Great reef builders

 

Tour to Neocene

 

5. Great reef builders

 

 

 

Unfortunately, it is impossible to name “coral” reeves of the Neocene era, growing in Indian ocean. The mass extinction of the species which have finished a Holocene, has mentioned also numerous species of the reef-building corals. On Neocaenic reeves sedentary coelenterates animals are on the subordinated roles. They form small communities in calm lagoons of reeves. The past coral magnificence vanished and did not remain a trace though reeves are rich of life. But the reef is constructed by other alive creatures.
Corals took the special place among animals - due to symbiotic algae in tissues they were producer animals. It is necessary to remind, that overwhelming majority of animals are consuments, that is consumers of available organic substance. So the place of corals in a nature was exclusive. But after extinction of corals it have been divided among various organisms postponing a limestone. In shallow, well illuminated places of a reef which are always covered with water, thickets of the strange green seaweed similar to any alien plants from fantastic film wave. But it is quite alive seaweed which and now can be seen on a reef - Caulerpa and Halimeda. They are covered with a crust of a limestone, representing a delicious dish for crustaceans. Crusts of microscopic pink and olive-brown colored algae alternate with massive colonies of molluscs - main builders of reeves. On surf territories of a reef colonies stone oysters adhered to each other, and in places which even in outflow remain under water expand, colonies of the "blossoming" tridacna settle down. Edges of a pallium of this mollusc come out between shutters of a crooked shell. Pallium is blue - green colored because of set of the seaweed inhabiting tissues of a mollusc. The tridacna lives almost exclusively due to photosynthesis of these microorganisms, therefore it competes to other alive creatures only for the covered place. Stone oysters with their extremely strong shell inhabit places where not every kind of reef creatures can survive - in a zone of strong waves on external edge of a reef. There they have constructed the real barrier fastened, as the cement, by microalgae depositting a limestone. Only the strongest creatures, capable to resist to furious storm, can occupy this place. But here they receive all organic substance which the sea brings, leaving about half of all plancton brought to a coast for all other inhabitants of an internal zone of a reef. Powerful walls of stone oysters serve as the natural breakwater preserving internal zones of a reef from furious impacts of storm waves.
Between a wall of stone oysters and a coast it is stretched more or less wide area occupied with reeves. It is filled by sponges, tubes of sedentary worms and shells of the "blossoming" tridacna. This organisms divide a reef into set of the lagoons divided by barriers from shells and tubes. Free spaces on shallow waters are occupied by a crust of limy seaweed, and in deeper territories and a surf zone – by white limy sand.
Sand in a zone of a surf seems is lifeless, but actually it is manned. The set of digging organisms inhabits it. And the most numerous kind of them are small sandworms. Their food is organic substances, cast a shore. Worms pass oozy sand through intestines and eat rests of plants more accessible now. Earlier reeves was built by strong corals. They easily kept organic substance due to strong skeletons. But now one of main manufacturers of an organic substance on a reef are rather fragile algae. Even weak waves easily break off thallomes of seaweed, and after storm the whole shaft of green, reddish and brown plants decay on sand, gave out a fetidity. But this ones quickly disappear - sandworms sap under them and eat weight of plants, multiplying in great numbers. They breed not only by eggs, but also by simple division into some parts, each of which regenerates to the high-grade worm. It allows them to breed very quickly. And there is an occasion to this.
Sandworm population feeds set of alive creatures. One of them is a sea dragonfly larva. It breathes with the help of gills on a tip of an abdomen, and does not emerge behind air on a surface. The lower lip of a larva, or "mask", is covered with hairs and comes to an end two sharp palps. It allows an insect to dig out small worms of sand. Having pulled out the worm from its refuge, the larva of a dragonfly keeps it by palps and brings to a mouth, using "mask" as a hand. For day the larva can have eaten about ten worms. But also the larva of a dragonfly should be on alert - it too can fall prey for different inhabitants of a reef. In case of danger, having noticed a fish, the larva is capable to be floating with the big speed to the nearest shelter in a reef. Thus it is similar to any small fish. And if it appears on an open territory, it acts the same way as also its catch – it hides in sand, being dug in it for parts of second. Jerk - and a larva is hidden, only little cloud of silts curls where it was dug.
But not always sand is reliable shelter. Sandy shallows in inflow are surveyed by the strange sluggish fish similar to the come to life Chinese dragon. Its mouth is on the end of a tube-like snout, and the body is covered shell plates. The flexible tail is decorated with scalloped skin outgrowths, flutters behind, as if a pendant. It is the sea piggyhorse named so for a manner to search food. If sea horses known to people eat a plancton these species have passed on a benthic forage. Change of a diet has rescued these species from extinction when stocks of plancton organisms at ocean were undermined by nature cataclysms. The sea piggyhorse digs sand the snout, finding sandworms. It soaks up the worm by a tubular snout, and sand is thrown out through branchial apertures. If the larva of a sea dragonfly or the small shrimp comes across, the sea horse pulls it out from sand, "chews" by jaws that catch to kill it, and then re-snatches and soaks up the catch.
Searching food the sea piggyhorse surveys sandy shallow waters of a reef the long snout. But it can be unsafe.
On one sandy bottom the fish notices, that sand has begun to stir. It is a true attribute of presence of sandworms under sand. But, unfortunately, it can be not only them. The sea horse slowly floats above a sandy bottom; the fish turns a head on the sides, trying to find out food organisms. However it is not a lunch table, but it’s a trap. Sand as if blows up: about twenty fishercrabs jump out of it. Dexterously rowing by back leg pair, they are capable to float and change movement direction quickly. All crabs are hungry, and as if on command, they are thrown on a sea piggyhorse. Pincers easily manage shell of a fish, and already all school of crustaceans feasts on remains of fish. The largest ones greedy tear meat by mouth feet, from time to time showing the pincers to neighbours when those approach too close. The young growth, preferring to not enter fight with adults, wanders at some distance, picking up pieces of meat from a table of stronger neighbours. Having sated, adult crabs crawl out and dug in sand. The young growth still any time late on almost completely eaten round backbone of a fish, and then they crawls out too and hides into the sand. Burying in sand, each crab put out on a surface only eyes on stems and a tube of antennas on which water acts in its branchial cavity. In case of danger it buries itself more deeply in sand, and dug out one tries to be rescued by flight and to hide in cracks of a reef.
The sea horse is easy for hunting, but poorly edible catch: it is a plenty of bones and shell plates but not enough meat in the body of this fish. Not all crabs were sated, and almost young growth has remained hungry. And animals prepare for an ambush again. Having dug, the crab starts to move with one of walking legs, simulating movements of the worm in sand. The small fishes who have come on search of easy-catching food, become catch of shell predators.
The huge roundish shadow similar to a shadow of a dirigible balloon, smoothly and slowly slides above a reef. It is one of the largest inhabitants of a reef - the crushing trunkfish has left escape on food search. Its mighty jaws are possible to crack the firmest shell, and the fish is hungry. Trunkfishes live one by one and survey the extensive territory for some days. They eat practically everything, that can prey and crush by powerful jaws.
The splash on a water surface draws attention of the huge fish. By experience the trunkfish knows, that sometimes in water the meal falls from the sky. The winged shadow flies away from the bug who has fallen in water - it is a gullbat hunting on fishes. To the trunkfish it is not dangerous - it is too heavy. Therefore the fish unpunishedly carries off the torn up bug in water and eats it, oblige a bat to search for a new bait. The trunkfish already faced closely with these creatures: in back edge of shell fish carries awful "gift" - a paw of a long time ago decayed bat. Probably, the hungry or inexperienced gullbat has overestimated its might and has attacked trunkfish. Claws of an animal have stuck in an osseous shell of the trunkfish, and it has drowned the unlucky winged fisher.
One bug is only has excited appetite of the giant, and the fish is floating further. The smell of the fresh rests of a fish brings the trunkfish to a sandy glade where the piggyhorse was preyed. The trunkfish sniffs at remains of the sea horse and starts to chew a ridge of a fish. At this time tens eyes observe of it, and then attack follows. Fishercrabs seize a shell of the trunkfish, but it’s all - a crab does not gnaw through a shell of this fish even during half-year. But one young crab bites a gentle skin near an eye and after that the trunkfish has the right protect itself. From a cloaca of a fish the yellowish jet fast dissolving in water is pulled out, and the trunkfish makes a sharp turn on a place. Crabs, as if on a signal, start to recede. But they do not bury themselves in sand, and by all school go to a reef. The trunkfish has used the chemical weapon - a poisonous liquid. And about half dozen of crabs deafened by this “secret weapon”, fall on sand. The trunkfish has turned to the hunter from prey, it devours the former enemies with a crunch.
And crabs move on the next sandy shallow, not suspecting, that one more enemy has noticed them. Crustaceans have no time to bury themselves in sand when above a shallow there are butterfly cuttlerfishes. Quivering spotty fins, these creatures fly above a bottom by a school. If it been the lone cuttlerfish, crabs would attack and eat it. But it is the school of these molluscs, and their stings are extremely dangerous to crabs.
Trying to appear inaccessible, crabs betrayed themselves: burying themselves more deeply, they throw upwards a fount of sand. And it becomes for them fatal: cuttlerfishes notice crabs, and hunting begins. Long trap tentacles snatch out former successful hunters from sand, and the strong sting of a beak makes them simply a meat for a hungry mollusc. Still more some crabs leave life for the sake of life of cuttlerfishes. At some cuttlerfishes on hands sheaves of eggs are visible: they are females bear posterity, remaining thus active. Such strategy proves its value doubly: the posterity is better protected, and females are not killed with a secret of optical glands, and they survive after a hatching of posterity. One of females already carries larvae - two tens of small cuttlerfishes sit, having grasped its feelers. Female has preyed a crab and now divides it among the posterity. Gradually, having felt strength, larvae will swim out. For now they are under reliable protection of the whole school of adult animals.
Cuttlerfishes slowly float above the crushing trunkfish who surveys a reef in searches of food. This fish doesn’t stay too long anywhere to not exhaust resources of a reef, but the fish is compelled to eat small portions almost constantly. And now it has swum up to a colony of the sweepworms more similar to a congestion of factory pipes, sticking up of a body of a reef. At approach of a huge fish worms put color sultans of tentacles and are hidden in tubes. Their weak spot of this animals is that from tubes they will not escape anywhere else: they are sedentary worms. And the trunkfish begins crack one of pipes. Its strong jaws bite off huge pieces from dwelling of the worm. And reaction to it is immediate: from one, another, and then almost simultaneous volley from all other tubes throws out jets of a violet liquid. It is poisonous, therefore the trunkfish at once swims aside and starts to scratch about a shell of the "blossoming" tridacna which instantly hides edges of a pallium under protection of shutters.
On a reef it is favourable to be not only a predator. On Neocaenic reeves the considerable role is played by seaweed, than some fishes have taken advantage. They simply grow them and eat. It is simple to make: don’t let other herbivores in the chosen territory.
The suckerfish acts this way: it drives from the plantation of seaweed not only other herbivores, but also the neighbours. Borders of possession of these fishes are protected better, than frontiers at people. The owner (or nevertheless the owneress? These fishes are hermaphrodites) of the territory vigilantly keeps up borders of a territory from an eminence. Thickets of fantastical seaweed which from time to time have "hair cut" by fish jaws up to a condition of the present English lawn, wave around. If the shrimp or the careless neighbour penetrates on territory as the fish - owner darts off and puts to the infringer strong impact by a strong forehead. If the infringer is the neighbour who is not going to concede, can be fastened fight. Sometimes the scaly planter is compelled to leave the possession and to search for a new place for life. These fishes occupy the eminences, exposed to a draining part of reef during outflow. The fish can survive any time without water. To thicket of their colony settle down on shells of stone oysters or tridacnas in an internal zone of a reef.
It seems, that these fishes are incorrigible egoists. But the common trouble rallies neighbours. A unique case when the fish unpunishedly can break another's borders is struggle against the common enemy. This enemy is sea urchin. Silent prickly gluttons are capable to scrape off up to limestone a plantation of suckerfishes. They are too great, therefore one fish can not manage them. If the sea urchin will penetrate on a plantation, the fish utters an alarm signal: series of short clicks. On this sound all neighbours gather, and the prickly infringer of borders is expelled by the common efforts by almost synchronous impacts of foreheads.
Clicks of ram suckerfishes involve not only their neighbours. The sluggish and bright shark with wide fins and strong jaws too willingly comes on this sound. Fishes do not interest this shark, and anybody will not envy to the sea urchin: jaws of a shark easily crush its shell, despite of needles. It is the shellcracker shark, and echinoderms and molluscs with firm shells are its food. Similarly to the trunkfish, this shark patrols a reef searching the food. Single sharks of these species meet only on short time of pairing, and all rest of the time will spend in the territory, jealously protecting it from colleagues. The young growth of these species has sandy colouring. Small sharks eat worms searching in sand, therefore large shellcracker sharks do not pay attention to them. But when the young growth gets adult colouring, it will come to be careful of neighbours and to win to itself individual territory.
These sharks are, perhaps, one of the most harmless inhabitants, dangerous only for inactive invertebrates. But from the sea on a reef much more furious creations - ocean fishes come to be fed. Schools of pelagic fishes, similarly to packs of wolves, bring a devastation on reeves. Everyone who has not had time to hide or it can not be protected, turn in victims. However and for these pirates the reef can become a trap: in outflow the reef turns to a net of shallow reservoirs with heated water. The contents of oxygen in water falls, and exacting ocean dandies start to choke. They float near surface of water, powerlessly moving with fins. Schools of creatures even more some hours back inducing horror on inhabitants of a reef, turn to easy catch. Fishercrabs become fat before eyes, butterfly cuttlerfishes, not paying attention to crabs, devour helpless fishes, and gullbats at all do not trouble themselves with search of a bait - they snatch out from dense shoals of reef captives two fishes at once - each paw on a fish. But this feast will proceed only before inflow. The wave from ocean carries oxygen and clearing for fast predators of the high sea.
Time imperiously above all worlds of the Earth as the face of a planet varies also. There are no absolutely isolated places on the Earth, everywhere there are changes.
They have touched also island continent which was isolated from around world longer than other continents.

Bestiary

Sandworm (Psammotubifex simplex)
Order: Haplotaxida
Family: Tubificidae


Small (length up to 5 - 6 cm, thickness 2 - 3 mm) annelid worm forming in sand of a reef large colonies. Eats an organic substance contained in sand of a reef. The head end is in a thickness of sand, back is put out outside. On it small bushy gills of red color (in blood of the worm there is a hemoglobin), making respiratory movements are located. In case of danger the worm is involved in sand and quickly dug in more deeply. The hermaphrodite, during outflow after the highest inflow a colony of worms on all reef simultaneously "throw" in a leaving wave sexual products, fertilisation occurs in a thickness of water. The larva covered with ciliums lives in a plancton, it is carried by currents. Later it settles on a bottom and transmutates to the young worm. In intervals between inflows the worm can breed, any way sharing in two, that allows to increase and restore number of a population quickly. Each half of the worm completes the lost parts.

Sweepworm (Tubiserpula trachytuba)
Order: Sabellida
Family: Serpulidae



The sedentary annelid worm forming as shelter a limy tube in length up to 60 - 80 cm. In process of growth the animal gradually increases the top edge of a tube and strengthens walls from within. Outside the tube acquires a layer of the small sea animals postponing a limestone (small actinias, bivalve molluscs), becoming in such a way a part of a reef body. Larvae settle near to adult worms, forming at times close groups ("wood" of tens animals. From a tube look out long feelers of a forward part of the worm, painted in black color (are similar to a brush for chimney cleaning). Worm eats the particles of organic substance sticking to feelers. The part of an organic substance is dissolved in slime and acquired directly through an epithelium. At danger the worm involves feelers in a tube, densely closing it by lime-horn operculum growing on a head. If the enemy tries to break a tube, the worm lets a poisonous violet liquid in water. For neighbours it serves as a chemical signal of danger, and they are promptly hidden, letting out the same liquid which on some time deprives a fish of orientation.
The hermaphrodite species, animals one by one let sperm and only a bit later after that are ready to fertilisation. Spermatozoids settle on feelers of an animal and independently will penetrate on the slime covering a body of the worm, into sexual ways, making internal fertilisation. The larva some time grows in an organism of mother, eating secretions of walls of sexual ways. Later large larvae are "thrown" in water and are carried away by waves.

Stone oyster (Petrostrea robusta)
Order: Mytilida
Family: Ostreidae


The bivalve mollusc attaching to stones and forming on reeves the big congestions. The animal adheres to a stone or the limy basis of a reef by the right shutter, which is very large, goblet-like, with numerous ribs. The left shutter is flat, serves as "cover" for the right shutter. Edges of shutters are wavy, but shutters are closed very densely. The size of a shell is up to 50 cm, height - up to 35 - 40 cm. Eats similarly to the majority of bivalve molluscs by water filtering. Forms huge colonies (up to 100 and more individs in group). Settles on the most surf sites of a reef, tolerates a draining part of reef at outflow. Lives till 100 years and more.

"Blossoming" tridacna (Obliquitridacna florida)
Order: Venerids (Venerida)
Family: Tridacnidae


The huge mollusc forming the big congestions in calm parts of a reef not exposed to a draining. The shell is extended in width, the sizes: 1,8 x 1 m. Edges of a shell are very wavy, the pallium of a mollusc juts out from them. Outgrowths of a pallium are very folded, contain colonies of green and blue - green symbiotic algae. The mollusc foods almost exclusively at their expense, filters an organic substance with the help of complex gills and uses it only for fertilizing of symbiotic algae.

Butterfly cuttlerfish (Papiliosepiola colorata)
Order: Cuttlerfishes (Sepiida)
Family: Sepiidae

Colorization by Ilia

The small cephalopod (length of a body - 15 cm, feelers - 10 cm), the descendant of modern cuttlerfishes (Sepia), living on reeves by the big schools. The body is brightly painted: on a white background there are symmetric figure composed by large black-and-blue oculate spots. Males have big red stain on the ends of trap tentacles. Eyes are very big, sight is sharp. In case of danger colouring easily varies on cryptic. The animal is capable to throw in the enemy ink "bomb".
The predator, eats crabs and shrimps whom kills by a poisonous sting.
The female is remarkable by original care of posterity: it bears eggs on two back pairs of tentacles, holding their combined like "basket" up to a hatching of young growth, and also first time after a hatching. The young growth leaves mother at the age of one week after a hatching, when a yolk sac will resorb. At a bearing of posterity the animal does not cease to eat and can give up to 3 packs during lifetime.

Fishercrab (Velonectes piscatorius)
Order: Decapods (Decapoda)
Family: Portunidae


Small (width of carapace is up to 10 cm) crab, the descendant of swimming crabs (Callinectes). The body is flattish, together with clasped pincers and walking legs gets the streamline form (“a diving saucer”). The back leg pair is flat, it is used for fast and maneuverable swimming. Colouring is sandy - white with grey speckles, a bottom of a body is blue. Lives on sandy parts of a reef by big uneven-age schools (up to 50 - 70 individuals), being dug in sand. Eats fishes whom attacks by school. For attraction of a fish the crustacean is capable to simulate legs of movement of the worm under sand.

Shellcracker Shark (Neorectolobus durophagos)
Order: Orectolobiformes
Family: Orectolobidae



The small species of sharks living on coral reeves. Is the descendant of horned sharks, keeps many features of their appearance: a spike in the beginning of a back fin, a short head and ledges above eyes. A body is high and rather short, fins are wide. Jaws are short and very strong, forward teeth are cutting, back ones - crushing. Length is up to 1 meter, more often smaller. Fishes of this species have very bright contrast colouring: the body of coffee-black color, back fins and a tail are bordered by a wide orange strip, around of eyes there are wide white rings, a stomach is white with small black speckles. Bright contrast colouring testifies to territorial behaviour of fishes: each shark has an individual territory on which outside of a breeding season neighbours are not supposed. Eats basically echinoderms: starfishes and sea urchins, less often eats crustaceans and other prey with firm covers. Lays up to 10 - 15 eggs for a season, protects a place of a laying. Young fishes (length up to 10 cm) are sandy - white, eat spineless invertebrates. First time they live on a territory of mother, later swim out.

Sea piggyhorse (Dracocampus porcinus)
Order: Pipefishes (Syngnathiformes)
Family: Syngnathidae

Picture by Ilia

The large species of sea horses eating worms. It has survived in time of " plancton accident ” due to a feed by benthic organisms. In the length up to 80 cm from which about half falls to a tail. The body is covered with a shell consisted from separate, movably jointed plates. On a head and a trunk there are some numbers of the skinny outgrowths simulating bunches of seaweed (on a head they are especially long). Colouring strongly varies, represents a combination of red - brown and white irregular-shaped spots. The snout is long, flattish on the end; it is adapted to excavation of worms from sand. Floats slowly.
Care of posterity - as at modern species of sea horses: the male bears eggs in a bag on a stomach. Fecundity is up to 200 eggs.

Ram suckerfish (Algotris rubro-album)
Order: Percoid fishes (Perciformes)
Family: Eleotridae



The specialized species of family Eleotridae. Outwardly resembles the goby (Gobio) with a wide-foreheaded head and small eyes. Length of a body is up to 20 cm, colouring is bright: a forward part of a body is bright red with a black forehead, back is white. The mouth has changed: from prehensile it has turned to scraping one. Abdominal fins have formed two suckers that allows a fish to keep in a zone of strong current. The fish lives in the certain territory which protects from other representatives of the species and from herbivorous invertebrates (molluscs and sea urchins) which rejects by impacts of a forehead. Eats green and brown algae, makes original "plantations" on more or less horizontal plates of a reef (including shutters of stone oysters). In absence of herbivores the territory chosen by ram suckerfish quickly grows with seaweed which are eaten by the small fish. In outflow it is hidden in cracks between molluscs or in others refuges.
The fish is hermaphrodite, it is capable to change a sex during a season of spawning. Pair of fishes spawns on border of fodder territories, the fish who has laid it looks after clutch. Fries the first 7 - 9 days live in a plancton on a reef, later pass to a bottom and live on borders of adult fishes territories.

Crushing trunkfish (Titanostracion destructor)
Order: Tobies (Tetraodontiformes)
Family: Ostraciidae

Very large species of trunkfishes (Ostraciontidae) living on reeves. Body length of adult fish is up to 90 - 100 cm, weight up to 40 - 50 kg. This fish is almost completely covered with a shell giving to a body the angular shape close to cubic. Above eyes there are straight hornets up to 10 cm long. Only the short tail stalk is free of shell. Colouring is very bright and varies depending on gender and age: males are brick-red with white ring-like spots, females are entirely black (including fins) with a white edge on all fins; larvae of both sexes are white-coloured with green irregular-shaped spots. Colouring changes on adult type only after the first year of life. Fishes are poisonous, in case of danger emit out in water strong poison (similarly to modern representatives of family). This fishes swim very slowly.
This species eats invertebrates with firm covers, mainly molluscs which grinds entirely by strong jaws. A considerable part of sand on reeves is the result of work of crushing trunkfishes. Fishes do not adhere to the certain territory, but outside of spawning season they avoid meetings with each other.

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