Tour to Neocene
During the second half of Cenozoic era Antarctica has turned
to icy continent almost lack any terrestrial life. Only in some places there
were “oases” – land areas lack of ice. In such places mosses and lichens and
in some places even grasses grew. From among animals in such places there were
only tiny insects. In Neocene, when the climate began warmer, the surface of
continent began releasing from an ice shield. On the ground thickets of mosses
and lichens gradually appeared, and there insects settled – the descendants
of ones have got to the continent with winds from Africa and South America.
In addition to them on deserted coast of the continent birds had began to fly
and to bring even more seeds of grasses on their paws and feathers. Edges of
the continent in Neocene became free from ice, and now the wide grassy steppe
with some areas of dense cushion bushes was stretched there. Only the borders
of glaciers still have the rests of initial flora of Antarctica – a belt of
In winter there is still cold in Antarctica, and there is a polar night. But in the summer the sun shines all day and night, and for some weeks a year the weather happens rather hot.
In the center of Antarctica glaciers have not thawn yet, and many rivers originate at the Central Antarctic Glacier. In summer ice begins thawing gradually, and water accumulating on the surface of a glacier in extensive lakes searches for a way out. Usually any edge of a glacier does not maintain its pressure, and water washes a deep gully, flowing down on slopes of glacier.
At the way of thawed snow from a glacier the zone of peat moss bogs is stretched. Sphagnum moss has a unique moisture capacity, and in spring bogs literally inflate like sponge, and then gradually give the stored water to numerous streams. Flowing through peat bogs, water is additionally cleared of dust and suspension and turns more acidic.
Sphagnum bogs of Antarctica represent the residence of the most ancient settlers of the continent in postglacial epoch. Here there is an original microclimate, an echo of the past epoch: close glaciers freeze ground, and from them the cold wind frequently blows. Therefore local inhabitants live either in the slowed down rate, or in maximal degree use short serene days. Since early spring, when the sun warms enough, some moss cushions show the appreciable movement inside them. There thick grubs with translucent body covers – posterity of the large moss leaf beetle – wriggle and eat leaflets of sphagnum. They have fine appetite, and after their feeding on the surface of moss appreciable bald patches arise. Grubs of moss leaf beetle hide among moss plants, staying between their stalks. Only the head of grub, gnawing obstinately fluffy heads of moss, is visible from outside. When above bogs any casual bird flies by, grubs, as if on command, hide deeply in moss. It is their usual reaction to large and quickly moving objects. They do not distinguish colors and small details with their small eyes, and can see contours of the objects only. The main task of these grubs is to eat well. Grubs of early clutches may turn to adult beetles this summer.
In addition to moss leaf beetles at the bogs many other insects feed. But some of them will be noticed hardly even by sharp-sighted bird. Myriads of tiniest springtail insects skip on surface of moss, and even of water. They live in the world where the gravity is not of great importance, but other forces are felt much keener, than in a macrocosm. The surface tension film supports them, as if elastic trampoline - they are too easy to break through it. Springtails are among native inhabitants of Antarctica which have survived in Cenozoic glaciation of the continent. Some species live even on the surface of glacier where they feed on algae developing on snow and in pools of melt water, and also on insects blown here by wind.
Bogs seem stagnant only at first sight. Actually water is constantly freshened, especially in the summer, when the Central Antarctic Glacier melts. Water from bogs around gradually filters and gathers to numerous streams murmuring at the meadows of Antarctica and merging gradually to larger rivers.
Antarctic streams are remarkable in cold and clean water. This is a favorable place for breeding of smaller Diptera species. Larvae of diverse midges stick like a live carpet on all places suitable for their life in the slightest degree: the surface of stones and plants. Larvae attach to stones using the viscous liquid stiffening like glue. Having attached in suitable place, larva stretches its antennae in stream of water to catch various edible things. Plumose antennae work as a sieve, catch the vegetative rests and the protozoans carried by water. From time to time they are turned to the larva’s mouth and it eats the caught animals. In absence of the majority of enemies, first of all of fresh-water fishes, midges and mosquitoes of Antarctica prosper. But dipterans do not stand at the top of food pyramid: they nevertheless have enemies even in this isolated world.
From under flat pebble even flatter live being appears. This strange creature is kept in strong current, seizing by legs in the smallest asperities of the stone. To fix additionally in current the suckers developed on legs help it. And moreover the body shape also represents a sample of technical perfection: current literally presses strange creature to the bottom instead of breaking it out and carrying away. But all the same the small monster is very cautious: it moves its legs one by one, and five legs from six always seize a stone. Frightening head with large spherical eyes and the triangles of underdeveloped wings stretched along its back clearly show an origin of this creature: it is a nymph of dragonfly – one of numerous species of these insects inhabiting Antarctica of Neocene epoch. Adult individuals of this species swoop above the stream, sparkling with blue metallic shining abdomens. The abdomen shape of an adult dragonfly almost does not change, hence the name of this insect: flattened stream dragonfly. Midge larvae stand at the bottom level of food pyramid in stream: they serve as food for this nymph. Flattened stream dragonfly nymph scrapes them off with its wide mask (lower lip), as if by shovel. It as if grazes on the underwater meadow, tearing off from stones larvae of midges, flies and mosquitoes which can’t or simply have not time to escape from it. But sometimes it is necessary for the nymph of flattened stream dragonfly itself to show quickness and care. From time to time stream is visited by larger predators, local birds, for which flattened stream dragonfly nymph is simply an easy snack.
Falcon grackle, one of zoophagous birds of Antarctica, frequently flies to the stream in searches of food: it is possible to find a lot of meal here if to attempt. The bird knows how to get midge larvae. It overturns pebbles and pulls them out from water, stacking one on another, and then quietly pecks off midge larvae attached to it, which can’t escape in flight. From time to time the feathery predator sneezes, when water gets to its nostrils while it takes the next pebble from water. But midge larvae represent no more than snack, and the bird searches for more essential prey. Nymph of flattened stream dragonfly will fit for dinner to falcon grackle quite good, but it is more difficult to catch it. While grackle is rummaging somewhere aside, nymph eats, not paying attention to it. But at first signs of danger, when the bird has stepped in its side, nymph had promptly squeezed deep between stones. With its sharp-sighted eyes the predatory bird notices the movement among stones and begins the pursuit of dragonfly nymph. It overturns small stones, trying to find nymph, but it is simply dug in gravel. If the falcon grackle would be more persevering, it would catch the nymph. But the bird has a great disadvantage: water gets to its nostrils, and the bird sneezes for a long time. The effect of suddenness is lost, hunting has not gone right obviously, and falcon freckle flies out soon. When the situation had quieted down, midge larvae turned to lumps began to straighten antennae on the sly, and a bit later gravel at the stream bottom has begun to move, and from its shelter dragonfly nymph creeps out. Having convinced that everything is quiet around, it has continued scraping stones.
Falcon grackle is more an “amateur fisher” – it incidentally searches for food in rivers and only diversifies its menu with insects. But the bird which has mastered underwater feeding is found in bogs of Antarctica. Necktied mousebird, tiny flightless passerine bird, accurately moves down under water, clinging by claws against the stems. Before diving it carefully greases plumage with secretions of preen gland to prevent getting wet. Therefore when this bird appears under water, its plumage becomes silvery from the thinnest layer of air which is kept on its surface. Nostrils of mousebird at diving are closed by small leathery lids, and the bird feels like perfectly under water. Having gone down to the stream bottom, it hasty rummages around stones, pecking off midge larvae. Feeling that the stock of air comes to an end, mousebird simply unclenches its toes, emerging on surface of water, as if a cork. Due to greasing the plumage appears dry, and the bird does not soak through and does not feel cold. Within the year it continues hunting under water until streams will cover with ice.
Having caught its breath, necktied mousebird dives once again. And at once it notices under water the nymph of flattened stream dragonfly, which unperturbably scrapes midge larvae from stones. This prey costs the works on its capture, and the tiny bird rushed on it like a cat on the mouse. Having torn off the nymph from stones, mousebird emerges on surface of water, leaves from the stream and begins banging the dragonfly nymph furiously against small stone. When the movements of insect had stopped, mousebird had pressed it by paw and began tearing off pieces of it with powerful beak, greedy swallowing them. In some minutes from dragonfly nymph only frightening head and the rests of legs remain. Having finished the meal, the bird has disappeared in thickets.
Antarctic streams gradually merge to small rivulets, and they are united to wide rivers meandering on plain. For freshwater fishes sea open spaces represent as absolute obstacle, as the highest mountain ridges or waterless desert, therefore the rivers of Antarctica completely lack of freshwater fishes. Only occasionally marine fishes come to rivers mouths to get rid of parasites irritating them. But they also do not remain here for a long time. But in fresh waters of this continent aquatic insects have found the new homeland. These creatures had easily overcome hundreds of kilometers above the ocean, and colonized the continent. Dragonflies have especially succeeded in development of Antarctica.
In thickness of water numerous long-bodied creatures swim. At first sight it seems that in water shoals of fry of various fishes teem. But at closer look it appears, that each of such “fishes” has short antennae and six legs which nestle against its sides during the swimming. These are nymphs of one of the most surprising insects of Antarctica, of stripe-tailed insectfish. Their gills growing on the tip of abdomen are colored black and white, helping these nymphs to distinguish each other at the great distance and to unite to schools for protection against enemies. These creatures behave like fishes in many respects: they gather in many thousands schools and swim together, coordinating their movements. But here it is not only external similarity: eating tiny plankton worms and crustaceans, they occupy an ecological niche of small fishes. Diverse species of insectfishes substitute various fishes that became possible because of absence of competition to fishes in Antarctica.
But fishes are different, and there are predators among them. And among their Antarctic six-legged analogues also there are the creatures which are not making a concession in ferocity to fishes of other continents (certainly, with the correction for their size).
Striped greenish nymph about 10 cm long traps small insectfish nymphs under leaves of cane floating on surface of river backwater. It is a nymph of the species related to stripe-tailed insectfishes – of voracious insectfish. Waiting for an opportunity to attack small animals, it hangs for hours under the stalk of floating plant, having hooked for it with one leg. Huge spherical eyes look for any small creatures scurrying in water. Nymph does not pay attention to the tiniest worms and small mosquito larvae which swim fast beside it and even hit on the hidden nymph. But it waits for more essential prey.
And after any time its expectation appear justified: in thickness of water small school of little insectfish larvae swims, looking like fry of any fishes. It is a favourite prey of monstrous nymph. Striate nymph, like a river perch, makes a prompt rush. Having stretched the gills growing on its abdomen tip like a tail fin, it swims promptly, bending its body like a fish. The rush is short, but it brings quite good result: striate nymph catches up the school of small insectfishes. Having overtaken with escaping nymphs of stripe-tailed insectfish, the predator opens long narrow mask, and puts with it an exact short impact to one of pursued nymphs. Palps pressed to each other easily punch covers of the nymph and it perishes, being stubbed on the tip of predator’s mask. Having taken its prey with mandibles, nymph of voracious insectfish returns to its shelter, wriggling in water lazily. Having clung to floating stalk, it begins devouring of caught smaller nymph, from which only legs and piece of completely eaten out abdomen remain only.
Somewhere nearby under floating leaves of plants other nymphs of the same species hide. They prefer to keep at the distance from their congeners: it is not known who you would be after fight with them – the winner or its prize.
Not all nymphs of Antarctic dragonflies are furious predators. Swimming in backwaters, stripe-tailed insectfish nymphs frequently meet unusual creatures soaring lazily in thickness of water. These creatures are also damselfly nymphs, but the way of their feeding is unusual. They do not hunt for their relatives, but scoop various aquatic critters with their masks covered with bristles: rotifers and other worms, small mosquito larvae and large infusorians. These are nymphs of “queen of hearts”, one of the brightest and the most beautiful damselflies of this continent. They soar in thickness of water, having stretched in sides their long legs covered with hairs. Small nymphs of insectfish instinctively bypass them, keeping the safe distance, though these creatures are not dangerous to them. They do not pay attention to small insectfish nymphs, eating the smallest fraction of plankton. In quiet water of river bays and oxbows where algae develop plentifully and water teems with tiny plankton organisms, such nymphs live in dozens. Despite of the calmness, such nymph can swim very quickly in case of danger.
The world of dragonfly and damselfly nymphs inhabiting any reservoir is the world of carnivorous creatures. To eat another one or to become eaten – it is a usual business for these insects. And in this severe rule the contribution is brought by creatures from another world, by local birds.
Intrusion into the world of dragonfly nymphs always occurs from above and passes in almost the same way. When the school of insectfish nymphs appears too close to the surface of water, it draws attention of small long-winged bird with deeply forked tail. It is not an Antarctic swallow-looker, an inhabitant of meadows: the bird has white color with black “cap”, and instead of short rostel is armed with rather impressive bill. It is a halcyon tern, the usual summer inhabitant of rivers of Antarctica.
Having noticed a school of stripe-tailed insectfish nymphs, it begins hunting. Having cut water surface by lower jaw, this bird snatches out one nymph from school, soars up, makes a turn and skims over water surface again. Its relatives fly nearby. Having noticed that their congener stays for too long time at the same place, they also decide to try their luck there. After some seconds above backwater small, but noisy flock of halcyon terns is formed. They gradually drive school of insectfish nymphs to riverbank and arrange hazardous hunting for them. But nymphs are not going to surrender to be eaten by birds: their school scatters and nymphs try to leave to the bottom and to hide in thickets of underwater plants. But even here they are unable to find rest: halcyon tern dives perfectly, and some birds immediately direct after escaping stripe-tailed insectfish nymphs. Though why do they need to chase small and resourceful prey, when there is something more essential near them? Large nymph of voracious insectfish was disturbed by dived birds, and now searches for rescue, trying to swim away. But it would be better for it to nestle against floating plants, creeping inside deeper: halcyon terns swim faster than it can, and the destiny of a predator is solved – one of birds eats this nymph.
When hunting of halcyon terns comes to end, dragonfly and damselfly nymphs may continue their habitual life. They live in water till one or two years for flashing their bright colors for some weeks or only some days in the summer, flying above a native reservoir and moving their iridescent wings. And for the sake of this holiday of colors every nymph reached the proper age should pass the transformation.
Insectfish nymphs gather to schools of about the same age and the size that allows them not to be afraid of their own larger congeners. Adult insectfish nymphs, having reached the maximum size, begin preparing to metamorphosis. Shoals of many thousands of them swim up to coastal reeds, and nymphs as if recollect that they have legs. Not paying attention against each other, they creep out on plants. Before this moment they used legs, perhaps, only to leave an egg shell and to live for few days in aquatic moss thickets. Nymphs creep, clumsily moving their legs and trying to climb upper. Having chosen suitable place according the signs known to them only, insectfish nymphs begin moulting quickly. At this moment they are absolutely motionless and defenseless against numerous predators. They are safe from dragonflies of other species, because dragonflies catch other insects mostly in flight, not paying attention to ones perching on leaves. But birds have more flexible behaviour, and they study easily. Halcyon tern involved with an abundance of meal, which as if is asked for getting into the beak, hovers in air and catches these nymphs one by one. But all the same there is greater number of insectfish nymphs, than these birds can eat, and the significant part of them is hidden in thick of canes where long-winged bird can’t fly. Therefore terns do not succeed to put significant damage to moulting insectfish nymphs. Besides under water there is immeasurably larger number of new nymphs not ready to a metamorphosis yet than has got out on plants this day. The flight of insectfishes is dragged on almost whole summer, and each time metamorphosis would be undergone only by small part of the total population of these insects.
For some time insectfish nymphs stay motionless, and only pulsing movements of their abdomens give out the signs of life. But gradually attributes of the future changes become distinct. At first thoracal segments of nymph crack on its back with longitudinal seam. Then from seam wet and shiny body of the future dragonfly appears. Abdomen extends and, as if a spring, pushes young dragonfly out from exuvia which became too close to it. The young dragonfly at first sticks out from exuvia, keeping in it with abdomen tip, and then is bent and clings against the stem by legs. The wings, at first wrinkled and soft, begin smooth out, then harden and soon the damselfly is ready to flight. Windflaws blow from reeds the handfuls of empty exuviae, gathering them in small heaps floating on surfaces of lakes and river backwaters.
Insectfish imagoes migrate to upper courses of rivers where midges and mosquitoes breed plentifully. Mayflies and caddisflies have not reach Antarctica – ocean passages are too wide for these insects living for very short time as flying stage. Therefore at this continent insectfishes replace them. These numerous insects gather in numerous swarms and hover above water. Their winged adult life is very short; therefore they at once arrange courtship flights and form breeding pairs. Impregnated females drop eggs above thickets of water plants like rain. Many eggs will be lost, but ones that will survive are quite enough for reproduction of the species.
Life of adult insectfishes even without additional troubles is short, but many of them perish from attacks of halcyon terns. When swarms of gracile insectfish imagoes hover in an endless round dance, halcyon terns sweep through them, catching two or even three insects at once. It happens even, that seized females continue scattering their eggs until the bird swallows them. Lots of eggs of insectfishes will be carried away by streams to the rivers, but the most part of them will stall in aquatic moss. Minute nymphs burst from eggs; they eat various microscopic low-life and hide among stalks of aquatic moss. With aging they begin spending more time in swimming, and then they are gradually carried by the current to the main channels of the rivers. Here in rather quiet places they form shoals, feed and grow to return in once to upper courses of the rivers where their life began, but using their own wings.
Through swarms of insectfish imagoes adult flattened stream dragonfly flies by, sparkling its blue abdomen. A long time ago, the last year, it had been a nymph and, maybe, hunted these particular insectfishes until they had swum away to the river. But now it is safe for insectfish imagoes though their swarm gives way respectfully to this shining bright insect. Adult flattened stream dragonfly eats small insects – it “trawls” midges by legs covered with hairs and put together like a basket.
Bright colouring of flattened stream dragonflies helps them to distinguish each other at a great distance. In visible light male and female of this species look absolutely equally. But insects distinguish ultra-violet light, and in this light the basic distinctions between male and female become clearly seen. Promptly flying above reeds, males of flattened dragonfly notice females at which abdomens reflect ultra-violet light, forming cross-striped pattern. Having noticed the female, males rush to it from all directions and begin hovering near it, trying to perch on its abdomen for pairing. Courtship games of this species represent the true race which looks very impressively because of flashes of blue color in rays of Antarctic sun. After pairing female finds suitable place for eggs: thickets of aquatic moss, which strands wave in water. The moss forms a dense texture of stalks on which surface spore-bearing capsules stick out. Having chosen suitable place, the insect puts its abdomen into the mat and lays eggs. Nymphs will spend first period of life in moss, and then would creep away to begin the life of solitary hunters.
In spite of the fact that Antarctica is still located at the pole, and in the center of the continent the huge glacier is not thawing, summer at the edges of the continent happens to be rather hot. Polar day began, and the sun at night hours has only “struck" horizon with the bottom edge of disk though at this time weather is little bit cooler. “Night” is not a time for insects: in cool air their activity is reduced, and they simply have a rest. Flattened stream dragonflies at this time hang motionlessly on stalks of reed and sedge. It is too cold to them to fly now. When the sun begins its rise above horizon, and its rays hit dragonflies hanging on leaves, insects turn backs to the sun. Their thoraxes are colored black not without reason – such colouring allows to warm up flight muscles faster, and the insect can take off. But someone has had time to be warmed up much earlier …
From thickets the shining dark blue lightning surrounded with black aura darts off and forces down in air one of flattened stream dragonflies. The creature interrupted the life of this dragonfly is also a dragonfly, but of another species, that is much larger and aggressive. Having finished in air with its prey, it throws the rests in water, makes a turn in air and perches on tall inflorescence of sedge. The feature of this insect – black, as if smoked translucent wings, is evident at once. This insect is equitably named as “black emperor” – it is the true tyrant of local insects, and at times not only of them.
Due to the black wings working as a heating element “black emperor” was warmed up earlier, than flattened stream dragonflies, and has skilfully taken advantage of it. This dragonfly species does not hunt any kind of small fry like mosquitoes or midges – it is an expert in “big game” in scale of the world of insects. From time to time “black emperors” rush through swarms of smaller Antarctic dragonflies, catching them and devouring hurriedly. These ones represent some kind of “micro-falcons” in ecosystem of Antarctic rivers.
“Black emperor” is an insect which at times challenges even to birds. It has keen sense of smell, and sometimes these dragonflies involved with a smell of blood gather on prey of falcon grackles. Their attacks are so resolute, that the predatory bird, being hundreds times heavier, recedes and enables dragonflies to use its prey.
Imagoes of voracious insectfish fly above the river. They flash their bright colors, being as beautiful, as butterflies. This species is one of the brightest insects of Antarctica, one of ornaments of riverbanks. Sparkling bright green bodies, these dragonflies announce with their appearing: the warmest days of summer have come. Only till two or three weeks they fly above the rivers, forming pairs and laying hundreds of eggs. Their adult life is so short not only because they love heat: the matter is that adult voracious insectfish eats of nothing and lives only due to the stocks of nutrients accumulated at the nymph stage. Therefore courtship flights at this species begin right after their wings stretch and insects fly up for the first time. Males search for females and arrange joint flights, sparkling green bands on their wings. Usually the swarm is quickly separating to pairs, and for some time male flies, being coupled with female. After pairing male quickly perishes, and female begins egg laying. For this purpose it perches on plant stalk and puts its abdomen into the water. In leaf axil of cane it lays a lump of slimy eggs containing about ten ones. After that it flies up, moves to certain distance along the riverbank and repeats these actions. Portions of eggs are scattered along the riverbank intentionally to lower the competition between growing up nymphs of the same mother. One more attractive place for egg laying is thicket of marsh plants floating on the surface of certain backwater. Here the competition is less, and a place is more favourable: right after hatching the nymph appears “at home”. But such place is very “expensive” – females of voracious insectfishes do not tolerate competitors, and furiously rush to the competitors decided to lay eggs beside. Attacking the competitor, voracious insectfish female literally “rams” it by head, driving it away from the chosen place. However, it is enough to wait a little, while dominant female will fly out, and it is possible to lay eggs at the same place, but having fought with other interested ones. Theoretically all dragonflies wishing it can lay eggs in “prestigious” place… Or not all can. Some dragonflies perch on floating plants at the safe distance from each other to lay eggs. They sparkle in sunlight with their bodies, and they are noticed by hungry “black emperor”. Like a kite, black-winged dragonfly rushes to insectfish imagoes. They fly away in all sides, and the prompt chase begins. Wings of voracious insectfish imagoes sparkle in sunlight, and one of them is followed by “black emperor”. It is stronger than insectfish imago, which life resources are limited, and the result of chase is in fact predetermined from the very beginning. It is not clear only, which insectfish would be chosen as a prey by this one. Black-winged predator overtakes its prey and seizes its abdomen. For some seconds both dragonflies somersault in air, and then the bitten off head of insectfish imago falls to the grass, and “black emperor” tears its body in flight.
“Black emperor” ends the food chain of the world of insects not only above, but also under water. “Black emperor” nymph, the creature of frightening appearance, corresponding in size to adult dragonfly, waits for prey, having dug in silt. It creeps hardly, but nevertheless it can prey the fastest nymph of any insectfish due to the way of movement inherited from ancestors. While in sight of “black emperor” nymph there is no suitable prey, it tries not to give out its presence. Only occasionally the rests of plants, under which it was dug at the bottom, move slightly.
It is not necessary to wait for a long time for a proper moment for attack: numerous shoal of stripe-tailed insectfish nymphs swims past, moving with black-and-white gills growing on tips of their abdomens. When they swim up too close to hidden “black emperor” nymph, the predator attacks them. Its abdomen is sharply contracted, throwing out from rectum jet of water, and “black emperor” nymph, having pressed its legs against the body, darts off from its shelter and runs into the shoal of insectfishes. It misses a tiny bit only: palps close not on abdomen of insectfish nymph, but on one of its gills which breaks away on the spot. Prey escapes, being almost safe: certainly, after loss of one caudal gill it will swim slower a little bit, but in general it is a norm of life for insectfishes. At the majority of shoal members gills are injured, and at some there are even two their petals torn off.
“Black emperor” nymph is dug in silt again, muddling it by “shots” of water from its rectum. When at the bottom small pit is formed, nymph creeps into it and freezes. Silt and rotten leaves, sedimenting on the bottom, mask the nymph and it is ready to attack again.
From turbid water even more tempting prey appears – nymph of voracious insectfish. The large striate creature swims at a great distance from hidden “black emperor” nymph, but it looks very appetizing, and the predator attacks it from afar resolutely. Nymph of voracious insectfish is a worthy opponent, and the most important act of attack is to neutralize immediately its killing harpoon mask or to seize this nymph in way preventing it to use its weapon. Having attacked from the back, “black emperor” nymph grasps insectfish nymph from above, and literally crushes prey’s thoracal segments by strong palps of its mask. It begins devouring of voracious insectfish nymph even on having waited while its spasms will finish.
“Queen of hearts” nymphs swim in water thickness far from the coast: in this way these phlegmatic creatures avoid attacks of “black emperor” nymphs. But sooner or later they should make a step across edge of water and turn to adult insects. For this important mission “queen of hearts” nymphs swim up to the coast and get into the thickness of coastal vegetation to have metamorphosis in secluded place. Having got out from water, they creep clumsily on legs poorly adapted to it. Getting on plants, they creep on wide leaves and keep under them, having hooked by claws against leaf edges. So they are less appreciable from air at the most vulnerable moment of life. Metamorphosis at these dragonflies is accompanied not only with reorganization of anatomy and physiology of an animal. Even their biochemistry is modified at this time – in their bodies active synthesis of poisonous substances begins. To the moment when wings of young “queen of hearts” stretch and harden, the insect becomes completely inedible. “Queens of hearts” fly up one by one from reeds, and join an endless round dance of their congeners. These dragonflies are colored bright red-brown and look very attractively. One-year-old halcyon tern, which had never seen such colouring at dragonflies, rushes to the swarm of dragonflies and chases one of them. “Queens of hearts” fly not so quickly, and in some seconds the bright dragonfly already wriggles in tern’s beak. With prey in its beak the bird perches on stalk of cane and begins to finish with an insect. With several impacts against the stalk it stuns dragonfly and then tears off its wings. Having finished with it, tern swallows the dragonfly, and… after few seconds begins coughing hoarsely, as if has choked with something. A spasm of muscles of throat follows – and the tormented body of dragonfly is belched with disgust and is fallen in water. Chemical protection has worked, and the bird will remember for a long time that bright color not always means good taste.
Having flied below, halcyon tern drinks water greedy for a long time. When burning in its throat has abated a little, it has flied up above canes. Fast beside it the swarm of bright “queens of hearts” hovers, but the bird even did not want to look at them, though in nest its hungry chicks waited for its return, and the tern itself was hungry.
According the time there is an early morning, but it is imperceptible in Antarctica in summer: there is a polar day, and it is light and warm all day and night. “Black emperor” nymph reached its maximum size gets out on reedmace stalk and hides from undesirable witnesses. Its “crowning” begins: exuvia on its back cracks, and nymph of frightening appearance undergoes metamorphosis, turning to adult insect. Having left its exuvia becoming too close-fitting, young “black emperor” does not make at all the majestic impression that is necessary to a predator of such rank. But about one hour passes, and its wrinkled wings stretch and harden. The insect moves them, as if tries its force, and prepares for the very first flight in its life. Wings work with dry papery crash more and more, and at last the insect comes off stalk and flies up. Having succeeded in underwater hunt, “black emperor” tries itself in aerial hunting now. The first possible prey it meets represents imagoes of stripe-tailed insectfishes – graceful, but very fast creatures. The swarm of these thin damselflies colored black with white cross strips hovers above small rivulet which coastal shallows are overgrown with aquatic moss. The first approach of “black emperor” appears unsuccessful: it had been noticed by one insectfish imago, and its rush aside thickets appeared an alarm signal for other insects. The second attempt is also doomed for failure: hunting is broken by halcyon tern. Having cut into insect swarm, it has grasped two insectfish imagoes at once by long beak and has vanished. But “black emperor” has one stealth in a stock: this insect hunts from an ambush. Having landed on cane stalk imperceptibly, black-winged dragonfly waits while thin insectfish imagoes will lose vigilance and will engage in their affairs again. Expectation of the predator had been crowned with success: from the third attempt “black emperor” rushes through the swarm of insectfish damselflies and succeeds to catch a delicate insect. Having landed on cane umbel, the huge dragonfly eats prey – the first for the adult air hunter.
“Black emperor” is the ruler of an empire of insects, but it is not an absolute monarch in ecosystem of rivers of Antarctica. Here there are creatures which it is afraid of fairly – these are halcyon terns. Quick birds are perfectly equipped for catching of such large and dangerous insects, and swallow-lookers, which catch tiny edible critters above meadows of Antarctica, are not their equals. Halcyon tern with its powerful beak easily catches adult dragonflies of any species and can finish freely with “black emperor”. “Black emperor” has bad luck to be not protected from birds by poison like “queens of hearts” are, and therefore it is compelled to hope only for its speed and acrobatic tricks.
Halcyon tern notices “black emperor” flying across the river. Bird has sharp sight and not less sharp beak, and “black emperor” has much more pleasant taste than “queens of hearts” flying fast beside. And tern rushes to chase for a large dragonfly. Two darts of lightning – black and white – sweep above reeds, making inconceivable loops in air. Sometimes black-winged dragonfly managed to escape the bird, but once the bird’s beak has clicked not vainly.
Burdened with the caught dragonfly, halcyon tern returns to its nest. These birds build rather friable nests of grass in reeds. In the nest two chicks are waiting for this tern. Chicks of this species hatch from eggs already in down and with opened eyes, but all the same they spend a lot of time in nest before they will become fully fledged and will be ready to adult life. At these chicks feathers on breast and wings have already started to appear, but there are also the parts of body covered with the rests of down, because of what young terns look tattered. They seem large-headed while have not become covered by feathers completely yet. Waiting for parents, young birds perch on the edge of nest, preening from time to time and driving away importunate mosquitoes and midges. When one of parents brings food, chicks meet it noisily, wishing to receive the whole portion individually. Having perched on the edge of nest, adult halcyon tern presses dead body of “black emperor” by paw, tears it by beak in two, and feeds chicks by turns. One of them has rather easily coped with its portion – it has got soft abdomen of the insect. But the second one is compelled to choke, swallowing wings which are almost equal in length to its height. But it is helped very much by greed of its sibling: having noticed that near it something large is eaten, it simply breaks off wings of dragonfly one by one while convinced that they are absolutely inedible.
The whole riverbank is divided by halcyon terns into small nesting areas. If the neighbour flies to another’s territory, nest owners drive it away, arranging at times improvised fight in air. But such casual incident may repeat many times at different sites of the river. At times the lawful owner of territory, expelling a stranger, appears on its site itself, and roles are interchanged quite opposite. Such incidents are absolutely safe, and at times involuntarily help birds to remove the accumulated aggression. But they are not comparable with real threat of local predatory birds. In Antarctica the main feathery predator of smaller size is falcon grackle, the representative of passerine birds.
Falcon grackle, the magnificent male with bright yellow “glasses”, flies above canes, looking for easy prey. It searches for nests of halcyon terns in which there are chicks not able to fly yet. But it seems today feathery robber will have no luck to diversify its menu with such prey – its appearing serves for terns as powerful stimulus to uniting. Under the threat of the common danger these birds as if forget insignificant territorial claims and unite to the flock. The collectivism gives boldness to them, and fragile-looking birds attack predator. They try to strike its head by wings and beaks, pull its tail and pull out feathers from its back. Clicking its beak, falcon grackle tries to assume an offensive posture, but halcyon terns are much quicker than it is, and predator succeeds only to pull out a single feather from tail of one of them. In addition to infighting terns apply weapon of “distant action”, rather safe to themselves, but very effective against an aggressor: they fly above falcon grackle, bombarding it with their sticky feces. The predator is powerless against such weapon, and after several “volleys” it flies out disgracefully. And terns turn back to sole owners of small nesting sites, and begin living with their trivial problems again.
Having departed to safe distance from halcyon tern colony, falcon grackle begins shaking off unpleasant “gifts” of these birds from its feathers. It literally wallows in grass, and then runs to the river, and begins scratching and splashing violently in shallow water.
It is necessary to search for the largest birds of Antarctica not at the meadows of continent, but at sea coast. Their trumpet voices are audible hundreds of meters far from the coast. These birds may not hide their presence – at the continent there are no predators dangerous to them.
On sloping coast the noisy colony of large birds – thick-billed penguigulls – spread. They differ from their relatives from subantarctic islands in the impressive size (up to one meter high), more powerful constitution and deep white beak looking like wide blade of knife. At adult birds edges of beak have bright red color, and they drive young birds having unicolorous white beaks as hard as they can. The colony lives its habitual life: birds move to the ocean for food, and juveniles meet their parents with loud calls, demanding for food at them. Sometimes hungry, but strong juveniles take food away at full coevals, and then the fight begins at the coast. Parents do not separate juveniles, but just drive each other away from the nesting territories. In other words, there is a habitual vanity in their colony.
Scavengers can always find profit for themselves in the colony of these birds. Usually the part of juveniles perishes from underfeeding or illnesses, and in colony it is always possible to find some dead chicks. Falcon grackles visit from time to time colonies of thick-billed penguigulls, but they not always succeed to profit with carrion: adult birds are rather aggressive. They do not have attachment to the lost relatives, as, for example, at elephants or apes. They drive predators away only instinctively, seeing in them danger to posterity. But other scavengers easily use a gratuitous entertainment. “Black emperors” fly in the colony of penguigulls, being guided by smell of carrion. Having felt the dead juvenile on which back some wounds from beaks of adult birds gape, they move to its body. Dragonflies are fed on dead juvenile, flying up from time to time when adult penguigulls hobble past. Adult penguigulls are too heavy for hunting for dragonflies and can’t catch them or drive away from carrion. But nevertheless dragonflies do not lose care, flying up when any penguigull hobbles past, wagging clumsily.
From time to time from the ocean gloomy thunderclouds come and storm begins. Waves pounce coast furiously, taking out from depth and casting ashore seaweed and hundreds live creatures appeared helpless when faced to natural disaster. Wind sweeps over the Antarctic meadows, and grasses wave under its inrush like ocean waves. The wind gathers the tribute from Antarctic dragonflies, carrying away tens of insects failed to hide to the sea, or throwing them to cold embraces of the Central Antarctic Glacier, where helpless insects will simply freeze in layer of ice. Once millions years ago, ancestors of Neocene Antarctic dragonflies have got in this world with wind gusts. And now their descendants repeat the destiny of their ancestors, being carried away to uncertainty. Most likely, they will be simply lost in waves and will be eaten by fishes, but they would be lucky enough, few of their number may colonize small island where there are fresh water and food. But now dragonflies can do only one thing – cling harder to grass by legs and mandibles and wait while storm will finish.
Nature can not behave violently eternally, and sooner or later clouds move away, and the sky becomes clear again. Polar day goes on, and the sun quickly warms up the ground. And insects return to life habitual for them. For “black emperors” escaped during the storm there comes the time when it is necessary to work hard to get food for them. Delicate thin insectfish imagoes which obviously can’t resist to winds, most likely appear carried away to the sea, or freeze on the surface of glacier, giving food to hundreds of thousands of microscopic cold-resistant springtails. And other dragonflies are too strong and it is not so simply to catch them. But nevertheless there is something attractive to “black emperors” in storms. When the sun begins to warm again, from the coast the smell irresistibly appetizing from the point of view of these dragonflies is spreading – the smell of death and decay. Hundreds of fishes and other animals cast ashore began to decay, and in air there is a biting stink mixed with pungent smells of rotten seaweed. For the carrion-eating dragonflies it means the invitation to dinner, and shortly after air will get warm enough at the coast hundreds of these black-winged dragonflies already feast. Even falcon grackles flying after storm to the coast glance cautiously at this swarm of wing-rustling creatures. If there is a lot of meal, one or two birds, having taken courage, may steal fish or dead squid, but more often they should wait while dragonflies will be saturated or to wander knee-deep in water, gathering fish on which these dragonflies can’t land from fear to wet their wings.
The giant shadow of nomad albatross slides along the coast. This bird is one of the largest flying creatures of Neocene. Its wingspan reaches five meters. Being the true lord of heavens, it is rather clumsy on land because of long wings, therefore it does not risk to land near to impressive thick-billed penguigulls.
When the huge shadow of this bird slides at the beach where dragonflies are fed, insects are frightened and fly up. They may not to be afraid of this giant bird – nomad albatross will hardly pay its regal attention to them. Its appearing here is as if a reminder for feasting dragonflies: yes, they are kings of air, but at this continent only.
insectfish (Tenuidryas fasciatocauda)
Order: Dragonflies (Odonata)
Family: Demoiselles (Calopterygidae)
Habitat: Antarctica, slowly flowing rivers.
During the second half of Cenozoic era Antarctica was completely covered with a layer of ice which reached the thickness of several kilometers. The glacierization of continent had completely destroyed fauna of freshwater fishes and other animals living in the rivers and lakes. When in Neocene this continent began to free from an ice cover, at the plains and in mountains numerous streams and rivers with cold and crystal-clear water had appeared. They remained lifeless not for long: the wind brought from the nearest continents (Africa and Australia) spores of algae which roughly developed in absence of competitors. And when Antarctica had even more put in Indian Ocean, its reservoirs had been settled by higher aquatic plants, whose seeds have got there with a wind or on plumage of birds.
Among pioneer insects of Antarctica there were dragonflies. In a new inhabitancy, lack enemies and competitors, they have roughly evolved and even managed to occupy the ecological niches occupied by fishes at the other continents. And day-flies and caddisflies, living at the adult stage not for long, have not reached Antarctic Region: the oceans separating continent from other world are too wide for it.
Graceful dragonflies rush above the Antarctic rivers in large swarms. They are rather small (wingspan about 5 cm) and look very fragile. Body of such dragonfly is very thin, black with white cross strips on abdomen; wings are absolutely transparent with dense grid of costae. These dragonflies eat midges and other tiny insects breeding plentifully in crystal-clear water of Antarctic rivers originating in mountain glaciers. Life expectancy of each separate dragonfly is insignificant: no more than 1-2 weeks. But they start to appear as soon as air gets warm enough, and danger of night frosts will pass. And last of these dragonflies may live almost until the Antarctic polar night.
The role of this species of dragonflies in ecosystem of Antarctic rivers is very great: it is one of the basic inhabitants of the rivers. The adult insect, however, does not play as great role in natural communities, as its nymph does. Even the name of this insect – stripe-tailed insectfish – is determined not by appearance of adult dragonfly, but by features of anatomy and way of life of its nymph.
Nymphs of insectfish live in water, not betraying the “traditions” of ancestors (however the dragonfly from Hawaiian Islands, which nymph lived on land, and also nymphs of many fossil dragonflies found in land sediments had been known to people). It keeps in thickness of water in schools like small fishes and occupies their ecological niche in the rivers of Antarctic Region. The insect swims actively, wriggling the whole body in horizontal plane that increases its external similarity to fishes even more. Nymph’s body is extended and flexible, its length is up to 3-3.5 cm, colored grayish-white.
Living in clean water, insectfish nymph is guided mainly with the help of sight. Its eyes are well advanced, making about half of the size of head. To recognize congeners, nymphs have the special marks well distinct from afar: external gills on the tip of abdomen have contrast colouring – white with black tips.
Nymph also feels the presence of congeners with the help of sensory hairs covering its body. Every nymph feels movements of congeners and tries to imitate them in everything. Due to such behaviour the school of insectfish nymphs swims with remarkable synchronism, looking like school of fishes. The larval stage at this species proceeds up to 2 years, and in cold mountain lakes it may drag out twice more.
Like nymphs of all other dragonflies, nymphs of stripe-tailed insectfish are carnivorous. They eat tiny aquatic animals, catching them with the help of narrow labial mask with two palps (labial mask is in fact a modified labium working as a hand, characteristic for dragonfly nymphs). The basic food of these nymphs includes tiny swimming worms and plankton crustaceans, and also its own smaller relatives.
Adult damselflies of this species breed by disseminating their eggs above water. One damselfly may lay up to 100 tiny eggs. They ripen in female’s oviducts for a long time and after their appearing in water from them at once tiny nymphs burst, which hide in thickets of aquatic moss. Having reached the size of 1.5-2 cm, they gather in schools and spend more and more time in thickness of water, turning to pelagic animals.
of hearts” damselfly (Titanagrion rubra)
Order: Dragonflies (Odonata)
Family: Narrow-winged damselflies (Coenagrionidae)
Habitat: Antarctica, slowly flowing rivers and lakes.
Picture by Alexey Tatarinov
Among dragonflies amazingly beautiful species may be seen frequently.
Some of them amaze with brightness and metal shine, others with refinement of
their shapes. Among dragonflies of Antarctica one large damselfly having wingspan
of up to 20 cm is especially remarkable in its beauty. It has got a name “queen
of hearts” quite reasonably – only few insects of such size and such bright
colouring may be found in the world. Imago of this species has transparent wings,
and the whole its body is red with brownish shade. The damselfly has the right
to have such bright colouring: it is supported with unpleasant taste and warns
predators that the insect is protected. “Queens of hearts” fly only in the hottest
weeks of Antarctic summer.
Nymph of this species takes very important place in ecosystem of Antarctic freshwater bodies. It leads pelagic way of life and is very large (it reaches length of 10 cm and more). Legs of nymph are covered with hairs and are rather long (about one third of the general length of an animal). Their basic function is to promote hover of the nymph in water thickness. Usually they are simply spread wide in sides. But in case of danger “queen of hearts” nymphs can swim quickly, moving their legs like a larva of predatory water beetle.
Mask of “queen of hearts” nymph is wide; along the edge it is supplemented with a plenty of hook-like bristles. Nymph eats small planktonic crustaceans, filtering them with its labial mask. Thus the mask makes “raking” movements, at the same time helping the nymph to swim forward. After every “rake” mandibles accurately remove from mask crustaceans got stuck between bristles.
insectfish (Macrocryodryas vorax)
Order: Dragonflies (Odonata)
Family: Demoiselles (Calopterygidae)
Habitat: Antarctica, rivers and lakes.
At the Antarctic continent which had released in part from an ice cover in Neocene, the same situation, as at the islands, but in scale of the whole continent had repeated: actually uninhabited land had been occupied by few animals able to fly, or by natives of the sea. Isolation of Antarctica from other continents appeared reliable enough: not all possible migrants managed to cross ocean even to reach this ground only. But those ones which had made it faced the conditions far from being the best: the continent is located mostly within Antarctic circle, and in winter here is the polar night, and the ground is covered with thick layer of snow. But nevertheless the population of this territory is rather diverse.
In Antarctica of Neocene epoch birds are found, and also there are numerous insects.
Among insects in Antarctic Region dragonflies are especially widespread. These winged predators occupy top levels of food pyramid in reservoirs, and in a biomass they are comparable to migrating birds spending summer at this continent.
One reason of high variety of the Antarctic dragonflies is the absence of competitors in fresh waters. Fishes of Antarctic Region are mainly marine ones spending in fresh water only a part of their life and not rising in rivers far from sea. And cold mountain streams and lakes having no connection to the ocean represent an empire of insects. In water thousands of small damselfly nymphs slide, wriggling their bodies. Here they substitute fishes. Microscopic worms, crustaceans and other inhabitants of water turn to their food. At the bottom mosquito and fly larvae swarm, on stones and the rests of plants midge larvae form true live “carpets”. But, though here there are no fishes like a trout, in this world there is a king of predators – it is a large (up to 10 cm long) gluttonous nymph of voracious insectfish.
This species feeds on large insects, preying them one by one. Its basic hunting device is its labial mask (the modified labium). Palps on mask form some kind of “spear” piercing prey’s covers. Nymph stabs its prey, sharply darting mask in it (the length of mask in straightened position makes up to half of length of the whole body of nymph). Stab is put by palps nestled against each other that penetrates through prey’s covers. Having pierced an armor of prey, palps spread apart, having “anchored” inside and holding prey.
For predatory behavior and a mode of nymph movements this species of animals has a specific epithet “voracious”. It is a relative of smaller species of insectfishes and one of large species of damselflies of Neocene epoch.
After two years of “piracy” life nymph undergoes metamorphosis and turns to adult insect. An adult damselfly is about 12 cm long, its wingspan is up to 15 cm. Wings are transparent; males have narrow cross stripe of green color closer to the tips of wings. Abdomen of adult damselfly is colored metal green, and abdomen tip is yellow, separated from the background coloration by black cross strip.
Imago lives not for long – about one week only. Insects of this species emerge in strictly limited period: in two warmest weeks of Antarctic summer. At this time they continuously fly above lakes, searching for the partner for pairing. The specific epithet “voracious” does not fit absolutely to adult damselfly of this species. Imago has a digestive path and the mouthparts, but it eats much less than adult damselflies of other species.
Imago only lays eggs, landing on floating plants. After that its organism promptly grows old, and it perishes. Nymphs live among floating plants, avoiding in such a way a competition to benthonic forms. For wintering nymphs leave floating plants, hiding in thickets of coastal plants. Spring is the most difficult time for them: floating plants have not grown up yet, and nymphs, having flocked in thickets, begin to attack against each other. But when floating plants form a mat on surface of water, the survived nymphs feel like in full safety: they will not be found by gluttonous benthonic nymphs of other dragonflies, and the casual bird will not peck them up from surface of water – leaves of plants cover them from aerial predators.
stream dragonfly (Cryolibella platyglossa)
Order: Dragonflies (Odonata)
Family: Skimmers (Libellulidae)
Habitat: Antarctica, fast-flowing streams and rivers.
Picture by Lambert
The rivers of Antarctica originate in glaciers and are remarkable
in crystal-clear and cold water. They hadn’t been settled by insects like day-flies
or caddisflies though at the other continents they prefer such habitats: it
is very difficult for these species to cross the seas separating Antarctica
from the world around. But other insects have easily made it, having filled
with life rivers of Antarctica.
Stones in channels of Antarctic streams are densely covered with “live moss” – colonies of pearlworts and other sedentary animals. Here diverse midges which have got to this continent with winds have found the new house. Midge larvae settle on stones and plants plentifully. But here they have an enemy – the nymph of one local dragonfly species, flattened stream dragonfly.
Dragonfly nymph of about 7 cm long with the wide flat body covered with rudiments of wings slowly creeps on stones. It lives in streams with fast current, but is not afraid to be washed away by water. Nymph is perfectly equipped to life in the world of current water: on all its legs strong suckers are advanced. To make a step, nymph lifts legs one by one and by turns stand them on new place. In addition its body shape is those, that water itself presses this nymph to the stone. Of course, this mode of movement is very slow, but prey of this nymph is even slower: midge larvae spend almost the entire their life, being attached to the same place.
Labial mask at this nymph is short, wide and flat, with cutting front edge. Palps growing at the edges of mask are mobile and work as thumbs. When feeding, nymph grasps sedentary midge larva with palps and simultaneously cuts it off from substratum by edge of mask.
The development of nymph lasts for 2 years. Having reached the maximal length, it creeps to the riverbank and sheds skin, turning to adult dragonfly. Adult flattened stream dragonfly has transparent net-patterned wings and flattened brightly colored shining abdomen seen from apart. At male abdomen is silvery with bluish shine, reflecting a plenty of ultra-violet rays. At female abdomen has metallic-blue color, but on each segment there is cross belt of hair, also reflecting ultra-violet light. Therefore insects can distinguish representatives of another gender from afar: they see the “ultra-violet” colouring hidden from the naked eye.
But in the morning it is important to be warmed and to fly up in proper time, and shining abdomen obviously does not promote it. But the head and thorax of this insect are colored velvety black and quickly get warm in the morning. Adult flattened stream dragonfly keeps an orientation of diet characteristic for its nymph: it also eats midges, but adult ones in this case. Its legs are covered from the inside with hairs forming true “plankton net” for smaller flying insects. Darting through swarms of midges, this dragonfly catches some midges for one rush and eats them in flight.
During the summer female lays eggs for some times. For this purpose it lands on thickets of aquatic moss protruding from water, and puts its abdomen into the tangle of stalks, pasting eggs to moss shoots. Soon nymphs hatch from eggs. They eat the animals living in vegetation, and frequently larger nymphs eat smaller ones. Having got stronger, nymphs leave moss and begin hunting midge larvae in stream channels.
emperor” (Aeschnomima imperialis)
Order: Dragonflies (Odonata)
Family: Hawkers (Aeschnidae)
Habitat: Antarctica, slowly flowing rivers and lakes.
Picture by Alexey Tatarinov
In the world of insects there is as eager struggle for existence,
as among large animals. Here there are predators and prey also. A difference
is only in the number of participants of this struggle.
Because of its isolation from other continents Antarctica had been populated only by few founder species. Not all settlers got accustomed to extreme conditions of this continent, but those ones who managed to adapt, became the true owners of the continent. Among the Antarctic insects there are species comparable in ferocity and force to the most dangerous predators among vertebrates (of course, adjusted for the size).
Throughout the summer above the wetlands of Antarctica swarms of mosquitoes and midges hover. Small graceful damselflies dart through clouds of these insects, hunting them. But these thin-bodies damselflies may fall prey to a predator. They are hunted by birds, but it is rather easily to hide from chase of feathery predator: damselflies are much faster and nimbler than they are, and besides even from afar notice the birds flying by above endless thickets of graminoids and sedges. And the most terrible enemies of insects are other insects. And the top six-legged predator of Antarctica is furious “black emperor”.
“Black emperor” is a large dragonfly species, one of the largest insects of Antarctica. Wingspan of this species is about 18 cm. The body has metallic dark blue color with silvery cross strips. At male silvery strip on back third of abdomen is very wide. Shine of these strips allows insects to distinguish congeners during the prompt flight and to search for the breeding partner.
Black wings are of great importance in life of this insect: this adaptation allows to be warmed quickly in rays of the morning sun. During the sunrise this insect turns back to the sun, and its wings act as heat stores. Gradually the whole dragonfly is warmed up, moves its wings actively and flies up. It’s possible victims – dragonflies of other species – most likely still hang on grass leaves, relying on their inconspicuousity. But frequently shine of wings gives out their presence, and the predator gets breakfast almost for nothing.
At dragonflies not only adult insects, but also nymphs are predators. Nymph of “black emperor” is an active aquatic predator partly replacing small predatory fishes absent in rivers of Antarctica. Nymph is able not only to creep. It swims quickly, bending its body in vertical plane. It eats larvae of other insects, but prefers not to pursue them, but to attack from an ambush at the bottom. Nymph traps its prey, being dug in silt or under the rests of plants. The length of “black emperor” nymph may reach up to 10 cm – corresponding with an adult insect. Its colouring varies from brown up to pale yellow depending on color of bottom.
Its labial mask (lower lip) is very large, palpal lobes are saber-like and serrated on internal edge. They seize prey strongly, not giving it of chances to escape. “Black emperor” nymph attacks prey, using some kind of the “rocket engine”: it sprays a powerful jet of water from rectum. Such way of movement is characteristic for nymphs of large dragonflies in general. At this species it has considerably amplified: due to elastic joints of segments its abdomen can stretch strongly, taking a fair portion of water. Attacking its prey, nymph sharply contracts muscles and literally “shoots” itself from the shelter to its prey.
“Childhood” at “black emperor” lasts for about three years – winters in Antarctica are cold, and the period of active growth proceeds for some weeks only. Metamorphosis takes place more often at the fourth year of life though some nymphs turn to adult dragonflies already at the end of the third year of life. Thus, adults of “black emperor” may be met throughout the duration of almost all polar summer.
“Black emperor” is an insect with the serious claim for a rank of “super-predator” in the lightweight category. Sometimes this insect enters an antagonism even with birds. The seized dragonfly of this species protects itself actively: it bites, trying to get right to bird’s eye. Because of the bellicose behaviour it feels like in safety even at the presence of large birds, and smaller ones try to fly by this magnificent predator.
The interesting feature of this insect species is the adaptation of imago to feeding on carrion: it is frequently possible to find adult insects on corpses of sea birds or fishes cast ashore by storm. Sometimes adult dragonflies even pursue the predatory birds which have caught prey: this dragonfly has good sense of smell, and it sharply reacts to the smell of blood. Not being afraid of a bird, the dragonfly can land on its prey and be fed. If the bird will try to drive away the importunate messmate, the dragonfly attacks it itself, aiming to bird’s eyes. It can even frighten the bird off and take advantage of results of its hunt.
tern (Alcyosterna acutiptera)
Order: Charadriiforms (Charadriiformes)
Family: Dwarf, or Halcyon terns (Alcyosternidae)
Habitat: rivers and lakes of Antarctica, wintering in South America.
Picture by Pavel Volkov
In Cenozoic Antarctica was separated from other world by wide sea passages.
And the native fauna of this continent had been destroyed by glaciers. In Neocene,
when the glacier began to release edges of the continent gradually, at inhabitants
of other continents the opportunity to occupy free from ice areas of Antarctica
had appeared. Among them there were only those creatures that could fly. And
even among them only few managed to cross the sea and to reach Antarctica. But
at these lucky beggars the opportunity to evolve actively, occupying new and
atypical habitats had appeared. It had taken place so, for example, at terns
(Sterna): these sea birds have developed a source of food new to them – the
insects inhabiting Antarctica plentifully. Large birds became smaller and turned
similar to swallows both externally and in habit of life. So in Antarctica the
new species of birds had appeared – halcyon tern.
This species is a small bird: in size it exceeds sparrow slightly though it seems larger because of long tail. Wings at this tern are pointed, and tail is forked. But instead of short bill characteristic for swallows or swifts this bird is equipped with the strong pointed beak making more than half of total length of its head. Legs of halcyon tern had partly lost ancestral features: the palama does not reach even the half of toe length, but on toes pointed claws had developed. Halcyon tern is able to swarm up stalks of cane dexterously, and it is capable to perch on wavering plant stalk precisely at full speed.
The plumage of these birds gives out their relationship with sea birds: it is white, and only on head there is a black “cap”. Beak is yellow, and in mouth cut it is red. Legs are also red.
This bird eats small live creatures, catching them in water or in air. The basic prey of this bird includes dragonflies. They are eaten by halcyon tern at any stage of life cycle. It catches adult dragonflies, easily chasing them in flight, or gathering in the morning time from grass, while insects are not warmed up yet to fly up. In addition it dexterously snatches swimming nymphs of damselflies out from water. Probably, because of it this bird did not become an exact copy of a swallow, but combines in its appearance features of swallows and halcyons.
Halcyon tern is a migrating bird. It spends winter in South America though sometimes separate individuals, being obviously blown by winds, fly for wintering to Africa or to Madagascar. During the migrations this bird safely lands on water and can catch plankton organisms from sea surface. This bird flies to Antarctica in the middle of spring and flies out in the beginning of an autumn, when the number of dragonflies (their basic food) decreases.
As against other relatives, this bird does not form numerous congestions, nesting at the riverbanks at the distance of several meters between their nests. However, features of collective behaviour have still remained at them: birds drive predator away together, operating bravely and consistently.
Nesting takes place once a season and is dated to the beginning of warm summer days. Terns have no outstanding building talents and at times their building skill is limited only to the choice by the bird of a place where it will lay eggs, and this place simple becomes its native house without any preparations. Other species of terns build friable nests of vegetation on trees or on the ground. Perhaps, halcyon tern has reached the top of building skills, having surpassed in it of all its relatives. It nests in canes similarly to small songbirds of Holocene epoch, and builds nest in reeds by itself. The basis of its nest is made of some cane stalks meshed to each other, the part from which is broken. On such unsteady basis it makes nest looking like friable basket with low walls. In clutch there may be up to 5 eggs. Female hatches chicks mainly. Chicks hatch with opened eyes and covered with grey down with black longitudinal strips. Chicks dried after hatching at once seize nest by claws; they would not drop out of it even at high wind.
Development of chicks takes about five weeks. Young birds find the way to wintering areas independently. Sexual maturity comes at them at one-year-old age, and life expectancy makes about 8 years.
This species of birds is discovered by Simon, the forum member.
penguigull (Sphenicilarus crassirostris)
Order: Charadriifoorms (Charadriiformes)
Family: Penguigulls (Sphenicilariidae)
Habitat: sea coast of Antarctica.
The majority of species of inhabitants of Antarctica avoids meetings with winter. Small animals like insects simply go into hibernation, having hidden in secluded places under vegetative dust. Other ones like the majority of birds simply fly out to the north, to warmer areas. Some of them hasten to South America, others winter in Africa. But some birds keep activity the year round, not leaving the native land. Those, for example, are small mousebirds digging holes in thickness of snow during the whole winter. But there are also larger inhabitants in Antarctica. They may be found out at the coast of ocean – trumpet voices of these birds are audible from far.
After the ecological accidents which had taken place at the boundary of Holocene and Neocene, the number of sea birds like penguins had greatly decreased, and they had died out soon. But to change them the strange birds evolved, being also not able to fly. They were descendants of gulls, flightless penguigulls, birds with flipper-like wings, searching for food in the ocean. At Subantarctic islands rather small common penguigull (Sphenicilarus apterus) lives, but in continental Antarctic its larger relative – thick-billed penguigull – lives. Like its smaller relative it forms the colonies numbering up to two or three hundreds of birds.
Thick-billed penguigull is sea-dwelling flightless bird similar in constitution to penguins and auks. Growth of this bird reaches almost one meter. Legs are shifted back, therefore during the movement on the ground bird keeps its body in vertical position. But in water it feels like as freely, as a fish, propelling itself with wide paws equipped with palamae. During the swiming bird also uses the reduced wings covered with very dense feathers. It swims in a manner of penguins and sea lions, making by wings the same movements, as at flight. It is able to dive deep (up to 60 meters), eats schooling fish and invertebrates – krill and small squids.
The body is colored bluish-grey from above; head and stomach are white. Beak is very deep, of yellowish-white color. On edge of lower jaw bright red strip stretches – it is a signal for chicks during their feeding. Giving food to chicks, the parent regurgitates the caught animals so that they appear as close as possible to this strip, and the chick instinctively pecks this strip to find food.
Thick-billed penguigull spends the year round at the coast of Antarctica, preferring stony beaches. When at the end of spring the ocean will get warmer and numerous small animals appear there, the courtship season begins. Pairs are formed only for one summer. Courtship displays are accompanied by loud calls and sometimes males even combat, seizing each other by powerful beaks against wing or nape. Courting for the female, male feeds her with fish. The pair of birds arranges the nest (they dig simple pit among stones) and female lays two or three motley eggs. Mainly female is engaged in incubation, and male is busy in food getting for the most part of time. Chicks hatch covered with brown down with small black spots. They have opened eyes and are mobile, are able to walk, but prefer to remain in nest for the sake of their own safety. From all sides each chick is surrounded by neighbours which strive to peck another’s posterity every time.
Young birds differ from adults in one-colour beak lack of red strip. It will appear at the third year of life, and it will mean that the bird became adult and is ready to get its own posterity.
In winter birds of this species frequently appear on ice. Sometimes ice floes, breaking away from the main ice mass, carry away birds to more northern latitudes. But thick-billed penguigulls always can return home after such incident: they are able to swim for some days in succession, having an occasional rest on small ice floes or on other floating objects.