns up food in its stomach. A fast metabolism
requires a constant search for food, and the Marsupial Shrew can eat twice its
own weight in a single day. There is one essential circumstance that makes it
difficult for this particular individual to find food: it is an adult female
with cubs in her pouch. Therefore, she cannot dive, chasing fish fry and small
shrimp under the water, as males of this species do. Instead, she will plunge
her head into the water in search of prey.
Small snails creep on the underside of a water lily leaf, scraping microscopic
algae and small sedentary animals. They breed in large numbers and are often
eaten by other creatures. The marsupial shrew can hunt snails – it is an easy
and tasty catch. When the marsupial runs along the surface of the leaf, the
snails feel only slight vibration, which is not associated with danger in their
primitive behavior. The marsupial shrew runs along the edge of the leaf: sooner
or later one of these snails will appear here, and it will be easy to catch
it.
A large ramshorn snail crawls onto the surface of the water. It belongs to the
group of pulmonate mollusks, and from time to time must renew its air supply.
A thick conical tentacle carefully examines the surface of the water, before
the mollusk crawls out from under the leaf of the water lily and breathes, exposing
the edge of its shell from the water, where a hole opens, leading to its pulmonary
cavity.
When the sensitive nose of the marsupial shrew touches the snail’s body, the
snail jerks itself into its shell and firmly adheres to the lower surface of
the water lily. The marsupial shrew boldly thrusts her head into the water and
grabs the snail’s shell with her teeth. Backing up, she pulls the shell towards
her, bending the edge of the water lily leaf at the same time. With abrupt lateral
movements of the head, the marsupial shrew begins to tear the mollusk from the
leaf. The frenzied vigor of the tiny creature eventually meets with success,
and she rolls back to the middle of the leaf of the plant, holding a shell in
her teeth. In a final attempt to defend itself, the snail released a large amount
of sticky mucus from its shell. The marsupial shrew throws down the shell and
begins cleaning its face hastily with high-pitched sneezing. The animal then
grabs the edge of the shell with its teeth and begins to gnaw at it, breaking
off pieces. In a few minutes, the marsupial shrew reaches the snail’s body and
pulls it out of the shell with one sharp movement. She eats the prey even faster
and throws the emptied shell on the leaf.
Finding food can be dangerous for such a tiny creature. In the thickets of floating
plants, there are inhabitants that can tear off the head of this animal with
a single blow. In addition, they are in their native element under water, and
the marsupial shrew cannot hold its breath even for a minute. However, the marsupial
has speed on its side, which allows it to cope with the larger aquatic animals.
A small barracuda prawn hangs on the roots of a water hyacinth, waiting for
suitable prey to approach. But instead of this, the female of the marsupial
shrew approaches to its ambush above the water. The ramshorn snail was eaten
about a quarter of an hour ago, and now the animal is hungry again. The marsupial
shrew descends along the leaves of the plants to the water. Among the leaf stalks
swollen like bubbles, insect larvae can be found. This is not a bad meal either,
but it takes too much time to collect this food to be worth the effort.
The barracuda prawn, less than half of its adult size, is already well equipped
for hunting. The grip of its claws may not be as strong as that of the adults,
but they are just as deadly for prey of a suitable size. Despite her size, she
will be able to defend herself in case of attack. But everything will depend
on how the situation plays out, and one false move can ruin the entire hunt.
The marsupial shrew’s nose sinks into the water, and the creature’s nostrils
automatically close. However, sensitive vibrissae help the animal receive information
about what cannot be seen. The tip of the animal's nose slightly touches the
feathery antenna of the young barracuda prawn. This is followed by an instant
reaction – the marsupial shrew thrusts its head into the water, snatching the
abdomen of the prawn hidden in ambush with its teeth and pulls it out of the
water. The attack takes only a second: the hunting tactics of the marsupial
shrew relies on fast, devastating strike. The prawn, thrown out of the water
in the violent tussle, finds itself out of its native habitat, and its abdomen
beats the air idly, while the animal tumbles among leaves of water hyacinth.
The sharp teeth of the marsupial shrew grab the body of the prawn and the shell
is crunched in the shrew’s teeth. Having bitten the prey, which was twice as
long as itself, the marsupial shrew bounces back, avoiding the claws of the
predatory prawn. She must be careful: she has two rather developed cubs in her
brood pouch, and her maternal instinct keeps her from more decisive actions.
In addition, its prey is still full of strength and its claws are potentially
lethal. Within a minute, the marsupial shrew strikes the prawn repeatedly, attempting
to immobilize it. Finally, the movements of the prawn became weaker, and the
abdomen beats become less frequent. As life leaves the body of the prawn, the
marsupial shrew can start eating. She manages to provide herself with food for
the next few hours at little cost: the prawn had only scratched her nose, with
several drops of blood flow out of the wound.
After licking the wound and cleaning fur a little, the marsupial shrew proceeds
to eat its dinner. Sharp teeth bite into the meat of the prawn, and the animal
greedily eats the contents of its shell. This is food that is extremely necessary
for a creature with such a fast metabolism. The marsupial shrew feeds hastily,
trying to eat as much and as quickly as possible. At any time, competitors from
among her own species may appear, but it is much more likely that the remnants
of the prey can be simply taken by a larger lover of free meal. The marsupial
shrew cannot eat the whole shrimp alone even in half an hour – it needs to rest.
Her cubs need milk, and there will be more of it once the female can rest. Therefore,
she drags the remains of the prey into a large rosette of a water hyacinth and
settles down next to it. She feels weariness together with satiety. Having sniffed
air, the marsupial shrew made herself comfortable in the middle of the plant
rosette and had fallen asleep with one eye open.
Meat juice from the remains of the prey drips into the water. The smell of the
remains attracts fish, and they gather under the thickets of water hyacinth.
Trying to get to the remains of the prawn, they pull the roots of the plant
and squeeze between them to the surface of the water. The shocks of the fish
disturb the sleeping marsupial shrew female, and she interrupts her sleep several
times, looking around and sniffing. But she does not notice anything disturbing,
and again falls asleep.
Not only water, but also the wind carries the smell of the prey of the marsupial
shrew. To some of the inhabitants of the lake, one half-eaten prawn is not worth
the attention, but someone else can try to obtain even such a small prey. Another
marsupial shrew may try to take the carcass from the lawful owner. And this
creature soon appears on the islet of water hyacinth, attracted by the smell
of someone else’s bounty.
The intruder is a male. It is smaller and more aggressive than the female. Jumping
over the leaves of water lilies, he easily reaches the thickets of water hyacinth,
in which the female marsupial shrew hid her prey. Having jumped on the leaf,
the male stretches his sensitive proboscis-like nose and catches the appetizing
smell of prawn meat. Using his sense of smell, he quickly reaches a rosette
of water hyacinth with the half-eaten prawn in it. However, the male either
does not notice or pay attention to the smell of the female – who is resting
after her hunt. Obviously, this male is used to solving the problems of dominance
with force, so it can afford not pay attention to them.
This time, however, the male marsupial shrew makes a fatal mistake by underestimating
his opponent. Before he can take a piece of the prey he pretended to, the female
attacks, pouncing on the male. While she may not be as agile as the male, but
she is well rested and full of energy. The female grabs his shoulder and begins
to toss the male around like a dog. He cries in pain and gives a jerk in attempt
to bite his enemy, who has appeared out of nowhere. But the only thing he manages
to do is scratch the female with his hind paw. The female does not let go of
his shoulder, moving her jaws, as if trying to chew off a piece. The two animals
grapple in a ball and roll among the leaves of the water hyacinth. Eventually,
both animals fall into the water. They do not drown, because the sarments of
water hyacinth stretch and intertwine almost under the very surface of the water.
But the female is more concerned with the fate of her joeys – she cannot afford
to allow the water to get into the brood pouch. She feels the cubs stir from
the water seeping into the pouch, unclenches her jaws and jumps out onto the
leaf of the plant. The male does not realize that he was released, and for another
second, he still flounders in the water. Jumping out onto the floats of the
water hyacinth, he charges the female. His teeth only grab a flap of skin on
the female’s thigh, leaving a shallow but long cut. In response, the female
turns around and seizes him by the base of the tail. Squeaking in pain, the
male escapes from her teeth and flees. The free treat was too expensive for
him. The owner of the prey made some jumps following him, but didn’t begin to
chase him for real. She displayed him her force, drove the stranger away from
the prey and the only thing, she needs to do now is to finish her food. The
sharp teeth of the marsupial shrew will easily bite through even the strong
chitinous armor on the claws of the caught prawn, and after feeding, the remains
of the prey are unlikely to interest anyone larger than microscopic crustaceans
or worms.
In the ecosystem, every predator can easily become a prey, and this circumstance
even saves partly the herbivorous inhabitants of Lake Carpentaria from destruction,
maintaining a certain balance between predators and prey.
The shores of the lake are cut by shallow bays with swampy shores. This is a
great place for shrimp and fish juveniles to live – large underwater predators
rarely appear here. In addition, microscopic algae thrive in well-lit water,
serving as food for shrimp and fish fry. Near the coast, the surface of such
bays is usually covered with a dense carpet of duckweed, and this provides additional
protection and food for small animals.
A school of young bristle-legged shrimp feeds in shallow water. They are smaller
and more transparent than adults, so a predator hunting with the help of sight
would hardly detect them. But among the inhabitants of the lake there are those
who hunt in a different way, and they do not care what their food looks like.
A young barracuda prawn, barely a tenth of the size of an adult, is already
an active predator. Hanging on the carpet of duckweed from below, it senses
the presence of young bristle-legged shrimps. Its antennae, equipped with sensitive
bristles, make it possible to detect the movement of the surrounding water,
and the primitive brain of this predator distinguishes among the multitude of
sensations those that indicate the presence of prey. It seems that the prey
does not notice the hidden hunter: the prawn feels the movement of water next
to it. It targets prey almost blindly, but there is still a chance of success.
A long beak, widened at the end, plunges into the water quickly, almost without
a splash. With a lateral movement, it rakes a layer of duckweed from the surface
of the water and rises up. This is followed by another movement of the beak
along the surface of the water – now in the opposite direction. A school of
bristle-legged shrimp breaks loose and throws itself all over the place. Part
of the shrimp rushes into the silt and freezes, being lightly powdered with
it. Other individuals hide in the thickets. The short-sighted shrimps hardly
notice how long bird legs with thin toes passed by, but they feel the movement
of the water. The young barracuda prawn, alas, did not have time to react to
the danger that appeared so suddenly, and together with many other inhabitants
of the duckweed thickets, was swallowed by the owner of the beak – a long-legged
white bird with several black spots on its plumage.
This inhabitant of Lake Carpentaria is a scoopbeak, a strange bird, similar
to a heron or spoonbill, but is in fact a close relative of geese. Scoopbeak
has lost an ability to swim – its toes are not connected by a palama. But its
legs have become similar to those of a heron and allow their owner to wander
through the silt with ease. These birds are common in the tropics of the Old
World and Meganesia and inhabits warm shallow bodies of water. In places with
a seasonal climate, where bodies of water dry up for part of the year, the scoopbeaks
are migratory birds. And where the climate remains humid all year round, scoopbeaks
form large settled populations.
Scoopbeaks live and feed in flocks. They “mow” duckweed, often synchronizing
their movements. This food is rich in protein and vitamins, and these birds
do very well on such a diet. In addition, duckweed reproduces very quickly,
and they are always provided with food. Scoopbeaks are distinguished by their
aggressiveness towards ducks – their main competitors for food; they drive them
out to deeper parts of lakes and rivers, where they cannot feed themselves.
The scoopbeak’s beak is a device for filtering small food particles from water.
A feeding bird tilts its head to one side and makes an arc along the surface
of the water with its beak, moving its head and neck from side to side. Bristles
grow along the edges of the beak, forming a filtration apparatus. With their
help, the bird captures duckweed and other small floating plants from the surface
of the water. In addition to duckweed, scoopbeaks feed on a variety of floating
plant inhabitants, including mosquito larvae, as well as cladocerans and other
aquatic animals that accumulate in the upper layer of water. During the mass
flight of mayflies, when thousands of these insects die on the surface of the
water, scoopbeaks flock to the reservoirs, where this occurs, and feed in numerous
flocks. Apart from the aggressiveness towards water birds, scoopbeaks are among
the most peaceful lake inhabitants.
A scoopbeak flock wanders through shallow water. Duckweed thickets do not form
a continuous carpet, and birds feed only when they are in close proximity to
the plants. A small heron walks behind them, looking for invertebrates and fish
fry, which have been frightened by the scoopbeaks. It is not afraid to come
close to them, and sometimes snatches fish right from under their feet. Sometimes
one scoopbeak or another “mows” the water – the bird found a school of shrimps
or small fry near the surface of the water and catches them this way. During
feeding, the scoopbeaks are careful – they can be attacked by aella
eagles living in the forests around the lake. Therefore, the birds, taking
duckweed from the surface of the water, look at the sky with one eye, trying
to notice in time a black-and-white wide-winged bird, whose claws bring death
to them. But the danger can appear also from the other side – from under the
water.
A young eingana, born a week ago, has time to shed. At birth, it was already
a two-meter creature, completely ready to withstand possible enemies. For a
while, the newborn eingana lived off the supply of nutrients received in the
mother’s womb. Now, after shedding, it is ready for the first independent lunch
of its life. Reptiles almost do not need to learn – all the necessary behaviors
are innate, and they just need to apply them correctly. The most important thing
for a hunter is to choose the right prey. There are many animals around, and
the snake can smell them in the water. In the distance, a herd of bovipotamuses,
massive and stupid creatures, bask in the water. But for a young snake, even
newborn bovipotamus calves are too large, and adults can easily squash it into
jelly. The marsupial shrew, running along the leaves near the shore is too small
a prey item for a reptile of this size. Fish swim faster than einganas, and
they simply cannot be obtained. But a flock of scoopbeaks that have taken a
liking to the coastal shallow water is an ideal opportunity to get a good lunch.
These birds are just the right size and do not seem to be alarmed yet.
The eingana inhales a gulp of air and disappears under the water. It is not
visible under the leaves of water lilies and aponogetons floating on the surface,
and it is getting closer and closer to the bird flock. Scoopbeaks are busy feeding
– they gather duckweed from the surface of the water. The glare of sunlight
on the waves prevents the birds from seeing what the depth is hiding. And while
they are calm, but it will not continue as such for long.
The young eingana slides along the bottom, trying not to approach the surface
of the water. It keeps close to the thickets of the aquatic plants, and, in
order to replenish its air supply, raises its head among their leaves creeping
near the surface of the water. It manages to imperceptibly approach the feeding
scoopbeaks at a sufficiently close distance, and the reptile only waits for
a convenient moment to attack.
Scoopbeaks gather duckweed from the surface of the water, unaware that they
are moving towards danger. A flock of about two dozen birds stretches out in
a long line, gathering food from the surface of the pool. Raising their legs
sedately, the birds walk closer and closer to the hidden eingana. The reptile
senses the steps of birds, muffled by a layer of silt, and prepares to attack.
It tensed its whole body, ready to put all its strength into one precise throw.
And the birds are coming closer and closer to the snake...
Eingana’s throw was surprisingly accurate for its first hunt in its life. The
reptile grabs the scoopbeak’s neck, pulls the bird into the water, wrapping
its body around the bird. The caught scoopbeak had time to emit a short, alarming
cry and flapped its wings in an unsuccessful attempt to escape from the death
rings of the eingana. The rest of the birds, seeing what had happened, run to
the sides, flapping their wings, and take off, sending alarming calls to each
other. The panic of scoopbeaks spreads to the other inhabitants of the lake.
Small birds that arrived at the watering place took off and headed towards the
forest. A small kangaroo, lazily chewing on the leaves of marsh plants, jumps
out of the water in one jump and hops away from the shore. A herd of bovipotamuses,
resting nearby, reacted to the noise of the fleeing scoopbeaks with a lingering
bellow. The pool turned to a place of the tragedy became deserted very fast.
Eingana continues to tighten the rings around the scoopbeack’s body. It feels
the movements of the prey and whenever the bird tries to move, squeezes the
rings even tighter. The reptile is much heavier than the bird, and the body
of the caught scoopbeak gradually disappears under the water. Clouds of silt
rise from the bottom, a torn stem of a water plant, a white feather on the surface
of the water and several air bubbles escaped from the lungs of a strangled bird
– these are all evidences of the successful hunt of the eingana.
After a few minutes, eingana loosened its rings and the body of the scoopbeak
flutters in the water – the bird is dead. The snake is now ready to swallow
its food. Holding the prey with the coils of its body, eingana sticks its head
out of the water and takes a good breath of fresh air. Then it dives and begins
to swallow the dead bird. Having clasped the body of the scoopbeak with its
jaws, the snake begins to stretch itself onto its prey. Due to the elastic ligaments,
the jaws of the reptile open very wide. And the buoyancy of the water helps
the eingana swallow the bird quickly, without friction on the ground. Despite
the fact that it was the first lunch in its life, eingana finishes it in fifteen
minutes. After the prey takes its proper place in the stomach, the reptile gradually
falls into a passive condition. Now the only things it needs are warmth and
peace. The water in the gulf warms up well, and it makes no sense for the eingana
to swim away somewhere. It simply finds a place in the shallows away from the
coast and lays down at the bottom, exposing only the tip of its nose out of
the water for breathing.
Eingana is not the only reptile kind in the lake. Lake Carpentaria became home
to another kind of reptile, a representative of the archosaur clade that is
dying out in the Neocene.
On the sandy shores of Lake Carpentaria, long-tailed creatures covered with
armored hide bask in the sun. Their backs are covered with strong corneous scutes,
and their tails are laterally compressed and deep. When one of the reptiles
raises its head, one more feature of this species becomes noticeable – an elongated
narrow snout. The upper jaw in adults is flattened, and the teeth are directed
not from top to bottom, but to the sides. Because of this, the jaw of the animal
is a bit like the rostrum of a sawfish. This is a saw-nosed crocodile, one of
the specialized species of the crocodile order.
For 25 million before that time, people actively exterminated crocodiles for
various reasons, and in most of the former range, they disappeared. In the early
Neocene, other reptiles took advantage of the situation, becoming ecological
analogs of crocodiles in most of the former range of these animals. To survive,
the few remaining crocodile species specialized to avoid competition with their
replacements. In particular, saw-nosed crocodiles have become almost exclusively
fish-eating reptiles. In connection with the change in the diet, the behavior
of these animals has changed: they are less bloodthirsty than their ancestors,
who could, at an opportunity, eat their own smaller relative of smaller size.
In contrast to them, saw-nosed crocodiles actually do not pay attention to the
young of their own species, and young individuals roam freely among adult relatives.
Sometimes these crocodiles, basking in the sun, lie on top of each other, and
their resting places look more like a seal rookery.
A large saw-nosed crocodile rises to its feet and slowly walks towards the water,
dragging its long tail along the ground. On land, it seems awkward because of
the elongated hind legs, which is why its sacrum rises noticeably above the
shoulders. But, when the saw-nosed crocodile enters the water, it transforms.
Having pressed its front paws to the sides, it walks for some time in shallow
water only on its hind legs, and then sharply flaps its tail and moves into
the depths.
Saw-nosed crocodiles hunt only live prey and do not feed on carrion. They prefer
to ambush from the bottom, holding their breath for half an hour or more. All
this time the crocodile remains motionless, and the fish often lose caution,
swimming almost point-blank to the waiting predator. Usually, the saw-nosed
crocodile hides at the bottom near thickets of aquatic plants or among the snags,
where fish like to hide.
Near the coast, at a depth of about a meter, leaves of aponogetons sway. Superb
plants with thin decumbent rhizomes spread huge leaves, stretching in rosettes
over the surface of the water. The surface of the leaves is covered with an
elegant network of veins, between which the leaf tissues near the central vein
are slightly corrugated. The sun gives young leaves a beautiful reddish hue,
which changes to a deep green color as it grows. A little deeper from the surface
of the water, dense thickets of hornwort and pondweed rise. These long-stemmed
plants with small leaves provide shelter for numerous fish.
Among the leaves and stems, fish with deep bodies flicker. Their scales have
a green metallic sheen, and bright red spots reflect from the operculums. These
are disc rainbow fishes, representatives of a group of freshwater fish characteristic
of Meganesia. Once upon a time in the human epoch, their ancestors displayed
tremendous diversity, and among them there were many endemic species. But after
the introduction of new species of fish into Australia and New Guinea, the numbers
and diversity of native species began to decline. Rainbow fishes, capable of
living not only in fresh, but also in brackish water, survived in estuaries
and freshwater bays, as well as in isolated lakes. Some species of these fish
proved to be competitive in the new conditions, and their descendants took a
noteworthy place in the newly emerging ecosystems. The brackish waters of Lake
Carpentaria are home to many species of rainbow fishes. Sympatric speciation
led to the appearance of distinct differences in color in the different species
of these fish, which made it possible to distinguish quickly congeners from
representatives of other species. Some species of rainbow fishes in Lake Carpentaria
are remarkable with their bright coloration, including contrasting spots and
stripes, as well as “neon” spots that glow brightly in the rays of sun.
Ruby-red spot on the operculum of disc rainbow fish serves as a species-specific
identification signal. These fishes keep in schools in the thickets of underwater
grasses, and bright color spots help them find each other in the tangle of stems
and leaves. These fish rarely appear in open areas of shallow water, but when
they do, their school is a stunning sight to behold.
A flock of scoopbeaks flies over the lake, hurrying into shallow waters, where
the surface of the water is covered with duckweed. A flock of birds flies low
above the surface of the water, and shadows of flying scoopbeaks frightening
the inhabitants of the thickets, including the disc rainbow fishes, which hide
among the undergrowth. Flying over the water, scoopbeaks notice a saw-nosed
crocodile swimming to the fishing and choosing a position for ambush. This reptile
does not hunt scoopbeaks, so the birds avoid the saw-nosed crocodile only because
of its size. The flock of birds flies on, and the saw-nosed crocodile continues
its way, not paying attention to them. It is useless to hunt in the thickets:
the fish frightened by the crocodile only hide deeper into the midst of the
stalks. Therefore, the crocodile swims along the coast, looking for a more convenient
place to feed. Having covered about two hundred meters, it seems to have found
a good place for an ambush.
Here the plants no longer form continuous thickets in the shallow coastal waters.
From time to time, a local herd of bovipotamuses appears at this part of the
coast, bringing the confusion and ruin to the leisurely course of life in the
thickets. These gluttonous animals pull out whole armfuls of aquatic plants
and eat them, leaving cakes of manure in the water. After their grazing, continuous
thickets of underwater plants disappear. In the aftermath, only single bushes
remain, which for some reason were not eaten by these animals. But then the
real flourishing of life begins: the surviving rhizomes and tubers quickly form
new leaves, and the surviving shoots of long-stemmed grasses take root and grow.
Bovipotamus herds plow the coastal sand with their hooves, and the waves carry
away the silt that has accumulated among the thickets. Feeding of these herbivores
literally rejuvenates the natural community of coastal thickets, minimizing
decomposition and leaving areas free of vegetation, which prevents the appearing
of stagnant water zones in which silt begins to accumulate. In addition, many
species of aquatic animals prefer to live not in solid thickets, but on the
border of the thickets and areas of the bottom, free from plants.
The saw-nosed crocodile has found such a place. Here the waves throw onto the
shore a tree trunk, which was once carried by the river into the lake. The trunk
lies on a sandy bottom with its roots turned to the shore, surrounded by thickets
of pondweed, and on one side a vast sandy area adjoins it. Only in some places
it is overgrown with small bushes of pondweed – these are the remnants of thickets
eaten by bovipotamuses about two weeks ago. Inhaling a portion of air, the saw-nosed
crocodile sinks to the bottom and waits.
A school of disc rainbow fishes has been living in pondweed thickets in this
area for several months. Previously, the thickets were much more extensive and
there was enough food for all the fish. But then the situation changed: a herd
of bovipotamuses came here to feed, and the usual state of affairs was disrupted.
Large animals roamed along the bottom, raising clouds of silt, and devoured
the plants, tearing them up by the roots. The disk rainbow fishes that lived
on the edge of the thickets were forced to move to other places when the hulking
bovipotamuses destroyed their home. Gradually, the thickets of pondweed were
reduced to a small area around the tree trunk, where it was not so convenient
for bovipotamuses to feed. This area has accumulated a lot of fish that previously
lived in an area ten times larger. The disk rainbow fishes, finding themselves
in this captivity, immediately gathered in one common school.
These fish do not do well in these thickets. Once in there, they first eat everything
that can be eaten – worms, shrimp and snails. Some fishes pick the tops of the
pondweed shoots, but they were not to their taste. Of course, under such circumstances,
food ran out very quickly and hunger sets in. Some of the fish of other species,
forced to move here, left the thickets for several nights, crossing a vast area
of the sandy bottom, which had recently been densely overgrown with plants.
But disk rainbow fishes were not among them – they are too fearful and stressed
when they find themselves outside the thickets.
When the saw-nosed crocodile sinks to the bottom, several disc rainbow fishes
notice its movements and rush into the thickets. But then the reptile freezes,
slightly opening its mouth, and the fish returned to their usual life, completely
forgetting about its existence. The body of the hidden saw-nosed crocodile is
motionless, and only the eyes discreetly turn, following the fish. Several times
fishes swim out of the thickets one by one, but immediately hid, not giving
the saw-nosed crocodile a chance to catch them.
A school of disc rainbow fishes, crowding together in a small area of thickets,
attracts the attention of another predator. This creature is much smaller than
a crocodile, but it is also a skilled fish hunter. Its territory also turns
out to be a feeding place for bovipotamuses, and the animals destroyed a significant
part of the vegetation, forcing the owner of this territory to huddle on a tiny
patch of surviving vegetation that barely hides its body. This is a distant
relative of disc rainbow fish, the wide-mouthed rainbow pike. The length of
this fish is about 70 centimeters, it is an adult female.
After a significant part of the hiding places on the territory of the rainbow
pike was destroyed by bovipotamuses, it became much harder for the fish to hunt:
too few fish swim over the sandbank, and they do not always swim in range for
a sure strike. Therefore, the predatory fish decides to take a bold step – to
cross the area of the bottom with destroyed vegetation, and to hunt in the preserved
thickets.
After making sure that there are no large predators around, the fish leaves
its shelter. Wide-mouthed rainbow pike has the ability to change its coloration,
adjusting it to the shades of the surrounding area. At the beginning of this
risky journey, the color of the rainbow pike still retained its greenish tints,
that help it to hide among the plants, but within a few minutes its coloration
changed to sandy-yellow, corresponding to the background of the bottom. The
body of the predatory fish is covered with a marble pattern, which is remarkably
similar to the glare of sunlight falling to the bottom through the surface of
the water. Now the rainbow pike is ready to resettle.
In an open place, the fish behaves very carefully: the rainbow pike moves with
quick bursts from one shelter to another. It freezes near some driftwood, now
among the remains of plants, gnawed by the lumbering bovipotamuses, in a depression
at the bottom. The fish gradually approaches the trunk of a tree lying at the
bottom, near which its prey, disk rainbow fishes, hide in the thickets. Several
times the rainbow pike was frightened by the shadows of birds flying over the
water, and it laid down on the bottom and pressed its fins against the body,
trying to become invisible. But these were false alarms, and the fish reacted
to them only because it lacks any good shelter. And it noticed once a saw-nosed
crocodile swimming in the distance. This situation is extremely dangerous for
the fish: the sharp teeth of this crocodile, which form a kind of double-sided
saw in the upper jaw, can inflict terrible wounds on large fish, and small prey
will simply be chopped in half. But the crocodile has swam away, and, it seems,
does not notice the rainbow pike hiding at the bottom.
The goal of this risky march is getting closer. The broad-mouthed rainbow pike
smells the fish hiding in the thickets and becomes more and more daring. Finally,
it reaches the end of the trunk with broken branches sticking out above the
bottom. This is much better – the predatory fish lays down on the bottom next
to the tree trunk and immediately gains confidence in its movement and relieves
the stress of being in the open..
The rainbow pike cautiously swims along the trunk. It smells the fish hiding
among the plants and prepares to attack. Disc rainbow fishes flicker among the
plants, and all the attention of the predator is concentrated on them. The rainbow
pike is so busy hunting that it does not pay attention to something long lying
on the sand next to the plants on the other side of the thicket. It swims forward
a little more, and this object disappears from its field of vision, obscured
by leaves and shoots. The coloration of the predatory fish again changed from
sandy-yellow to greenish with vertical stripes of irregular shape, and it feels
like itself in its usual habitat. Deep and rounded bodies of disc rainbow fishes
flicker awfully close – the hunt looks to be successful.
The flock of disc rainbow fishes, suffering from starvation, hides in the thickets.
Of course, these fishes are able to survive hunger, and, if necessary, could
cross the dangerous area above the sandy bottom devoid of vegetation. But it
is not safe to do so during the day: there are many predators around. And the
biggest surprise for these fish is the appearance of a predator in their own
shelter.
The rainbow pike attacks disc rainbow fishes in one strike. Its wide mouth opened,
and one small fish is literally sucked in by the stream of water. In the next
instant, the teeth of the predator sink into its body. School of disc rainbow
fishes, smelling blood, is horrified. Fishes scurry about through the thickets
and some of them begin to appear at the edge of the thickets, sparkling in the
sun rays with bright spots on their gill covers.
Swallowing a shrimp or a long-bodied fish is easy – the rainbow pike has done
this more than once. But the deep body of the disc rainbow fish makes certain
difficulties for the predator, which is accustomed to swallowing prey whole.
Therefore, the rainbow pike has to work hard to do this. It shakes its head
and makes extra effort to swallow its prey. Thanks to elastic ligaments, its
jaw bones part and let the prey down the throat. One more gulp follows, and
the prey slips into the stomach.
A flock of frightened disk rainbow fish burst from the thicket, their colored
markings flashing in the sun. The bright brilliance brings the saw-nosed crocodile,
waiting in ambush, out of its stupor. The reptile reacts instantly: the saw-nosed
crocodile tosses up its head and makes a sharp lateral movement with it. At
the same time, its jaws are slightly open, and the terrible smashing teeth of
the upper jaw are fully operational. The head of the saw-nosed crocodile crashes
right into the school of rainbow fishes, and its teeth almost immediately find
their target. Two fishes impaled on the teeth of the upper jaw at once. Jerking
its head in the other direction, the saw-nosed crocodile drops them from its
teeth and manages to hit one more fish. The fish managed to escape from croc’s
teeth, but even so the fish’s life is rapidly coming to an end: the rainbow
fish is wounded and helplessly twitching near the bottom, falling to one side
and trying in vain to escape from the predator. It is bleeding, and even if
it manages to get away from the crocodile, it is unlikely to live until the
morning.
The school of disc rainbow fishes swims away, and the saw-nosed crocodile begins
to pick up its prey. Tilting its head to one side, it picks up the killed fish
with the teeth of the lower jaw and accurately moves the prey down the throat.
The wounded fish try to escape when the crocodile turns head to it, but long
jaws grab it, and croc’s teeth pierce its body. The hunt is over, and the crocodile
can now emerge to the surface for air, before returning to shore to digest its
lunch, basking in the sun.
Once in the open, disc rainbow fishes rush in search of shelter, sparkling with
red spots on their gill covers. The nearest thickets are quite far away, and
their color and spots attract the attention of one more saw-nosed crocodile.
This crocodile has just gone fishing and was not ready to see a large school
of frightened fish. But the reptile makes a decision quickly and rushes in pursuit
with haste.
Having pressed its front paws to the body, the saw-nosed crocodile waves from
side to side with its deep tail compressed from the sides, helping itself with
wide hind feet and membranes between the toes. Gradually, the distance between
it and the school of disc rainbow fishes is reduced, and in less than a minute
of chase, the crocodile has already caught up with the last fishes in the school.
Trying to injure them with the teeth of the upper jaw, directed to the sides,
the saw-nosed crocodile begins to shake its head. Fishes, however, manage to
avoid its attacks – in the water they move more freely than the crocodile. But
the crocodile is more adapted for fast swimming than these inhabitants of the
thickets, so the disc rainbow fishes are in real danger. But quite unexpectedly,
the saw-nosed crocodile turns around and swims to the shore as fast as it can.
The school of disc rainbow fishes dives deeper. When it becomes calmer, fishes
will be able to find thickets of underwater grasses suitable for life. In the
meantime, something else scares them. They feel the waves generated by the movement
of a huge wriggling body and rush to the bottom. And after a few seconds the
school of fish is covered with an ominous writhing shadow of an adult eingana.
Wriggling gracefully, the monster swims at a shallow depth. From time to time,
the huge snake sticks out its tongue, determining the presence of possible prey
by smell. The saw-nosed crocodile noticed the snake at the right time, but could
not hide its own presence – some of its droppings got into the water. And the
specific smell, well known to eingana, became a reliable guide for the predator.
An adult eingana can easily swallow a saw-nosed crocodile whole, and these reptiles
often become prey for the giant snakes.
The snake has poor vision, but the silhouette of the saw-nosed crocodile, desperately
rushing to the shore, is very noticeable on the surface of the water when viewed
from below. The crocodile paddles with a deep tail and helps itself with its
hind legs. In contrast, the snake’s movements appear to be slow and fluid, but
it is a deceptive impression. Snake swims very quickly and the distance between
them gradually decreases. At some point in time, the eingana’s muzzle appeared
at the distance of less than two meters from the tail of the saw-nosed crocodile.
The crocodile’s only salvation is to get to the shore: once on the shore, eingana
becomes slow and prefers not to hunt. Adult einganas oftentimes simply do not
leave the water once reaching a certain size.
The saw-nosed crocodile literally throws itself on the shore, selected by its
relatives, and clumsily runs away from the water at a gallop, raising its snout
up and looking behind itself with one eye. The rest of the crocodiles did not
see what caused this behavior, so only a few small crocodiles jumped up and
ran away, as if imitating this one. The frightened saw-nosed crocodile gallops,
making long clumsy jumps on its hind legs and plopping down heavily on the weaker
front legs. It runs away but does not take its eyes off the water.
Several ducks, swimming near the crocodile rookery, fly into the air with loud
shrieking. One of the adult saw-nosed crocodiles, basking on the shore, raised
its head and looked at them. But then a wave rushes to the shore, from which
a huge eingana’s head with an open mouth with pointed long teeth pulls ahead.
The giant snake is somewhat reminiscent of the killer whale of the human era,
which hunted seals in almost the same way, beaching themselves into their rookery
with the oncoming wave of the surf in order to grab the prey and leave together
with the wave receding from the coast. But there is no surf on Lake Carpentaria,
and eingana ran aground with most of its body. The front part of its body, however,
has the ability to move freely.
At the moment the eingana appeared on the shore, the saw-nosed crocodiles understand
what their relative was afraid of. They jump to their feet and run to the sides,
hoping to avoid the teeth and the deadly “embrace” of the eingana. The hunt
of the giant reptile clearly failed: the intended prey escaped, and now everyone
who can become the prey of this snake knows about its presence. But the reptile
is in no hurry to crawl away: keeping most of its body in the water, it crawls
along the beach from side to side, tasting the air with its tongue. It smells
the scent of saw-nosed crocodiles, mixing with the smells of forest animals
carried by the breeze from the forest. But they are all out of reach, and the
eingana returns to the hunt, sliding sideways into the water. But the giant
snake does not go far from the shore – its back can be seen in the shallow water
near the crocodile rookery.
Saw-nosed crocodiles follow the movements of the reptile. One of them, who almost
became the prey of this snake, is still breathing heavily, with its mouth open.
It can no longer stand the continuation of this chase – it needs some rest.
But eingana also cannot continue hunting – the physiology of the reptile imposes
restrictions on its capabilities. For some time, the giant snake crawls in the
shallow water along the coast. Then it pokes its head out of the water and breathes;
the hiss is clearly audible. Having renewed its air supply, the reptile sets
off in a majestic movement into the depths of the lake. Now it is not lucky,
but someday, when the underwater grasses will grow taller, it will return. And
then the careless crocodile will not notice the snake until it is too late...
Other individuals may be more successful hunters. A young individual of Eingana,
about eight meters long, chooses an area of the coast, overgrown with aquatic
plants, for an ambush. Here, in the shade of floating leaves of water lilies,
it is completely invisible to the animals that will come to the watering place.
And the snake will be able to choose a suitable prey for itself: it is already
large enough to cope with many of the inhabitants of the forests growing around
Lake Carpentaria. The snake cautiously pokes the tip of its muzzle out of the
water, prying the floating leaf of the water lily with it, and inhales a portion
of air. Now it can lie at the bottom for about a quarter of an hour, without
attracting attention to itself.
The eingana, hiding under water, does not see who exactly comes to the watering
place. But the reptile lies at the bottom of the lake and feels the shaking
of the ground under the feet of the animals walking along the shore. It may
not feel the light steps of rodents or small marsupials, but the steps of animals
weighing over fifty kilograms are felt by the snake very well, and the reptile
is waiting for a convenient moment to attack only.
These steps are very strange. The strength of the shaking of the ground indicates
that a large animal is walking. But it seems that it is in no hurry – the steps
follow one after the other at large intervals. From time to time, the resounding
shaking of the ground from heavy steps stops and is replaced by short rhythmic
sounds, as if this creature is scraping the ground with its paws. And the rhythm
of the shaking of the soil indicates that at this moment the animal is moving
not on four legs, but on two.
The steps are getting closer and more distinct. Eingana carefully breathes in
fresh air and continues to wait, hoping for success in the hunt.
In the Neocene, nature seemed to breathe deeply, freed from the heavy burden
in the form of the human race. After the end of the era of human domination,
the Earth’s biosphere as if healed its wounds and recovered from a serious illness.
The species of living organisms that managed to survive in the era of anthropogenic
pressure began to evolve rapidly, restoring biological balance and species diversity
in ecosystems. In such conditions, even decaying groups of living beings were
able to realize their evolutionary potential. And a representative of one such
group slowly wanders to the watering place.
If you look at the footprints of this animal, then at first glance it might
seem that it walked in the opposite direction. Its columnar hind legs are turned
with the feet to the side and back a little bit – it is a legacy inherited from
its ancestor. The front paws, armed with huge sharp claws, rest on the ground
with knuckles. But the main load of the weight of the huge body is taken by
the hind legs. The body of the animal looks like an artichoke, covered with
bristly hair and reddish corneous plates on the back. The narrow, elongated
head with tiny, half-blind eyes seems to be balanced by a rounded broadtail.
This creature, which looks like a hedgehog, anteater and a dinosaur at the same
time, is stegoechidna, the largest representative of the relic clade of primitive
egg-laying mammals on the Earth in Neocene epoch.
A slow metabolism does not contribute to the speed of movement. Stegoechidna
walks to the lake with its usual unhurried step, waddling awkwardly from side
to side. Even with all its effort, it cannot not run, but this does not cause
it any inconveniences – its food does not run.
A rotten tree trunk blocks the animal’s path. However, stegoechidna did not
bypass it. Instead, the beast sniffs the trunk, sniffing loudly, and sharply
hits it with the huge claws of its front paws. The rotting wood crumbles instantly,
and among the fragments of the trunk its inhabitants begin to stir. Several
large scorpions dart into the forest floor, but the sharp claw of the stegoechidna
plows up the ground, and a long tongue licks up one of them. Thick larvae of
capricorn beetles move helplessly among the dust, unsuccessfully trying to return
to the usual tightness of the galleries they had gnawed through. But most of
them only have a few minutes to live. The stegoechidna begins to rake the pieces
of wood, sniffing at them. Sensing the larva, it sticks out its tongue, covered
with sticky saliva, and licks it off. It swallows one by one all the large larvae;
only somewhere deep among the dust one more fat larva left and several smaller
larvae manage to avoid the sticky tongue of the animal. Finished with its food,
the stegoechidna slowly walks towards the water.
The eingana, who was lying in ambush, tenses. The footsteps are getting clearer
– someone walking along the shore is approaching the water. The reptile moves
cautiously and positions its head closer to the shore.
The stegoechidna comes to the water’s edge. For several minutes it looks around
and sniffs the air, trying to detect the presence of enemies in advance.
The eingana, hiding in the shadow of the water lily leaves, slowly creeps closer.
The stegoechidna sniffs the air in its nostrils and feels the aroma of flowers
of water lily growing not far from the shore. This beast is short-sighted and
cannot discern the flowers and leaves of the water lily. Therefore, stegoechidna
does not notice how one leaf has swung to the side away from the wind.
The eingana carefully takes up position before the decisive blow. The entire
body of the reptile is like a compressed spring. Snake is ready to attack.
Having made sure that it is safe, the stegoechidna lowers its head to the water
and begins lapping noisily.
The head of the huge snake literally flies out of the water with tremendous
force. The eingana strikes its head into the shoulder of the stegoechidna and
immediately, right in the rush, wraps the front of its body around the neck
and shoulders of the stegoechidna. In light of this sudden attack, the stegoechidna
sways, falling into the water. Without releasing its deadly embrace, eingana
begins to move out of the water, putting new loops on the body of the stegoechidna.
An animal like a kangaroo or a bovipotamus calf would hardly have been able
to resist such an attack for more than a few minutes. The loops of the muscular
body of the snake, squeezing the chest of the victim, deprive it of the opportunity
to breathe. But this time the snake met a worthy opponent.
Due to its slow metabolism, stegoechidna is able to hold its breath for a long
time, so it easily tolerates suffocation. Its body constitution is very dense,
and its bones are strong. In addition, stegoechidna has extraordinarily strong
muscles, so it even manages to inhale while being in the rings of the eingana’s
body. With an inhalation the hope of liberation comes, and the stegoechidna
begins to act. It squeezes strongly the body of the eingana with its front paws
and deeply plunges its claws into the side of the reptile.
Feeling pain, eingana begin wriggling, literally rolling through the shallow
water along with the stegoechidna, entwined with rings of snake’s body. It looks
like this prey is not going to give up too quickly. Usually, marsupials or placental
mammals die within a few minutes, having fallen into the “embrace” of the eingana,
and the snake manages to deal with them without getting injured. But it looks
like the reptile made a mistake this time. It attacked an animal that is not
only too large, but also one that can fight back. Now it needs to get away from
such a dangerous opponent, and it pulls the stegoechidna to the depths. The
reptile’s grip gradually weakens, but the stegoechidna continues to hold the
snake in its front paws. From time to time, the beast loosens its grip, but
it is done only to squeeze then even tighter and to plunge its claws into the
enemy once again. Several cut wounds inflicted by the long claws of the stegoechidna
are already bleeding on the body of the giant snake. Now it is a snake’s turn
to try to free itself from the beast holding. The loops of the reptile’s body
loosen and release the stegoechidna. With a few strong body movements, eingana
tries to escape from the claws of the stegoechidna. This animal thinks as slowly
and unhurriedly as it breathes. It hardly gets the idea that the reptile no
longer poses a danger to it. Finally, its mighty paws unclench and the eingana
rapidly sneaks away out of its claws. Leaving a bloody trail, the reptile hides
in a greenish murk.
Stegoechidna makes some efforts to stand on its feet. During the fight with
the snake, it appeared quite far from the shore, and now the water reaches its
shoulders. Raising its head, the stegoechidna takes a deep breath and trudges
along the bottom towards the shore. Its head is lowered into the water, and
the animal seems to be sniffing something under the water. But it is just an
illusion – it is just the normal position of the animal’s body. As it approaches
the shore, stegoechidna appears from the water more and more. However, shortly
before reaching the shore, the animal stops. The water lily, the leaves of which
helped eingana to hide, attracts the attention of the beast. With a few movements
of its claws, the stegoechidna cuts off the leaves of the plant and digs out
the tuber from the silt. With some effort, it went through the mouth of the
stegochidna, and the huge animal begins to chew the tuber, rubbing it with corneous
plates, which, in due course of evolution, appeared in the jaws of its immediate
ancestors, instead of the reduced teeth. Such a large animal cannot live by
feeding only on insects and other invertebrates. Perhaps it was the ability
to consume available plant food that allowed stegoechidna to become a giant
among monotremes.
Stegoechidna is one of the numerous guests of the lake. It does not live here
permanently, but only comes to drink or feed for some time on the gifts of the
lake – tubers of coastal plants or fish and shrimps captured in drying puddles
along the shores of the lake. But the life of other species of mammals is much
stronger associated with the lake. Bovipotamuses are the most numerous of the
large inhabitants of Lake Carpentaria. These descendants of the water buffalo
have perfectly adapted to the aquatic lifestyle and are, to some extent, analogous
to the hippos of the human era. Each herd of these animals occupies a certain
area of the coast, and the boundaries of the territory are marked with piles
of manure, which are regularly refreshed. Clumsy bovipotamuses most often go
out to graze at night, and at this time they can go far from the lake shore.
In the thicket of the rainforest, the darkness seems even more impenetrable
due to the fact that the dense crowns of trees obscure the faint light of the
moon and stars. Owls echo in the crowns of trees with hollow voices, and the
background noise is created by numerous frogs and insects. Crickets chirp in
every manner, and the voices of cicadas resemble whistles, metallic ringing
or grinding. And frogs, claiming their rights to the territory, not only croak,
but also bark like a small dog, or squeak abruptly. Bovipotamuses do not pay
attention to these sounds, but if the night singers suddenly become quiet, these
giants raise their heads and begin to sniff the air and listen, hoping to recognize
in time the quiet rustling footsteps of a creeping predator among the sounds
of the forest. If the alarm turns out to be false, insects and frogs continue
their nightly concert, and bovipotamuses continue the interrupted grazing. In
places, where these animals grazed at night, the growth of trees in the undergrowth
is completely destroyed or gnawed.
The heavy smell of bovipotamus herd attracts thousands of blood-sucking insects
– mosquitoes and midges. On the neck, back and sides, bovipotamus is protected
by a thick skin, which is hardly bitten through by both a predator and a scavenger.
But on the head and groin, the skin is much thinner, and these places are more
intensely attacked by blood-sucking insects. Trying to escape from them, bovipotamuses
wallow in the mud, but it does not help much – after a short time, the winged
bloodsuckers return. But insects, in turn, attract bats, and these winged creatures
save bovipotamuses from suffering, exterminating a significant number of blood-sucking
dipterans.
When dawn begins, bovipotamuses leave the place of night grazing and move to
their native habitat. These animals are quite conservative in their habits and
follow the same paths for many generations. In some places along the coast,
the rainforest is cut by wide “roads”, which have been trodden and extended
by several successive generations of bovipotamuses. In these places, the plank-buttress
roots of trees are broken by the hooves of bovipotamuses, the shoots are eaten
or trampled into the ground, and even the ground itself is tightly compacted.
The width of the trail is such that three adult bovipotamus pass freely along
it shoulder to shoulder. Herbaceous plants grow abundantly along the edges of
such a path – while bovipotamuses do not eat the greens during the movement,
their manure serves as additional fertilizer for the plants.
Bovipotamus herd moves along the trail. A large male walks at the forefront
– it is the leader of the herd. Behind him there are males of lower rank and
females with calves. Old animals close the herd procession – they barely have
enough strength to stay close to their relatives. The ground is rumbling with
the beats of wide hooves, and small animals that find themselves in the path
of the herd can be crushed into paste. Usually, a herd of bovipotamuses is accompanied
by birds, which expect a free treat in the form of animals trampled by the herd.
The sun barely has time to rise above the horizon when the first members of
the herd already enter the lake. Bovipotamuses will spend the next few hours
sleeping lightly and chewing their cud.
A herd of bovipotamuses rests in shallow water after overnight feeding. They
swim in the water, barely touching the bottom with their feet, ruminating and
blowing from their mouths bubbles of methane, formed during the fermentation
of plant matter in the stomach. Several animals that are not full during the
night feeding do not sleep. They eat reeds in the coastal thickets, pulling
it out in bunches from the silty soil. Birds feed next to the massive animals.
Herons walk on the backs of bovipotamuses and sometimes peck on fish that inadvertently
swim too close to the surface of the water. In shallow waters near the herd,
the scoopbeaks walk, making steps pompously. From time to time the birds lower
their heads into the water and with lateral movements “mow” the duckweed, simultaneously
straining fry and small crustaceans out of the water. Scaring aquatic animals,
bovipotamuses help the scoopbeaks and herons feed. In addition, it is safer
around them. Saw-nosed crocodile, swimming to hunt, prefers not to approach
bovipotamuses. There are females with calves in the herd, and they can easily
pounce on this crocodile if they think it poses a danger to their offspring.
When the sun rises high enough in the sky, the herd begins feeding in the water.
Bovipotamuses come to an area of their territory, where thickets of giant eel
grass sway at a depth of about two meters. Its leaves reach a length of four
meters and spread over the surface of the water in a continuous carpet. Breeding
with the help of runners, eel grass quickly conquers living space and forms
impenetrable thickets that are inhabited by fish, shrimps and other inhabitants
of the lake, which love solitude and shelter.
Bovipotamuses walk along the lake bottom, raising clouds of silt. They are approaching
the thickets of eel grass, and their presence will disrupt the usual life of
many lake inhabitants very soon.
Having reached the thickets, the animals begin to pick off long leaves waving
in the water. Calves stay on the surface of the water, eating only the tips
of the leaves, while the adult bovipotamuses dive and uproot plants to engulf
them slowly while floating on the surface of the water. Dozens of fish, disturbed
by the appearance of the bovipotamuses, leave their hiding places. Some of them
are in a hurry to hide in the still untouched thickets, while others, on the
contrary, swim near the bovipotamuses and catch shrimps and small fish that
have lost their shelters.
When bovipotamuses finish feeding, very few plants survive. But the survivors
will have room to grow, and in a few months the thickets will be as dense as
before. This is an absolutely natural course of events – the activity of bovipotamuses
rejuvenates the biocenosis, preventing productive underwater “forests” from
silting up and choking off young growth with dying leaves.
A herd of bovipotamuses grazes among aquatic plants, like ordinary cows in a
forest. Calves swim next to the adults – they are just learning to dive for
food. And the adult male, the head of the herd, is always on the alert: he must
ensure the safety of the herd and recognize the approach of an enemy in time.
And it is exceedingly difficult to do it, because sometimes the enemy appears
from under the water, where the senses of bovipotamuses cannot recognize it
in time.
An adult eingana is searching for food. The last time it ate was about a month
ago and it has been hungry for some time. Due to its slow metabolism, the reptile
may not go hunting very often, and the lake in general can supply with food
a viable population of these predators. The reptile swims at a depth of about
two meters. It is poorly visible from the surface; therefore waterfowl do not
even notice this predator and continue to feed quietly. The eingana does not
pay attention to them – a monster about eighteen meters long needs more substantial
prey than a duck. The reptile senses the presence of possible prey – the smell
of the bovipotamus’ manure and urine spreads far in the water, and the senses
of the eingana are able to recognize even the smallest amounts of odorous substances
dissolved in water.
The appearing of the giant snake comes as a surprise to bovipotamuses. When
the long body of the reptile emerges from the depths, the leader roars in fear
and the herd instantly panicked. Large males are not afraid of the eingana:
they beat the water with their hooves and blow bubbles, emitting a threatening
roar under the water. The snake does not hear their roar, but it senses waves
from the movements of hooves and gurgling with its whole body. Youngsters caught
off guard panic more than adults. The calves rush to the shore, and one of them
climbs onto the body of his mother from fear. Adult animals swim to the shore
and a stampede begins in the shallow water. One bovipotamus slips and falls,
and the rest of the animals run straight over its body, and the trampled beast
bellowing in pain. The herd’s momentary delay determined the success of the
attack. One young bull was left in the back rows, and the snake caught it with
one accurate rush.
Grabbing the prey by its hind leg, eingana clenches its jaws, and its pointed
teeth sink deep into the bovipotamus’ flesh. To deprive the prey the opportunity
to escape, eingana throws the bovipotamus down into the water and quickly wraps
it with several rings around its body. Bovipotamus tries to break free, moaning
pitifully in vain as it watches its relatives in such a rush to leave the water.
But no one will come to help him. The muscles of an adult eingana are too strong
to be unclenched, and the captured beast is doomed.
The eingana pulls its prey into the water, continuing to squeeze it with body
coils. It responds to every movement of the prey by tightening its coils even
tighter. After a few minutes, the reptile feels the final convulsive tremor
of its prey, after which the body of bovipotamus goes limp and then stays motionless.
Now eingana can relax its grip.
Einganas prefer not to hunt adult bovipotamus males. The horns of these animals
are directed to the back and sides, and the animals themselves reach a weight
of about 400 kilograms. It is quite difficult to swallow such a massive prey,
and it is completely impossible to regurgitate it also – tips of the horns,
directed backward, prevent the prey’s body from leaving the esophagus, and the
carcass of bovipotamus can get stuck in the throat of the snake, killing it
slowly. Therefore, young animals and females most often become prey of the giant
eingana.
Swallowing a bovipotamus carcass is a difficult task. However, Eingana does
this job perfectly. Feeling the prey with its tongue, the reptile finds its
head and latches onto it. Moving alternately the upper and lower jaw forward,
it begins literally to stretch its body onto the prey. The bull's head quickly
disappears into the snake’s throat. When the jaws of the snake reach the shoulders
of the prey, the elastic ligaments holding the jaw bones stretch, and the snake
continues swallowing its prey. In order not to hold its breath, the reptile
sticks the tip of the trachea out of its mouth, in the middle of the lower jaw.
It turns to its side, and the trachea is now above the water. The reptile breathes
freely again, continuing swallowing its prey.
In half an hour, only the hind legs and tail of the bovipotamus are sticking
out of its mouth. The jaw bones gradually fall into place, the ligaments between
them contract, and a huge swell forms right behind the head – it is the body
of the swallowed prey. With a few smooth movements of the front part of the
body, the eingana pushes the prey deeper along the esophagus, and soon it takes
its place in the stomach. Now the eingana regains the ability to swim freely.
It turns around and disappears in the depths of the lake.
Eingana does not swim too far from the coast – here it finds its habitual food
and places for the rest. Far from the shores of Lake Carpentaria, there are
completely different living creatures that rarely get in coastal waters. The
main food source here is phytoplankton, which cladocerans feed on. These creatures
are remarkable in their fast growth rate and rapid reproduction, which helps
them to resist successfully the feeding activity of predators. Birds flying
over the surface of the lake away from the shore can see that the water of the
lake has different colors in different places. These are signs of the presence
of zooplankton – crustaceans of various species. Most often, their swarms are
reddish or grayish in color. But sometimes the congestions of crustaceans seem
to be crossed by silvery strokes – it is the fish living in the water column
that feed.
A shoal of crustaceans, when viewed from under the water, resembles fog. Numerous
microscopic creatures move in the water column, continuously filtering unicellular
algae. They perceive only their microscopic neighbors of the same size – fish
fry, larvae of worms and mollusks. Large animals are something that is beyond
their perception.
A large school of fish swims at a depth of about two meters. They are grayish
in coloration with a metallic sheen and dark longitudinal stripes on their sides
– it is branchiochromis, one of the most abundant fish species in Lake Carpentaria.
Their appearance has an unusual feature – large head with a wide mouth. But
the teeth of these fish are very small and serve more to “lock” the mouth rather
than to hold the prey. After all, the food of these fish includes planktonic
crustaceans only.
A school of branchiochromises scatters in a range over ten meters wide. As long
as there are no predators nearby, it is safe. Branchiochromis fishes spend their
entire life away from the coast and prefer not to approach floating objects.
If they fall into coastal waters by mistake, they immediately try to go into
open water, away from the numerous predators of the coastal thickets.
The first fishes in the school feel the approach of the congestion of planktonic
crustaceans and begin to feed without slowing down. They simply open their mouths
and filter the water through thick gill rakers. From time to time, fishes close
their mouths and swallow the mass of crustaceans that have accumulated on their
gills. This feeding method is highly effective for pelagic fishes, since it
allows them to not slow down and does not make the fish more vulnerable to predators
at the time of feeding.
Having heard the characteristic sounds made by feeding relatives, fishes from
the back of the school, changed their position. They swim forward and to the
sides of the front of the pack, and after a few minutes the pack stretches out,
forming a broad front. Fishes line up in the way not to follow one another,
and swim with their mouths wide open.
The array of branchochromises crosses the congestion of crustaceans, leaving
behind patches of water where hardly more than half of the former number of
these creatures remains. But this is not a problem for rapidly breeding cladocerans
– due to their growth rate, abundance of food, and parthenogenetic reproduction,
they easily repair damage from predators. In addition, fish that feed on branchiochromis
turn out to be their allies to some extent.
A small school of fish, larger than branchiochromis, rushes at a depth of about
three meters. These slender and strong fish, each about 70 cm long, are somewhat
reminiscent of marine pelagic fish – horse mackerels, tunas and trevallies.
They are called carangochromises and are also descendants of tilapia and distant
relatives of the branchiochromis. In contrast to the planktivorous branchiochromis,
the large carangochromis is an active predator. Branchiochromis is one of the
basic kinds of prey of these giants. The wide mouth of carangochromis allows
it to swallow easily fish as long as a third of its own length.
Carangochromises seek prey by smell. When they hear the characteristic sounds
of a feeding school of branchiochromises, their excitement grows. The predators
begin to move their tails faster and accelerate, as if afraid to be late for
dinner. Their large eyes distinguish a cluster of branchiochromises feeding
near the surface of the water, and predators unmistakably go in their direction.
It is hardly possible to understand which one of branchiochromis school was
the first to notice the approach of predators. The frightened fish rushed to
the only shelter available in the open water of the lake – to its own relatives.
Its sudden movement was noticed by other branchochromises faster than the cause
of the panic. The regular array of feeding fish was broken and disintegrated,
like a drop of mercury, into several spherical schools. Several small flocks
immediately merged into a larger one.
Carangochromises swim alongside the packs of branchiochromises. They expected
on a surprise attack, allowing them to cut off several fish from the general
school and eat them. But their plans were disrupted. The surface of each spherical
school of branchiochromis literally boils from the bodies of fish trying to
hide from predators among their relatives. Two large schools of branchiochromises
are slowly moving towards each other, while carangochromises are circling at
a distance, and then merge into one common school. Now it is more difficult
for carangochromis to get food for themselves. However one of them has decided
to take a desperate step and rushes straight into the cluster of branchochromises.
School of frightened fish literally swallows the predator, and then releases
it from the other side – without prey. But for some fractions of a second, several
fish left the school, in order to rush then under the protection of their relatives.
And a minute later another carangochromis attacks the pack. It does not rush
into the middle of the accumulation of prey, but swims along a tangent. Branchiochromis,
frightened by such a maneuver, rushes to the sides, and one of the fish for
a second finds itself outside the school. Its fate was sealed: the mouth of
the carangochromis opens like a pipe and sucks the prey into its gullet in a
split second.
For several times carangochromises attacked branchiochromis school, and about
half of their attacks were successful. Having filled their stomachs, the predators
gather again in a pack and leave the battlefield. Branchochromises cannot calm
down for a long time after the predators have disappeared in the blue haze:
their school continues whirling in one place, retaining its spherical shape,
but gradually spreads out and fishes continue feeding again.
Carangochromises almost never appear near the coast. These fish prefer the clean
and oxygen-rich water of the central part of the lake, experiencing some stress
in the silt-polluted water of the coastal areas. After a successful hunt, the
predators swim guided by their sense of smell. In the central part of the lake,
where there are almost no visual reference points, their sense of smell helps
the animals feel at home. Carangochromises swim, feeling the scent trail left
after their congeners. Soon they catch up with a more numerous carangochromis
pack and unite with it.
Usually, carangochromises prefer the society of congeners, although they are
predators. But the amount of prey in the lake is enough for these fish to feed
together. But occasionally some fish have to leave the society of their relatives
in pursuit of more important goals.
A pack of carangochromises enters the area of reddish water. Their sense of
smell tells these fishes that they are surrounded by a huge congestion of crustaceans,
which give the water such a color. Visibility decreases sharply and fishes swim
slower. They notice several blurred silhouettes slowly swimming among the clouds
of microscopic crustaceans at a fairly large distance from each other. When
carangochromises swim closer, they distinguish their relatives in these silhouettes.
But loners clearly do not seek to join the pack and go to an area of clear water.
When several carangochromises of the pack swim up to one of these individuals,
that fish takes a warning pose, turning to its relatives sideways and sharply
waving its tail, sending a wave of water towards the strangers. By these actions,
the loner makes it clear to the fish from the school that it is better for them
to stay away from this one. Carangochromis pack continues its way and soon hides
in the distance.
The lone caragochromis is a male. He has a large head with a swollen throat,
and his body coloration is much paler than usual. Only the lips of this individual
have a bright white color. These features of the fish’s appearance are associated
with the important work that this male performs. When the carangochromis pack
left, the single male made sure that everything around was calm again. He did
not notice any single large living creature around – only myriads of crustaceans
living their hectic life. Then the male opened his mouth.
Fry swim out of his mouth in a living stream – about four hundred of them. They
look little like their father yet – they are translucent cross-striped creatures
about half a centimeter long. They came into being about two weeks ago and have
already grown a little, but so far, the male manages to contain his entire brood
in his mouth. The ancestors of carangochromis, tilapias, raised their offspring
in this way, but laid eggs in a hole at the bottom, and only then took them
into their mouths. In the course of evolution, some of the descendants of tilapia
adapted to the pelagic way of life, and the bottom stage of spawning in them
gradually disappeared. Only the “breaking away” from the bottom did the descendants
of tilapia real pelagic fish. Carangochromis belongs to just such species.
The white lips of the parenting male represent an important signal for his offspring:
a sign of safety and protection. Feeding in open water, the fry constantly keep
the lips of the male in the field of view, and in case of danger they return
to him. The male carangochromis carried the entire brood to the cluster of crustaceans
and releases, allowing the fry to feed. Already at the moment of hatching from
eggs, the fry of carangochromis are quite large, and only the large size of
the parent itself allows him to bear numerous offspring. The large size of the
fry gives them a certain advantage: having learned to swim, the fry immediately
begin feeding on young crustaceans, and later pass on to adults. Having got
out of their father’s mouth, the fry feed on their own. Already at this time,
predatory tendencies begin to appear. Lagging in growth fry become victims of
their larger siblings. The father does not intervene in the conflicts that occur
between the fry - he is too big for this. His parental responsibilities include
providing the offspring with food and protection from large enemies. Therefore,
incubating males of carangochromis go to where there is ample food for their
offspring.
When the fry were full, they began to return to their parent’s mouth. To get
into the father’s mouth, the fry simply nip his lips, and the male’s jaws open
just enough so that they can swim into his mouth. The male of carangochromis
rather senses the presence of his fry by the movement of water around them than
sees them. A caring dad does not count his fry and the loss of several individuals
from a brood of several hundred individuals only increases the chances of surviving
of the remained ones. However, the male carangochromis is a caring parent.
A whole swarm of fry hovers around the head of an adult male carangochromis,
which is motionlessly hanging in the water column at a depth of about a meter.
Their father chose a good place for the offspring outing – right in the middle
of the congestion of copepods. His fry feed – they need to do it as actively
as possible, since in the first weeks of life they grow intensively. The male
behaves calmly and confidently – he does everything according to his parental
instinct. This large carangochromis has raised offspring many times and the
parental instinct, supported by experience, did not let him down.
The male suddenly feels that the fry are frightened of something: their movements
become sharper and more fussy, and at once several fry began to nip the edges
of his lips. The male opens his mouth and moves his fins invitingly. The whole
brood rushes into his mouth, and five seconds after the assembly signal all
the fry were already safe in his throat pouch. The male wags his tail lazily
and turns around.
The troublemaker turned out to be a young male carangochromis, also engaged
in raising offspring. It is located about three meters from the adult male and
does not hurry to move away when the adult male pays attention to him. Obviously,
he was attracted by the mass of crustaceans and decided to pasture his brood
right here. But an adult male cannot allow a stranger to do this – now he perceives
the alien male and his offspring as a danger to his own brood.
The young male opens his mouth and releases his offspring to the “pasture”.
He does not pay attention to the large male that is nearby, and thus has made
a huge mistake. Usually, males with their offspring keep at a certain distance
from each other in order to avoid competition between fry from their broods.
But this male barely had time to hide his brood in his mouth when the large
adult male swam up to him, displaying his side and spread fins. He chooses to
confine himself to a demonstration of size and strength, since his mouth is
full of his own brood, and a fight means a great danger of losing part of the
offspring from an accidental snout hitting an opponent in the throat. The young
male tries to defend his right to a part of this territory: he also turns to
his opponent sideways and opens his fins, trembling with its whole body. But
the older adult male confident in his superiority, waves his tail, and the young
rival feels the force of the wave launched at him. He prefers to tighten his
fins and to retreat to a safe distance. The winner opens his mouth again, releasing
his brood for feeding.
Rearing offspring is an extremely dangerous stage in the life of a male carangochromis.
As long as he takes care of the offspring (about six weeks), he will have to
observe a strict fasting. At this time, the fat outgrowth on his forehead dissolves,
which is used for demonstration during courtship rituals. Actually, the female
estimates particularly the size of this outgrowth, when forming a pair with
the male: “brainy” males enjoy special preference, since this is a sign that
they ate well before pairing. A small outgrowth on the forehead means that the
male is less prepared for raising offspring: such individuals, as a rule, are
more worrisome during the period of bearing eggs and larvae, lose a lot of weight
or try to part with the growing fry as soon as possible. Usually, the brood
of such males quickly dies at various stages of development.
The incubating caragochromis is always on the alert. While the fry are small
in size, even branchochromises, which usually themselves become the food of
this species, are dangerous to them.
The male carangochromis monitors the world around him. He sees his fry, which
feed on crustaceans, swimming around his head. Somewhere far from himself, he
distinguishes the silhouettes of several relatives, the same large males. They
are also engaged in raising offspring, but they keep at a fairly large distance
from each other and from him. Therefore, the male carangochromis is calm. The
time of raising the offspring is quite different from its usual way of life,
when it is constantly busy looking for food and chasing prey. In the meantime,
he has other concerns.
Somewhere to the side, a young male carangochromis is swimming. This youngster
tried to feed his fry in this feeding area, but was expelled and is now looking
for a suitable place to feed his offspring. However, the better parts of feeding
area are occupied, and he will have to work hard to find a suitable place and
at the same time not cause aggression from any of its stronger relatives. Therefore,
he has to clench his jaws tighter and get out to the edge of the feeding area.
The young male of carangochromis swims cautiously – he has to stay away from
the stronger owners of the plots, into which the crustacean accumulation is
invisibly divided. Having caused the displeasure of several larger males, he
manages to get to the edge of the feeding area. Here the competition is much
less, but food for the fry is much scarcer – crustaceans form only separate
flocks almost under the very surface of the water. It is not very favorable
for feeding the fry – while they are small, near the surface of the water they
may simply get motion sickness. But their parent has no other choice, and the
male releases fry almost at the very surface of the lake, were small crustaceans
scurry about. The fry have become very hungry while their father was looking
for a place to feed them, so they literally pounce on the crustaceans and begin
to fill their tiny stomachs. They quickly eat everything that could be eaten,
but they are unlikely to be full. Therefore, the male simply gathers them all
in his mouth and swims to the next flock of crustaceans. Of course, this is
a more demanding tactic, but he will be able to feed his offspring at a time
when the fry should have food all the time. And there is another advantage in
its position on the border between the congestion of crustaceans and the area
of clear water.
In the distance, among the greenish haze, the silhouette of another inhabitant
of Lake Carpentaria appears. A wide flattened head, pointed fins, a large unequal-lobed
tail and a characteristic triangular dorsal fin – perhaps it would be more appropriate
for this creature to live in the sea. These animals represent a legacy of the
maritime past of Lake Carpentaria, striking fear in those who cannot resist
them. The creature approaches a flock of planktonic crustaceans in search of
food, but the crustaceans themselves are of less interest to him than anything
else. This is a shark – a representative of the genus to which in human epoch
the bull shark belonged, the ancestor of this species. And the descendant of
this predator retained the most characteristic features of its ancestor, including
bloodlust. This species has two main differences from its ancestor – size and
color. These sharks reach only one and a half meters in length, and more often
they are even smaller. And the color of their body is not dull gray or brownish,
but green, and even bluish green. This is a green shark, one more predatory
species in the lake.
A lake for aquatic animals is somewhat like an island for terrestrial animals.
There is a strictly limited food supply here, which can feed a smaller population
than the open water of the sea or the basin of a large river. And from here
it is difficult to settle anywhere else, except for directly accessible nearby
places. Therefore, large animal species, “locked” in a relatively small lake,
evolve like large land animals that appeared on a small island: in order to
maintain a sufficiently large population, they decrease in size. Nevertheless,
dwarf sharks are not inferior to their distant ancestors in terms of ferocity
and voracity, adjusted only for size.
After one green shark, two more appear from the mist of the lake. A young male
carangochromis notices them in time. He immediately gives a signal for danger,
and the fry disappear into his mouth in just three seconds. Having tightly compressed
his lips, the male freezes at the surface of the water, trying not to give himself
out with unnecessary movements. The three sharks, each almost three times his
length, swim under him at a depth of about five meters. He was not noticed,
and thus has saved his offspring.
The males who occupied the feeding areas inside the crustacean aggregation do
not immediately notice the approach of danger. Only one of them heard the alarm
signal given by a young male from the edge of the feeding area and managed to
gather his fry in his mouth unnoticed. The other males, who sensed the approach
of sharks, took action to save themselves too late. They begin to gather fry
together and hide. The only way to become less noticeable in open water away
from the coast is to freeze in the hope that the danger will pass by. But it
is too late to do this: while gathering the fry in their mouths, caragochromis
males unwittingly gave themselves away with movements and sounds, and the sharks
have noticed this.
A large carangochromis gathered hastily his brood in the mouth and did not immediately
see that one of the sharks was approaching him. The parental instinct demanded
of him, first of all, to protect the offspring, and the male did not rush into
flight until the last fry swam into his mouth. And so, he let the shark get
too close to him. Carangochromis is faster than the green shark, but the sharks
are superior in numbers and have better maneuverability. And this carangochromis
male has been starving for more than a week, brooding offspring in his mouth.
Therefore, his chances of salvation are much less than in a school of congeners.
One of the sharks chases the carangochromis male, but the fish made a quick
dash forward, escaping from its teeth. The second shark tried to grab the carangochromis
from below, but it rushed to the surface of the lake and swam, churning the
water with its tail. It managed to break away from the pursuit for a short while,
but after a few seconds the shark caught up with it. Sharp teeth of the predator
tore out a piece from the side of the carangochromis male, and the fish began
to thrash in pain, and blood gushed from the wound. Now sharks do not need other
prey - all their attention has turned to this individual. Along with the blood,
the carangochromis male loses its vitality, and two sharks easily catch up with
it. They seem to be playing cat and mouse with their prey, inflicting bite after
bite on the fish. Finally, the game ends: the sharp teeth of the green shark
cut off the tail of the caragochromis like a knife. The dying male did the last
thing he could do for his offspring – he opened his mouth and released the fry.
And then the jaws of one shark grabbed his torso and bit it in half. The second
shark pounces on the rags of meat from the torn body, and begins to tear at
it greedily. After the feast of two predators from the fish full of strength
a few minutes ago, only a head with an open mouth and bulging eyes remained,
which slowly plunges into the depths. Some of the fry raised by this male ended
up in the jaws of sharks along with the body of their father, but a significant
part of the fry survived the slaughter. They gathered in a flock in the depths,
frightened and doomed to inevitable death. Without paternal protection, they
will be quickly eaten by numerous predators: from planktonic crustaceans to
branchiochromis.
The third shark turned out to be not so lucky: it was noticed in time, and carangochromises
managed to gather their broods and flee. Green sharks, like their ancestors
of the human epoch, are doomed to be eternal wanderers: they do not have a swim
bladder and these fish drown if they stop. Therefore, their whole life is in
constant motion. Regardless of the success of the hunt, they leave the congestion
of crustaceans, in which the caragochromis offspring are raised, and swim further.
Soon their silhouettes disappear into the distance, and there is almost nothing
to remind the viewer of the drama that had just occurred moments ago. Only the
gradually weakening smell of fish blood and a flock of orphaned fry were evidence
of shark hunting.
After the predators left the battlefield, carangochromis males began to gather
again to feed their offspring. One by one, they return to the congestion of
crustaceans and take their places at a discreet distance from each other. Almost
all of them returned – except one, torn to pieces by the sharks. The young male,
first noticed the sharks, also returned here. He managed to keep his brood intact,
and now there is a room in the shoal of crustaceans to feed his offspring. After
making sure that the danger has passed, carangochromis males open their mouths
and release their fry to feed. It happens that life circumstances equalize the
probability of survival of the offspring both for an experienced strong male
who knows how to take his rightful place in the cycle of life, and for a novice
who raises his offspring for the first time.
Carangochromises feed only on live prey, which they catch themselves. In this
regard, green sharks are less picky, and with the equal pleasure they eat both
live fish and other animals, and carrion at the wide range of stages of decomposition.
Several days have passed since the drama enacted among the carangochromis males.
Some males have already fulfilled their parental duties and left their offspring,
giving it the opportunity to live independently. And other fishes took their
place, competing among themselves for living space. Their life goes on.
But for some of the inhabitants of the lake, life has come to an end. Heavy
rains fell, and the rivers that overflowed the banks carried into the lake many
corpses of animals that were taken by surprise by the flood and could not escape.
Among them there was an old bovipotamus. It was a large female, one of the main
ones in the herd. Her body could not withstand the parasitic infection, and
within a few weeks, she weakened quickly and even gave up her place in the hierarchy
of the herd to stronger competitors. Due to the help of the herd, eingana did
not have time to attack her, but the life of this beast was already coming to
an end. And then one afternoon, when a heavy tropical downpour rushed over the
lake, the heart of a huge beast stopped. The surrounding animals felt the death
of their relative: mooing anxiously, they sniffed the air and snorted, glancing
sideways at the dead body of the old female. They left the place of death of
a relative as quickly as possible, feeling instinctively that the smell of carrion
could attract dangerous animals. The river, at the mouth of which the animal
died, did the rest.
The carcass of a dead bovipotamus female sways on the surface of the water.
The wind and current carried it far from the coast, and now it is inaccessible
to coastal scavengers. The smell of meat, which has already begun to decompose,
attracts the attention of the inhabitants of the lake, who do not care how fresh
the meat is. Triangular back fins cut the surface of the water near the carcass
of bovipotamus – green sharks have come to the smell. Their backs are poorly
seen against the background of lake water, but from time to time in the depths
the white belly of the fish “sparkles”, when it makes a bend around the carcass.
Sharks behave very carefully – they as if convince once again that their prey
is really dead. Gradually, about three dozen sharks of various sizes gather
around the carcass of bovipotamus: from half-meter “adolescents” to “giants”
one and a half meters long. One fish reaches the length of one meter and seventy
five centimeters – it is exceptionally large in measurements of this dwarf species.
Green sharks seem as if being in indecision: who will take the first bite? They
swim closer and closer to the carcass as their number grows. Finally, the excitement
of the predators overcame some critical point and one of the fish clung to the
bovipotamus’ hide. Sharp teeth tear the skin and this was the signal for the
beginning of the feast. Dozens of fishes almost simultaneously pounced on the
carcass and begin to tear it up. The pressure of the predators is so strong
that the carcass of the bovipotamus literally spins in the water. Guts fall
out of its torn belly and several sharks immediately begin to pull at them,
greedily swallowing pieces. In an attempt to get its own piece of meat, one
of the sharks accelerated and literally slipped on its belly along the backs
of its congeners, slapping its tail from side to side. Once on top of the carcass,
it pulled out a piece of meat with its teeth and rolled back into the water.
Gradually, the soft tissues were eaten, and the carcass of bovipotamus began
to sink. There is still enough meat on the bones, so the sharks continue to
feast. They even crawl into the chest of bovipotamus, nibbling the soft tissues
on the inside of the ribs. The sharp teeth of predators easily tear the ligaments,
cut the cartilage and leave deep scratches on the bones.
Sharks are creatures ideally adapted to devouring carrion. But even they do
not have the opportunity to eat absolutely everything on the bones of a dead
bovipotamus. Therefore, they leave the carcass when there is too little soft
tissue left on it to bite off. The remains of the bovipotamus sinks down into
the depths of the lake, where bottom dwellers – small fish, crustaceans and
mollusks – will eat them. Even the bones of bovipotamus will be eaten away by
radulae of the mollusks and will gradually crumble to dust.
The shores of Lake Carpentaria have numerous many bays, where water is warmed
by scorching sun. In some bays flocks of birds roam, gathering duckweed from
the surface, or bovipotamuses graze, devouring floating plants. But there are
bays also, where it is dangerous to appear not only for small animals, but even
for adult bovipotamuses. Plants in such bays are broken and uprooted from the
bottom by animals that feel like masters of the situation in the ecosystem of
the lake. In such bays, real “rookeries” of einganas are formed. Well-fed snakes
come here to warm up properly and digest their prey in peace and under the protection
of their own kind.
In one of these bays, several dozen einganas have gathered. There are very few
young reptiles here, and most of the reptiles are real monsters having a length
of 7 to 15 meters. Well-fed, digesting their prey, they do not pay attention
to each other. In this condition, einganas are not aggressive towards their
relatives. The massive reptiles lie with only their backs out of the water,
and the sun warms their bodies. Such a cluster of einganas would frighten almost
everyone, but there is one creature that is not at all afraid of the tyrants
of the lake.
On the back of one of these snakes, as if along a living road, a tiny marsupial
shrew runs. It jumps over the strip of water where the rings of the reptile’s
body go into the depths. The snake’s body is a set table for it. The marsupial
shrew is looking for leeches that stick to the bodies of the giant reptiles.
Parasitic fish lice like to attach near the abrasions left by resisting prey.
All these creatures are delicacies for the marsupial shrew. Due to the speed
of its movements, the animal manages to grab them before they take flight. While
traveling along the back of an adult eingana, which has grown to a truly gigantic
size, the marsupial shrew has found a large leech. The worm has bitten through
the skin of the snake with its three jaws and is sated with its blood without
restriction. The marsupial shrew is a creature that shoots first and asks questions
later. Trigger happy and in a frenzy, it instantly grabs the body of the leech
with its sharp teeth and pulls the leech out of the skin of the eingana. The
leech, almost twice as long as the marsupial shrew, is in no hurry to detach
from the snake’s skin. Undaunted however, the marsupial shrew begins to bite
the leech’s body repeatedly causing the worm to twitch in agony. From the wounds
inflicted by the beast, the blood of eingana oozes, which the leech had managed
to consume. Finally, the marsupial shew closes its jaws right next to the leech’s
mouth sucker and decapitate the parasitic blood sucker. Blood spurts from the
inside of the leech, and the marsupial shrew begins to lick it greedily. Despite
its size, the marsupial shrew is a bloodthirsty predator. Having finished with
the drops of blood, the animal greedily grabs at the still wriggling leech,
and proceeds to devour it.
The lake provides food for all living things – from a tiny marsupial shrew to
a giant eingana. And all of these creatures are links in the food chain, equally
important for the balance of the ecosystem.
Bestiary |
Bristle-legged
shrimp (Planctoatyopsis setipes)
Order: Decapods (Decapoda)
Family: Atyids (Atyidae)
Reservoirs of Australia and New Guinea of Holocene epoch were rather poor in
true freshwater fishes. Their population developed basically from sea species,
adapted to life in fresh water, and from migratory species of fishes. Because
Australia at the moment of origin of orders and families of freshwater fishes
was separated from other continents by sea passages, it has had an effect on
its ichthyofauna which appreciably differs from ichthyofauna of near islands
and Asia.
In Neocene the fauna of seas has changed strongly: it is connected to fluctuations
of biomass of plankton and extinction of coral reeves. The fauna of fresh waters
has suffered less though species of fishes connected to sea biotopes, mostly
have died out. Therefore in Australia the nature had organized interesting experiment:
ecological niches of fishes were partly occupied with other animals, swimming
crustaceans.
Bristle-legged shrimp is one of such species occupying free ecological niches.
Absence of fishes filtering microscopic algae in reservoirs of the Australian
region has permitted this species of shrimps to reach this success. This pelagic
crustacean up to 5 cm long meets in big shoals in lakes at small depth. The
bristle-legged shrimp gathers food for itself with the help of filtering device
developed on forward legs. At shrimps of family Atyidae, known to humans, at
two forward pairs of walking legs the special adaptation for getting food was
developed: brushes of hairs sticking up in sides. With their help shrimp digs
out tiny edible animals, sifting through them sand, as through a sieve. At the
bristle-legged shrimp this filtering device is transformed for filtration of
plankton organisms and large algal cells from water. At the internal side of
legs brushes are especially strongly advanced.
Swimming in thickness of water, shrimp makes paddling movements by forward pairs
of legs. At the stroke brush gathers plankton from water and when the leg makes
return movement, feeding arms scrape from bristles paste of algal cells and
plankton, and push it into mouth. The basic swimming organ of this shrimp is
third pair of legs with wide blades (as in water beetles). In the representatives
of this family known in Holocene (for example, at Malayan wood shrimp Atyopsis
moluccensis) these legs served for keeping at the bottom in stream. In connection
with the passing to pelagic way of life function of these legs had changed.
Fifth pair of walking legs is thin and adapted to accurate movements. They serve
for clearing of gills of silt and suspension.
Body of the bristle-legged shrimp is sharp-nosed and streamline-shaped. This
crustacean constantly keeps in thickness of water, occasionally sitting on stalks
of floating plants for rest.
Short moments of pairing at these shrimps pass in thickness of water. The female
is little bit larger than the male, but in him the claw at the tip of rowing
leg is better advanced. Male swims up to the female from below, overturning
upside down, and clasps her body by rowing legs. He injects sperm in oviducts
of the female with the help of first pair of abdominal legs, and then swims
away. Female lays about hundred large eggs and bear them on abdominal legs during
some days. Development of this species includes the planktonic larva stage,
which transforms into tiny copy of adult animal after two month of life.
Young shrimps do not compete to adults for food: they live near coast in thickets
of plants. Their forage is large infusorians and rotifers; growing up, they
pass to feeding by small crustaceans and algae. Shrimps had reached length about
2 - 3 cm gather in schools and swim in thickness of water, and pass to adult
food. Having reached such length, they can have posterity.
Bristle-legged shrimp lives up to two-year-old age seldom.
In the rivers and lakes of Meganesia there are also close species of shrimps:
Bearded
shrimp (Pl. barbatus) is considerably more specialized species: it
eats almost exclusively algae, competing with plankton cladoceran crustaceans.
At its forward legs there are brushes of very rich thin bristles, permitting
to filter only rather tiny cells of algae, and only smallest plankton animals
- rotifers. This shrimp is rather small – length of its body is up to 3 cm.
Body of this crustacean is practically transparent with light greenish shade:
it helps to mask from possible predators among plankton algae. Because the food
source, used by this species, differs in big efficiency, bearded shrimp makes
big congestions. But its number strongly changes in various seasons proportionally
to amount of phytoplankton. Life expectancy of this species exceeds one year
seldom, but the young shrimp can breed already at the fifth week of life.
Needle-legged
shrimp (Pl. spinosus) as against to relatives is active predator eating
large plankton crustaceans (including larvae of other shrimps) and even small
fishes. Bristles on legs are hooked, large and thin – they are adapted to hooking
and keeping small catch, instead of algae filtering. Length of this shrimp is
up to 6 cm. The body is colored green with reddish-brown and black vertical
strips; on pair of swimming legs there are white longitudinal strips. It keeps
solitarily or in small changeable congestions in thickets of floating plants,
immediately attacking shrimps and small fishes. At times shrimps of this species
can have fights for catch, and as a result of which crustaceans can lose not
only catch, but also pair of legs moreover. Larvae of this species at first
eat microalgae, than catch in the beginning small plankton crustaceans, and
later small shrimps and fish fry.
Barracuda
prawn (Sphyraenolemon serripes)
Order: Decapods (Decapoda)
Family: Palaemonids (Palaemonidae)
Habitat: rivers and lakes of Northern Meganesia.
In seas of Neocene crustaceans compete to predatory fishes, have got good chance
during mass extinction when the global cataclysm had carried away to non-existence
the majority of predator species and has laid down survived species in rather
equal conditions. So, at the reeves of Pacific ocean formed by large bivalve
mollusks and algae, there are large predatory mantis shrimps. In freshwater
reservoirs of Meganesia the similar situation had taken place: the ichthyofauna
of this continent was considerably depleted during mass extinction, than decapods
have taken advantage. And here evolution showed to the world the new kind of
predator – the barracuda prawn.
It is rather large prawn – length of its flexible body is up to 30 cm. Its cephalothorax
is rather short: about a quarter of general length of animal, but pleon is very
large and muscled. In it there is plenty of muscles providing intense work of
swimming legs (pleopods). Swimming abdominal legs of this prawn are covered
with numerous hairs. During forward movement of leg hairs press to it and do
not interfere with movement, but in rowing time they form extensive rowing surface.
Pincers of barracuda prawn are well advanced: with their help this crustacean
seizes and kills catch: smaller shrimps and fishes. Pincers of this prawn are
rather large (their size is about half of body length), serrated at the cutting
edge. Seizing fish, the barracuda prawn pierces by teeth of pincers its spinal
cord, and at the caught shrimps breaks off abdominal nerve chain. It instantly
paralyses catch and deprives it of opportunity to resist. Walking legs and sharp
serrated mouth feet help predator to kill catch.
Eyes of barracuda prawn are very large, spherical, located on long stems. Facets
making these eyes are numerous, therefore prawn can distinguish even tiny details
of environmental district. In water inhabitancy the chemical feeling has not
less important role. Organs of chemical feeling (chemoreceptors) are placed
at the barracuda prawn on antennae. antennae of this prawn are as long, as body,
feather-like due to set of hairs (it considerably increases their sensitive
surface).
Barracuda prawn spends the most part of time in ambush – among thickets of floating
plants. As well as all crustaceans, it is not able to chase prey for a long
time, therefore it has selected optimal for crustacean physiology tactics of
ambuscader. In this connection at it cryptic colouring was developed: the basic
background color of body is yellowish-green with faltering longitudinal dark
green strips at the top side of body. The barracuda prawn clings to floating
plants upside down: thus it has practically full circular field of view.
Having noticed possible catch, barracuda prawn cautiously creeps to it, having
turned pincers together: probability of their hooking for plants during solving
throw is less so. When the planned prey appears close, prawn makes throw. Having
pushed by walking legs from plants, it starts to work intensively by swimming
legs, at once developing the big speed. Usually the chase lasts no more than
ten seconds – physiological opportunities of organism of crustacean do not permit
longer chase. If the first throw was unsuccessful, the prawn stops chase and
again hides in thickets. Usually only one throw from five ones is successful.
Having caught fish or shrimp, the barracuda prawn kills it by strong compression
of pincers and starts to eat. But it is not safe occupation: involved by smell
of blood, hungry neighbours gather, and at times fairly preyed food becomes
the property of the neighbour which simply had appeared in necessary place in
necessary time. Therefore the prawn tries to drag prey off in place, where it
will not be to found at once by competitors. Usually it hides in thicket of
plants and starts to eat catch hasty, beginning to eat softest parts. Barracuda
prawn simply throws out rests of catch, and they fall on bottom, becoming food
for other lake inhabitants.
Usually barracuda prawns live solitarily, banishing neighbours from territory
which they occupy. But from time to time under influence of breeding instinct
they become much more tolerant to some neighbours.
Males of this prawn species differ from females in smaller size. But at them
pincers and very long antennae are appreciably larger. It gives them certain
advantages to larger and strong female: in time of “acquaintance” it looks more
impressive, suppressing a little by demonstrations aggression of the female.
The female lays rather small amount of eggs: about hundred ones. But each egg
is rather large: its diameter is about 4 mm. After a fortnight incubating on
abdominal legs of the female from it not helpless plankton larva, but well advanced
young prawn hatch. It differs from adult representatives of species only in
underdeveloped pincers and very small size of body. Young prawns are predators
of their weight category: they eat plankton crustaceans and fry, gradually passing
to larger prey.
Sexual maturity at barracuda prawn comes at the age of half-year at length about
20 cm. After that growth rate of crustacean decreases, but time of intensive
breeding comes there. Each two months during almost three years the female bears
the next portion of eggs.
But barracuda prawns will never become most numerous inhabitants of Meganesian
lakes, and partly they are the reason of it. Among barracuda prawns at any age
the cannibalism is usual phenomenon, and because of it only rather few from
young prawns can live up to mature age.
Green
shark (Carcharhinus viridis)
Order: Carchariniform sharks (Carcharhiniformes)
Family: Requiem sharks (Carcharhinidae)
Habitat: Lake Carpentaria, waters off the coast.
Drawing by Sauron from FurNation
Several representatives of the fauna of Lake Carpentaria serve
as reminders of the marine past of lake. One of the inhabitants of Lake Carpentaria,
by its appearance, gives the impression that this lake is still a part of the
sea. The pointed fin appearing on the surface of the lake belongs to a shark.
The shark of Lake Carpentaria is a descendant of the bull shark (Carcharhinus
leucas), which lived in the seas surrounding Australia and New Guinea in human
epoch. Following the change of the habitat, the appearance of the descendants
of this shark changed, although it remains recognizable. This species of shark
is a real dwarf compared to its ancestors and relatives: the length of an adult
does not exceed one and a half meters. Dwarfism is associated with the limited
habitat – these sharks inhabit a closed reservoir and cannot go far into the
swamps surrounding the lake: this shark can hardly tolerate oxygen-poor water,
and in dirty water begins to “cough”, attempting to clear its gills from silt
and plant debris.
The color of the shark’s body gives this species its name – green shark. Typically,
the coloration of the fins and upper body is off-green with lighter areas while
the belly is white. The individual variability in the color of this species
is quite large – there are some individuals that are pure bluish green in coloration,
while other individuals vary wildly in coloration, from sporting piebald patterns
to almost completely black. The presence of greenish tints in the color is associated
with the peculiarities of their habitat: microscopic algae develop in the water
of the lake, giving it a characteristic greenish tint. Due to this specific
coloration, the green shark is less visible from afar.
In proportions, the green shark resembles its ancestor. It has a flattened head,
pointed fins, and heterocercal tail. The eyes of this shark are small and its
vision is not exceptionally good. In the waters of Lake Carpentaria, where microsopic
algae proliferate abundantly, vision plays a lesser role than in the open ocean.
The sense of smell in this species is very acute. Also, the green shark has
developed lateral line organs.
This species lives in the water column, diving to a depth of 30-40 meters. Most
often, green sharks live in the interior of the lake, but juveniles are often
found near the coast, where there is less danger of attack by adults of their
own species. In the search for food, adults occasionally approach the shores.
Like its ancestors, the green shark feeds on fish. In addition, this shark eats
dead animals, whose bodies are carried by rivers far into the lake. The green
shark often attacks juveniles of the large local eingana snake. Several adult
sharks are able to attack even a five-meter “adolescent” of this reptile, but
adult eingana individuals pose a direct threat to them – large eingana can easily
swallow an adult green shark whole. Therefore, the relationship of the green
shark and the eingana resembles a low-intensity war.
Green sharks live alone or in groups of up to five adults.
This species is viviparous, like its ancestor: the female gives birth to up
to four juveniles at a time. From the first minutes of life, they are already
fully independent and have relatively few enemies. One of the factors regulating
the number of this species is adult cannibalism.
Disk
rainbow fish (Discotaenia multicolor)
Order: Aterinoids (Ateriniformes)
Family: Rainbow fishes (Melanotaeniidae)
Habitat: freshwater reservoirs of Northern Meganesia, thickets of aquatic plants.
Movement of Australian continent to the north and its collision with New Guinea
had caused active processes of mountain forming which had transformed Arafura
Sea and Gulf of Carpentaria to lakes separated from each other and from ocean
by land areas. Rains and rivers had gradually filled these reservoirs with fresh
water, and salt sea water had filtered out from them in ocean through cracks
in rocks. Only lowermost layers of water in these large lakes have slightly
brackish water, as if in memory of that once they were a part of sea.
In reservoirs Meganesia continent of Neocene fishes prosper; these ones are
descendants of species inhabited this area in Holocene a long time ago. They
are mainly representatives of Aterinoid fish order - various descendants of
rainbow fishes (Melanotaenia) and forms related to them (however, among ichthyologists
there was also an opinion, that rainbow fishes belong to another order, to Mullets
(Mugiliformes)). Similarly to cichlids in Africa (in Holocene epoch) and to
Neocene live-bearing fishes of Caribbean Sea, rainbow fishes had evolved to
plenty of various species, mainly predators or omnivorous species.
Disk rainbow fish is some kind of “angelfish” among rainbow fishes. It is an
omnivorous fish about 10 - 15 cm long, living in thickets of plants. Here this
fish hides from enemies and searches for food – larvae of insects and freshwater
shrimps. Body of disk rainbow fish is short, but very high: fish at a sight
from side seems almost round, only head and tail break disk-like shape a little.
Such body shape is characteristic for fishes living among stalks of water plants
– having such constitution it is impossible to swim fast, but it is possible
to maneuver easily in rich thickets. The body of disk rainbow fish is colored
very brightly: scales on body have green metal shine, on operculum there is
red “neon” spot, allowing to identify neighbours (at males it is brighter, than
at females), and unpaired fins are transparent green with blue border on edge
of tail. Body is covered with narrow and twisting cross strips of black color:
it helps to mask among vertical stalks of plants.
The mouth of disk rainbow fish is small; it can extend to small tube: by such
mouth it is more conveniently to gather attaching larvae of midges and mosquitoes
making a basis of diet of this species from plant stalks.
Disk rainbow fishes breed, dropping eggs above thickets of small-leaved plants.
For spawning they gather to big shoals (up to 200 fishes and more). Males begin
school formation, gathering to groups and appealingly swimming above thickets
of water plants. Gradually new males and females join them. The school swims
above plants, from time to time quickening, synchronously turning and twirling.
Movements of school of fishes ready to spawning resemble fantastic bewitching
dance. Vital processes of separate individuals are synchronized so, and females
begin ready to spawn practically simultaneously. Each female in time of “common
dance” is surrounded by two - three males (usually there are more males than
females in school). Then at the culmination moment “dance” interrupts and prompt
race begins. Females spawn eggs, and males following them, fertilize them. Eggs
fall in thickets of plants, and fishes do not worry any more about their destiny.
Having spawned a portion of eggs, female has a rest any time, having replaced
race to “dance”, and then spawning repeats. Usually female has exhausted egg
stock, leaves school, hiding in thickets. But it does not worry males: from
vicinities new males and females swim to school. Such “dancing madness” proceeds
some days in succession, and then fishes gradually calm down and again live
reticent life in plants.
If eggs will not be eaten with numerous predators and simply foddies loving
gratuitous entertainment, in day from them tiny larvae will hatch. They hang
on plants about day (yet a yolk sac will resorb), and then turn to active gluttonous
fry. At the age of half-year young fish has length about 5 cm and colouring,
characteristic for adult fishes (only without red spots on operculums), and
at seven-month age it already can breed.
Wide-mouthed
rainbow pike (Esocitaenia angustistoma)
Order: Aterinoid fishes (Ateriniformes)
Family: Rainbow fishes (Melanotaeniidae)
Habitat: freshwater reservoirs of Northern Meganesia (Carpentaria Lake), thickets
of underwater plants.
Being out of competition in various conditions of inhabiting, species of live
organisms quickly divides to some new forms, occupying various habitats, weakening
thus a competition among themselves. Such process is named “adaptive radiation”.
In Australian-New Guinean region such phenomenon is shown by fishes: representatives
of family of rainbow fishes. Among them species had mastered most various habitats
and habit of life have appeared. One of species of this family, the wide-mouthed
rainbow pike, had turned to active predator of brackish lake formed at the place
of Gulf of Carpentaria.
This solitary species of fishes had occupied ecological niche of pikes and other
ambush predators. In this connection at the rainbow pike the characteristic
shape was formed. Body of fish is oblong and almost cylindrical; length is up
to 60 - 80 m. Tail fin is two-lobed, wide and short. Unpaired fins are shifted
in back half of body, prickly and soft back fins are connected. Abdominal fins
are very short, located approximately under pectoral ones. Rainbow pike swims
reluctantly, but can stand per many hours in ambush at the bottom, waiting while
catch itself will approach to it close enough to prey it.
Head at this fish is large with wide mouth, extending to short tube. On jawsthere
are about hundred small needle-like teeth permitting to keep easily slippery
fish or firm shrimp (they make a basis of food of rainbow pike).
The body of this fish is colored with “marble” pattern imitating stones overgrown
by seaweed and solar patches of light on them: the basic background is sandy-yellow
with cross green and white irregular-shaped “dabs”. At each individual they
form unique individual pattern. Besides the shade of coloring can vary depending
on color of environmental site of bottom: from almost entirely green color with
white and yellowish-green spots up to almost monochromic sandy-yellow color
with white “dabs”. At night the fish as if appreciates ancestral colouring:
it turns pale, and along the middle line of body the clear black longitudinal
strip appears: ancestors of rainbow pike were australian and New Giunean rainbow
fishes (Melanotaenia), named so for this feature (“Melanotaenia” in Latin means
“black-striped”: many species have longitudinal black strip in colouring).
Each fish occupies at the bottom the certain territory, preserving it against
neighbours. As borders of territories various underwater objects, and simple
sites of the bottom, not overgrown by plants, serve. If on border the neighbour
appears, the owner of territory swims up from thickets, uttering series of clicks.
Usually such signal happens enough to drive the stranger off. The fish banishes
especially persistent newcomers by sharp throw, braking and turning off aside
near to stranger. If the stranger is not going to leave, the turn and ramming
impact by snout in area of operculum follows.
During spawning borders of territories as if cease to exist: rainbow pikes earlier
were selfish and bilious singles, gather to schools of some tens fishes. Spawning
is stimulated with rains freshened the top layer of lake water, and also with
bright sunlight. Males shine with bright red fins and golden spots on sides.
Fishes spawn in groups, spreading eggs above leaves of aquatic plants near coast.
Spawning passes roughly: fishes keen on pursuit one after another jump out from
water at meter height and plop down back with loud splash. Each female can spawn
approximately 500 - 600 grains of roe for one breeding cycle. After the ending
of spawning fishes swim out to their sites, and each of them precisely remembers
borders of the possession and ruthlessly expels strangers, which had time to
lodge at this site of bottom, from the territory. Approximately month later
spawning repeats. But, despite of such fertility, fry of rainbow pikes meet
among plants in shallow waters of Carpentaria Lake much less often, than fry
of other species of fishes.
Eggs develop within approximately two weeks. Because fishes do not care of posterity,
for this time the most part of eggs appear had eaten by various inhabitants
of lake. Larvae grow disjointedly, and among fry of rainbow pike cannibalism
is not a rarity, and fry frequently become preys of adult fishes. If the young
fish managed to reach half-year age and length about 20 cm, it has quite good
chances to live up to 10 - 12 years – it is the age limit of wide-mouthed rainbow
pikes.
Largemouth
carangochromis (Carangochromis macropomum)
Order: Perciformes (Perciformes), suborder Labroidei
Family: Cichlids (Cichlidae)
Habitat: Northern Meganesia, Lake Carpentaria, areas away from the coast.
In the human era, numerous fish species were introduced to New Guinea, which
were planned to be used as commercial fish. After the extinction of mankind,
some of the introduced species became extinct without any descendants, but other
species managed to survive and evolve. Their descendants occupied various ecological
niches in the ecosystems of the Neocene.
In the early stages of the lake formation, the descendants of marine fish dominated
Lake Carpentaria, but later the waters of the lake desalinated, causing their
replacing by descendants of freshwater species. Among the fish that inhabit
the lake, fish of the cichlid family have achieved some success. Due to their
peculiar way of breeding, some of them managed to leave the coastal zone and
came to inhabit open waters. The ancestor of various cichlids of Lake Carpentaria
is the Mozambican tilapia (Oreochromis mossambicus (Tilapia mossambica)), introduced
to New Guinea. This unpretentious species quickly settled in all available habitats,
and as a result of evolution gave rise to a whole group of species differing
from each other in behavior and ecology.
Avoiding competition in coastal habitats, one of the tilapia descendants adopted
a pelagic lifestyle far from the shores of the lake. It acquired a streamlined
body and developed into an excellent swimmer. This is how the large-mouthed
carangochromis appeared, one of the characteristic inhabitants of Lake Carpentaria.
This species of fish only accidentally enters the coastal areas, preferring
the vast, open waters of the lake’s center. The appearance of the carangochromis
shows that it is a fish capable of great bursts of speed. The head of the fish
is relatively large and flattened, with a wide mouth that can be extended into
a tube due to elastic membranes connecting the jaw bones. The body is torpedo-shaped
and muscular, with a strong caudal peduncle; caudal fin has a crescent shape.
It gives Caranochromis a resemblance to fast-swimming trevallies (Caranx) –
marine fish of the human epoch. The length of an adult fish is up to 60 cm,
males are larger and more massive than females.
The dorsal and anal fins of the fish are shifted back and have rigid fin rays.
The spiny part of the dorsal fin is reduced to some separate spines with a rudimentary
membrane stretched between the back and the posterior edge of such spine. On
the back of the fish, there are up to ten such spines. The pectoral fins are
narrow and pointed. The pelvic fins are shifted forward almost under the base
of the pectorals; they are narrow and resilient. During swimming, the pelvic
fins fold along the body, forming a kind of keel on the abdomen.
The body color of this fish is bluish green, with a lighter belly; there is
a dark spot on the head between the eyes. During the mating season in the male,
this spot increases in size, stretching from almost the tip of the snout to
the back of the head. Male also differs from female by a characteristic fatty
build-up on the head. In order not to interfere with the movement of the fish,
this outgrowth has the shape of a ridge compressed from the sides and stretched
from the bridge of the nose to the middle of the back (to the first spines of
the dorsal fin); there is a weakly pronounced keel on the upper part of the
ridge.
This type of fish is an active predator. The teeth of the carangochromis are
exceedingly small, and the fish captures its prey by sucking it in with its
mouth, which opens in the form of a tube. Fish and pelagic shrimps are the carangochromis’s
primary food sources. Carangochromis live in schools of up to twenty individuals.
It is the flexibility of their reproductive behavior that has allowed this species
to leave the coastal zone, stopping spawning eggs in the nesting hole at the
bottom. These fish incubate their eggs in their mouths. This is done by the
male, for whom the fat build-up on the head serves, among other things, as a
supply of nutrients, allowing the male to save energy while he raises his young.
During the breeding season, the scales of the male become an intense shade of
blue, while the dark spot on his head expands a lot. At the same time, the lips
of the male thicken and become white. The male, ready for spawning, displays
himself to the females, spreading his fins and shaking with his whole body in
front of the chosen female. The formed pair gradually begins to keep apart from
other fishes of the school. Spawning in this species occurs quickly and without
long courtship rituals. The female spawns a portion of eggs into the water,
and the male immediately fertilizes them and catches them with his mouth. In
total, the female spawns up to 500 eggs in 3-4 batches. Having gathered the
clutch, the male leaves the school. At this time his behavior changes: he stops
feeding and stays in the upper layers of water, at a depth of up to a meter
from the surface. Sometimes several males incubating eggs unite into the school.
Incubation takes up to 5 days, and larvae spend the same time in male’s mouth,
while turning into fry. During the first month of their life, the male takes
care of the juveniles: he hides them in his mouth in case of danger and transfers
them to places rich in food. Small cladocerans living in the upper layers of
water serve as food for the young. Fry of this species have a characteristic
cross-striped color – gray with black stripes. These stripes fade with age.
Young fish reach maturity in the second year of life.
Branchiochromis
(Branchiochromis pelagicus)
Order: Percoid fishes (Perciformes), suborder Labroidei
Family: Cichlids (Cichlidae)
Habitat: Northern Meganesia, Lake Carpentaria, areas far from the coast.
The descendants of the Mozambican tilapia (Oreochromis mossambicus), introduced
by humans to New Guinea, have mastered various ecological niches, differing
wildly from one another in terms of lifestyle. Lake Carpentaria is inhabited
by several cichlid species descended from a common ancestor. One of them is
a large carangochromis, an active predator. Another type of pelagic lake cichlid
is the small and numerous branchiochromis.
Unlike its predatory neighbor, branchiochromis feeds on small crustaceans and
fish fry that live in the water column. This type of cichlid is remarkable in
its large mouth and dense gill rakers – these are the adaptations for filtering
planktonic organisms while in motion. Schools of branchiochromis swim far from
the coast. Having found an untapped food source, these cichlids are one of the
most abundant fish species in Lake Carpentaria.
Branchiochromis is a relatively small species; the length of an adult is no
more than 15 cm. Due to the development of the filtration apparatus the head
of this fish is large – about one fifth of its total length, excluding the fins.
The body is elongated and torpedo-shaped. The spiny part of the dorsal fin is
low, with shortened rays. The anal fin and the soft part of the dorsal fin are
large and pointed. In males, the tip of the dorsal fin is extended. The caudal
peduncle is short and deep while the caudal fin is rigid and crescent. Branchiochromis
is a good swimmer, capable of reaching speeds up to 40 km/h.
The color of the branchiochromis body is typical for schooling fish – silvery-gray
with metallic sheen and numerous longitudinal dark blue stripes. The eyes are
large and silvery; the lips are white. The fins are transparent with a grayish
tint; the extended tip of the dorsal fin of the male is bluish in coloration,
which becomes much brighter during courtship.
Branchiochromis fishes gather in large schools numbering several thousand individuals
of approximately the same size and age. Feeding fish form a crescent-shaped
line and surround the congestion of planktonic crustaceans, gradually closing
the edges of the school and driving their prey into a dense ball. Being under
attack, these fishes gather in a spherical school.
Branchiochromis feeds mainly on zooplankton. In the dense accumulation of crustaceans,
they swim slowly, gulping and filtering separate portions of water through their
gills. In sparse but extended congestions of crustaceans, fish swim with open
mouths and gill covers, filtering the prey while in motion. The open mouth of
branchiochromis expands into a tube. In addition to crustaceans, branchiochromis
fishes also feed on planktonic algae, which they filter out together with the
crustaceans or simply during the movement.
Reproduction of these fish takes place in a school. Males and females form pairs
and stay together for some time inside the flock. If a school has to spread
out to the sides, fleeing large predators, both fish from a pair will spend
a great deal of time searching for each other when the school reunites. The
presence of pairs in the flock is an incentive for spawning. As pairs form in
the school the overall excitement grows – fishes exchange signals, synchronizing
their physiological state, and some days later the spawning begins. Males get
brighter, while their heads turs black, and against this background, their white
lips stand out well. In contrast, the female’s head turns into a shade of gray.
The stripes on the body of fish of both sexes become wider and darker. As the
male and female in the pair circle around each other, the male displays to the
female a brightly colored tip of his dorsal fin. The eggs are spawned directly
into the water. Female fertility is up to 200 eggs.
The fertilized eggs are gathered by fishes of both sexes; the clutch is then
incubated in the mouth. Male and female evenly distribute the clutch, and after
that the pair breaks up. Each fish independently takes care of its part of the
clutch. Incubating fish leave the general school and form small schools in areas
where planktonic invertebrates form congestions. Egg incubation lasts 3 days
and the offspring leave the parent’s mouth at the age of one week. For about
two weeks, an adult fish takes care of the offspring, after which the fry move
on to an independent life. At this time, there is a high probability that adult
relatives can eat the juveniles themselves.
Branchiochromis reaches maturity at the age of 14-15 months.
Saw-nosed
crocodile (Pristisuchus serratorostris)
Order: Crocodiles (Crocodilia)
Family: Saw-nosed crocodiles (Pristisuchidae)
Habitat: brackish sea gulfs, mouths of rivers of South-Eastern Asia,
Indonesia, Meganesia (it is especially numerous in Arafura Lake).
In warmed up extensive shallow freshened coastal lagoons of
coast of South-Eastern Asia life boils over. Here it is a lot of forage, algae,
plankton; it ideal place for feeding and fatting. Besides water has the lowered
salinity that reduces expenses of forces to osmotic regulation. Here numerous
oceanic fishes come to food up. They frequently swim in big dense shoals, relying
to the best passive protection by the large number. It is meaningful frequently,
but not always. Suddenly narrow long shadow runs into such dense shoal. Narrow
long flat “saber”, armed at edges by big sharp thorns, starts operate barbarously
here and there, harming strongly incautious fishes. In shoal the panic begins.
The density of the fish shoal plays not on a hand to its members; they rush,
come across against each other, are thrown here and there and in larger number
get under ruthless impact of terrible weapon. Eventually the shoal blurs in
sides, leaving about ten twitching, bleeding profusely, and crippled fishes.
Predator quietly begins meal.
It is the saw-nosed crocodile growing up to length up to 3 m. It is one of few
species of crocodiles had survived up to this time. It is very much specialized
one and it seems similar to gavial. But gavial had died out, not having left
descendants: its number was decreased by people, and specialization did not
promote a survival in epoch of mass extinction. The saw-nosed crocodile descends
from any Asian species of crocodiles had survived in epoch of global cataclysms.
Other species of crocodiles, the furious sharkodile,
lives in tropics of Pacific Ocean. In the majority of tropical rivers the place
of water predator was occupied by fishes (up to sharks!) and lizards. Therefore
the saw-nosed crocodile lives any more not in rivers, but at the coast of sea
lagoons where there are more fish frequently keeping in dense shoals.
It is perfectly adapted to feeding by fishes. At this reptile there are narrow
graceful body, wide tail and extended narrow jaws. Long teeth at its long and
sword-shaped top jaw grow originally: they are directed perpendicularly sideways.
As a result the “saw” is formed like existing at Holocene saw-fishes one. It
also operates by this saw in shoal of fishes, having rushed into its thicket
and making sharp jerks by head here and there, horizontally and aslantly. The
small part of teeth of usual shape and smaller by size, is visible in intervals
between “saws jags” and serves for capture of catch. On the bottom jaw all teeth
are small and “standard”. During hunting jaws are closed, and resistance of
water is minimal. The body of this crocodile is not covered any more by heavy
osseous armour as at its far ancestors, it is not necessary any more to this
species to protect intensively, it is more necessary to have speed and maneuverability.
This reptile is covered with strong elastic skin. Rudiments of armour are submitted
partly by back and occipital scutes. The skin has greenish-grey color with fuzzy
cross-striped pattern and lighter belly, masking it in a thickness of water
have been lit up by solar patches of light in shallow water. Its paws are weaker,
than at ancestors, and it never leaves far from water. But a lot of time it
spends in water, but quite often it can be seen at the coast where it is basking
at sunny place. Especially numerous groups of crocodiles of this species gather
at sandy shallows in river estuaries.
Having got warm, crocodile starts to hunt, making the way to water along fenny
marshy coast. Its paws are weak, and frequently the animal simply slides on
dirt on stomach, pushing by them. It quickly and dexterously swims, using rather
wide powerful tail. In the beginning, having noticed suitable fish shoal, it
imperceptibly creeps to fishes, then as the knife, promptly runs into it and
swings the weapon. Having sated, the reptile creeps out to the coast and has
solar baths. The terrible blow of jaws armed with sharp teeth and a powerful
tail waits predator dared to interrupt its rest. However large or pack predators
occasionally nevertheless manage to win it, because paws of the crocodile are
not such powerful, and skin is not so is strong as at crocodiles of Holocene.
It breeds like all crocodiles: the female lays eggs in nest dug on coast in
silt and grass, and protects posterity. Young ones feed in shallow water in
thickets, mainly with medium-sized fishes, and eat as usual crocodiles; they
start to master the characteristic habit of hunting at the age of three years.
In early age they can become chase of predators.
Adult individuals are territorial; they supervise sites at the coast do not
supposing contenders. However this division is indistinct as at the seal rookery,
and each time it is made anew in process of returning animals from fishing.
Sorting out of relationships is usually strictly ritualized, and is limited
to that contenders raise upwards the top jaw, looking who is larger.
During courtship fights males are not so ceremonious, and easily can put to
each other an injury by “saws” armed with teeth, when swing them before the
contender, and quite often impacts strikes.
The life duration may account about 70 years.
This reptile species was discovered by Arseny Zolotnikov, a forum member.
Eingana
(Eingana archonta)
Order: Squamates (Squamata), suborder Snakes (Serpentes)
Family: Pythons (Pythonidae)
Habitat: Meganesia, Lake Carpentaria and nearby swamps and lakes.
In the prehistoric era, a python of the genus Liasis reached a length of 11
meters and lived in Australia. In human epoch, its relatives reached more modest
sizes – a maximum of only 6 meters. After the disappearance of man, one species
of Australian python repeated the evolutionary path of this extinct species
and turned into an even larger giant, simultaneously becoming the largest snake
of Neocene Earth.
Eingana is a reptile species that is much larger than anaconda of the human
era. Adult eingana reaches 20 meters in length with a body width of up to a
meter. These reptiles can hunt exceptionally large prey and can easily swallow
animals weighing up to 150 kgs. Its large size limits this snake’s ability to
move on land, but eingana has got rid of this difficulty by turning into an
aquatic animal. Due to its large size, this reptile rarely appears on land –
those found on dry land are usually juveniles looking to settle in other bodies
of water.
Despite the thickness of its body, the Eingana looks like a harmoniously built
animal due to its great length. It moves easily in the water thanks to its tail,
which is slightly compressed from the sides. The head of the reptile is short
and wide, its small eyes shifted upward. The reptile’s nostrils, equipped with
leathery valves, are also shifted upward. Thanks to this, eingana can hide in
ambush underwater, exposing only a small part of its head above the water surface.
The body of this reptile is an olive-green color with darker irregular spots
forming a pattern similar to the glare of sunlight on the bottom. Due to this
color, the eingana can disguise itself on the bottom near the coast, waiting
for suitable prey to appear.
This species is able to cope with almost any inhabitant of Lake Carpentaria
and the surrounding forests that comes to the water. Eingana hunts bovipotamuses
in the water, and also ambushes near watering holes and drowns land animals
in the water. Eingana bites the caught prey and holds it with its long, backward
curving teeth. Wrapping its body around its prey, the reptile makes it difficult
for it to breathe. If the prey is caught in deep enough water, eingana will
simply drown the prey, keeping it under water with its powerful coils.
In terms of reproduction, eingana is quite different from its python ancestors
and is more similar to boas: it is a viviparous species. Such an adaptation
developed during the transition of the animal to a fully aquatic lifestyle and
allows the female not to undertake dangerous trips on land. Eingana’s pregnancy
lasts about 8 months; pregnant females spend most of their time in shallow waters,
and during this time they hunt much less often than usual, especially in the
second half of pregnancy. In the process of development, the embryos receive
nutrition from the mother’s body through a kind of placenta, so young snakes
at birth are about 2 meters long. The female gives birth to up to 15-20 juveniles
at the same time. The juveniles are born in the water, and the young snakes
break the embryonic membranes and rise to the surface to breathe on their own.
The first prey of young snakes is water birds. As einganas grow, they begin
to hunt large mammals.
The idea of the existence of this species of snake was proposed by Tim Morris, Adelaide, Australia.
Scoopbeak
(Anserostrum bicolor)
Order: Anserine birds (Anseriformes)
Family: Spoonbill geese (Anserostridae)
Habitat: shallow waters of lakes of Southern and Eastern Asia, Northern Africa,
Indonesia and Northern Meganesia.
Humid and warm climate of Neocene had caused special habitats: shallow-water
reservoirs with well warmed water. Such reservoirs are especially numerous in
Northern Africa where Nile, having turned to the west, had humidified Sahara
Desert and had transformed it to savanna rich in life. In such shallow streams
and ponds seaweed and flowering aquatic plants plentifully grow, and the surface
of such reservoirs is richly overgrown with duckweed (Lemna). Abundance of forage
creates favorable conditions for ones managed its gathering. Small fishes and
crustaceans basically inhabit such reservoirs. Carpet of seaweed at the bottom
involves some large herbivorous fishes but in such
reservoirs it is possible to meet other larger animals.
On such spread stream with slow current the bird with long neck and thin legs
wanders. Lowering bi-colored beak in water this bird drives it to sides gathering
from surface duckweed the live creatures have clung to it. When the bird lifts
head, it is visible, as the skinny pouch under beak is full of water. Slightly
having stirred by head bird pours water out from mouth and swallows something.
Then it again lowers beak in water and repeats its movements. It is the scoopbeak,
the descendant of any geese among species inhabited Northern Africa. Bird is
not solitary one: beside in shallow water its neighbours wander highly lifting
legs up at each step.
By constitution scoopbeak is similar to some storks. Height of bird from toes
up to crown is about 120 cm; weight is up to 5 kgs. Body feathering is white,
only on wing flexion there are black feathers forming original “epaulets”. Head
is covered from above with black feathers. The bottom part of head (from eye
level) and throat are featherless and covered with smooth gray-blue skin. The
long beak of bird is colored two colors: top jaw is carrot-orange-colored with
yellowish tip, bottom one is dark-grey. At males in the basis of beak there
is “knob” characteristic for anserine birds.
Wings of bird are wide and rounded: scoopbeak is excellent flyer and also can
make long migrations choosing for reservoirs plentiful in food. Tail of bird
is short and fan-shaped. Legs are long and covered with black skin. Between
toes there is rudimentary palama getting to scoopbeaks from geese, their ancestors.
This bird has also inherited from them characteristic voice: resonant honk.
Scoopbeak eats algae, plankton crustaceans and fry gathering it from water surface
with the help of characteristic lateral movements of head. The beak of bird
is specialized for such feeding by tiny organisms forming congestions: it is
long, bottom jaw is grooved, and muscled tongue is located in it. The end of
beak is flattened and wide. Along edge of corneous cover of beak there is filtering
device of numerous bristles arranged by slanting lines. Long tongue is attached
to mouth bottom. At its edges also lines of corneous bristles pass. The top
part of gullet of bird has great number of elastic ring muscles which can strongly
stretch and retract fast.
For feeding bird lowers head and moves it from side to another in parallel to
water surface (the bottom jaw is submerged in water). During head movements
water is gathering in throat pouch; then scoopbeak lifts head above water and
by retraction of ring muscles pours out water of throat. Thus it flows through
filtering device of beak, and all eatable organisms stay in bird’s mouth. During
feeding process bird line stretch by a half moon and birds move to the coast
driving fishes and crustaceans to shallow water. After that they simply scoop
a congestion of food.
These birds live at freshwater reservoirs and migrate within limits of tropical
zone of Old World and Australia. They stay for a long time only at large reservoirs
nestind there in the beginning of dry season. They do it not casually: abundance
of sunlight and plenty of organic substance in water results in mass development
of plankton – the main food source of these birds. Reservoirs do not dry up
completely: in dry season rather frequently there are rains filling up stocks
of water.
Scoopbeak nests on the ground among reed-beds or on river islands in colonies
numbering up to 50 - 100 birds. Pairs formed to some seasons and sometimes keep
to all life as at geese. Birds formed pair prefer to feed together and spend
a lot of time making to each other signs of attention. In nesting season pair
builds nest of grass and thin rods in common.
In clutch of scoopbeaks there are 4 – 5 large eggs with spotty shell. Nestlings
hatch after 28 days of incubating. They hath with opened eyes, covered with
yellowish-grey down with brown longitudinal strips on cheeks, nape, sides and
back. Their beaks are already rather wide and they can eat small organisms.
As against to adult birds nestlings swim good: they have palamas between toes.
As soon as nestlings hatch and dry, they abandon nest for ever.
The young growth feeds on surface of water filtering by beak the uppermost layer
where plankton organisms concentrate. Both parents preserve hatch self-denyingly
protecting chicks from enemies. But all the same the significant part of young
birds perishes in teeth of large predatory fishes and reptiles inhabiting rivers
and ponds. When young birds will grow up and start to fledge adult members of
colony arrange collective feeding: having stretched to line adult birds drive
fry and larvae of freshwater shrimps to coast and towards to them from land
young birds walk. First time young birds can swim but later it is more and mare
difficult to do it for them: legs increase and palama decreases. At last young
birds in grey feathering with black beaks cease to swim and join adults starting
to wander in shallow water together. But sooner or later parents will banish
young growth, and juvenile scoopbeaks will have to live independent life in
barchelor flights. At the third year of life they will cast the coat and will
get the characteristic feathering of adult birds; and the top part of beak will
color orange. Then young birds can form pairs which will be kept at them, probably,
for all life.
Stegoechidna
(Stegotachyglossus armatus)
Order: Monotremes (Monotremata)
Family: Echidnas (Tachyglossidae)
Habitat: forests and scrub of Northern and Eastern Meganesia.
Picture by Alexander Smyslov
Picture by Eugeny
Hontor, tat shows the overall idea of the animal's appearance more exact,
but having mistakes in depiction of its hind legs and tail
During the Cenozoic era the branch of monotreme mammals gradually
declined. Their variety gradually became lesser, and the habitat area narrowed
steadily. In human epoch the area of monotremes included only Australia and
New Guinea. But in these districts monotremes were competitive enough, and strongly
kept their place in ecosystems. Before the occurrence of people in Australia
the sheep-sized giant echidna existed in this continent. But human activity
had quickly resulted in extinction of these animals.
Having survived in human epoch, monotremes had proved their viability. In Neocene
representatives of this group of animals had formed a number of new species.
The apopheosis of evolution of this order of mammals is the largest species
of ever living monotremes, the inhabitant of rainforests at the north and east
of Meganesia. This animal is named stegoechidna.
The appearance of stegoechidna causes memoirs on epoch of dinosaurs. This is
a large four-footed animal, growing to about one and a half meters high at a
shoulder and weighting up to 200 kgs. It has a massive constitution and thick
short tail. Back and tail of this animal bristle up with corneous prickles and
scales, providing reliable protection against an attack of predator. Along the
back of animal pointed and long corneous spikes of reddish color grow, gradually
transforming to reddish plates on tail and hips. The skin of this animal about
2 sm thick is covered with short and rough black wool. The top layer of skin
cornificates, forming additional protection.
Head of stegoechidna is narrow and long, with slightly curved “Roman” snout
and small mouth. The bottom jaw is mostly long and thin, and only in its basis
bones extend. In these places on bottom jaw thick corneous plates, with which
help the animal crushes forage, develop. At this animal there are small eyes,
and also external auricles are not present. Sight and hearing at stegoechidna
are weak, but sense of smell is very keen.
This animal lives in underbrush and moves, supporting on external part of hand
and having turned up huge forepaw claws. With their help animal digs ground
in searches of forage. As against to its smaller relatives, this animal is omnivorous,
and the significant part of ration of stegoechidna is made of vegetative food
– tubers and roots of plants. Animal digs them out by monstrous claws of forepaws,
takes by small mouth and pounds between ridge corneous plates growing on jaws
and tongue basement. Also it willingly eats earthworms, grubs and fruits fallen
from trees.
Stegoechidna has very small brain, and its behaviour differs in primitiveness.
It leads a solitary way of life, and shows interest to relatives only during
the breeding time.
These animals breed at presence of enough of food, usually in late spring or
in the beginning of summer. The female lays three large eggs with dense shell
into the brooding pouch forming at this time. The incubation lasts about two
months. Newborn cubs eat milky secretions of skin within three months, and leave
a pouch rather well developed. Having left the pouch, they follow the mother
and eat larvae of insects and other invertebrates, yet become advanced enough
to digest vegetative food. Young animals abandon mother at the age of about
5 months. They reach sexual maturity at the 6-th year of life.
Life expectancy of stegoechidna reaches 60 – 70 years. The adult animal does
not have enemies – only few predators can bite through its thick skin. However,
the young animals have recently left the pouch are protected much more poorly,
than adult individuals – corneous scales and spikes at them develop within approximately
one month after they leave a parental pouch. At this age the greatest number
of animals of this species perishes.
This species of animals was discovered by Tim Morris, Adelaide, Australia.
Marsupial
shrew (Nanantechinus aquadromeus)
Order: Dasyuromorphia (Dasyuromorphia)
Family: Dasyurids (Dasyuridae)
Habitat: Northern and Eastern Meganesia, river walleys, lakes and bogs.
Picture by Eugeny Hontor
Till the Cenozoic, before the appearing of man and his satellites
from among placentary mammals, marsupial mammals of Australia had developed
practically all accessible ecological niches, having formed a plenty of various
species. But one environment had remained completely inaccessible for them –
water habitats were those ones. Among Australian marsupials there are no analogues
of otters, seals or beavers. The brooding pouch, the refuge for young growth
for long weeks, had made development of water inhabitancy impossible for marsupials.
Therefore in Cenozoic in Australia the vacant place of large water vertebrates
was shared by birds, turtles, platypuses and rodents.
In Neocene marsupials had made one original attempt to develop water habitats.
Floating plants covering with leaves and stalks a surface of reservoirs, became
the house for one such creature. At the end of day and at the early morning
on the surface of carpet of floating plants it is possible to notice this creature,
managed to find the compromise between presence of brooding pouch and semi-aquatic
habit of life. It is tiny marsupial shrew - one of tiniest mammals of Neocene.
Length of body of this creature may be about 4 cm; tail is about 2 cm long.
The body constitution of marsupial shrew is very graceful; these small mammals
are similar to shrews with long legs. Back legs of this animal are little bit
longer than front ones. Head is rather large, with wide rounded ears. The muzzle
is long, extended to mobile proboscis, on each side of which thin whiskers stick
up. The marsupial shrew is the descendant of one of small species of marsupial
mice (Antechinus).
As this animal lives in areas with a warm climate, its wool is short and rigid.
It is colored light yellow, almost white color – it protects small mammal from
overheat. The body temperature at the marsupial shrew is changeable: at night
the animal is hidden among plants and runs into original catalepsy during which
the body temperature lowers down to ambient temperature. At this time the marsupial
shrew is rather languid, therefore it tries to find a reliable place where it
will be not found by predator. Sometimes for spending the night the animal even
gets into buds of water lilies which are closed for night, but do not immerse
into the water. In hottest time of day marsupial shrew is also hidden in shadow
to avoid overheat, but thus its temperature does not fall.
Fingers and toes of animal are bordered by “brushes” of hairs, and marsupial
shrew greases them with fat secretions of anal glands. Due to it hairs on paws
become not moistened, that permits this tiny creature to live on the surface
of reservoirs. It quickly runs on floating water plants, and even can run small
distances on the surface of water, quickly splashing on it by paws like the
basilisk lizard (Basiliscus) known in Holocene epoch. Basically, young animals
and adult males which are smaller, rather than females approximately to 30 –
40% are able to do it. Males and females without cubs can even dive for some
seconds. The female, especially one with cubs, does not risk to run on water
and to dive. It keeps on floating plants where it is easier to find forage and
to hide from enemies.
At this creature there are very sharp teeth: marsupial shrew is a gluttonous
predator, and devours for day twice more food, than it weighs itself. It eats
insects and their larvae, and also small shrimps. The animal catches them, immersing
head and forward part of body under water. Due to small size marsupial shrew
catches larvae of mosquitoes in leaf axils of floating plants – this animal
alongside with fishes and predatory insects controls the amount of mosquitoes
in damp districts. Also it can catch fish fry hiding among plants, and even
attacks small crabs.
Marsupial shrew lives in conditions where seasonal prevalence of climate rather
feebly marked; therefore it breeds the year round. The brooding pouch at it
is reduced up to two longitudinal plicas in groin area, bordering nipples from
sides. In litter it may be only 3 – 5 cubs developing very quickly. At monthly
age they already creep on back of the female, and in two months abandon mother.
One – two weeks later the female is ready to reproduction again. Sexual maturity
at young animals becomes at the age of three months. Life expectancy of the
marsupial shrew is more, rather than at placentary mammals of similar size with
constant body temperature: it may amount about two years. It is the result of
night catalepsy which is slowing down the “combustion” of its organism.
The idea about the existence of this animal is stated by
Tim Morris,
Adelaide, Australia, at the basis of idea of Dougal Dixon.
Bovipotamus
(Neobubalis lacustris)
Order: Artiodactyls (Artiodactyla)
Family: Bovids (Bovidae)
Habitat: Carpentaria Lake and swamp forest of northern Meganesia.
Picture by Alexey Tatarinov
The Pleistocene saw Australia populated by giant herbivores
of the marsupial kind, now extinct, such as Zygomaturus and Palorchestes; such
animals may have spent some time in water, but could not pass fully to an amphibious
lifestyle due to rearing cubs in a pouch. The Holocene saw these large animals
replaced by introduced ungulates brought by white settlers, among them was the
Asian Buffalo (Bubalis bubalis), an animal with a preference for swampy habitats.
Its descendant in the Neocene has realized what the ancient marsupials could
not, a completely amphibious mammal, analogous to the hippopotamus. This animal
is the Bovipotamus. This animal is relatively small compared to its ancestor;
the male reaches 400 kilograms while the female attains only 250 kilograms.
Its small stature allows it to live in large groups and walk through forested
areas with less difficulty. Its body is bulky and short-legged, with a larger
head in proportion to its body than its ancestors, in this sense it resembles
a pig at first glance more than a bull. The hooves are able to spread apart,
allowing it to walk on swampy ground, and between the hooves there is a web
of skin to aid in swimming. Nostrils, ears and eyes are all positioned on the
top of the head, as with the hippopotamus. Its skin is dark grey and almost
bald with hair only on the tip of the tail and along the neck. The hide is thick
to deter biting insects and to protect against scratching vegetation. Its horns
are broad at the base, forming a helmet like that of a musk-ox, this allows
not only for combat but also to pass through rough vegetation even at a gallop.
The points are small and swept to the side; males have larger horn points, while
females simply possess the "helmet" with small points facing downward.
This animal is vegetarian, feeding on reeds and water plants. It forms large
herds of up to 30, whose feeding prevents the Carpentaria Lake from becoming
choked with vegetation. They spend most of the day in the water, and can dive
to 2-3 meters deep to feed on aquatic vegetation such as the tubers of water-lilies.
They also feed at the surface on water-hyacinth and the leaves of water lilies.
During the night they disperse onto land to feed on reeds, and will sometimes
eat softer vegetation in the swamp forest. During the day they stay in the water
to prevent overheating. They are preyed upon by the Yagil
and the Marsupial Panther
when it is on land, and large aquatic pythons
prey on their young in the lake.
The breeding time occurs in the dry season, when there is enough dry ground
to run about. The males will display by throwing vegetation up with their heads
and horns. When in combat, the males shove one another with their horn-helmets,
head on. The males form leks of several individuals. The female gives birth
to one large calf, which can swim immediately. Calves have light grey skin which
sometimes has lighter patches that disappear with age. This animal has a lifespan
of up to 30 years.
This species of mammals was discovered by Tim Morris, Adelaide, Australia.
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