In Neocene the geography of Atlantic Ocean has appreciablly changed compared to Holocene epoch. Since the end of Mesozoic and during the whole Cenozoic, this relatively young ocean expanded gradually. In Neocene this expansion has resulted in change of direction of circulation of waters, which had a radical influence to live creatures inhabiting this ocean. Break of North and South America has caused the occurrence of Panama current directed to Pacific Ocean. In addition, closing of Bering Strait by Beringian isthmus at the collision of Eurasia and North America had another, but not less serious consequences. Arctic Ocean has actually turned to the huge whirlpool contacting only to Atlantic. Along the coast of Greenland warm Gulf Stream flows in it, and in opposite direction along the coast of Northern Asia and Europe from Arctic Ocean cold Antigulf Stream current moves, causing in general colder climate of Europe than it would be expected in Neocene at the background of the general warming of the Earth climate. In the central part of Atlantic Ocean the slow whirlpool has appeared, in which masses of brown macroalgae grow. This whirlpool is “swirled” by warm Gulf Stream and its cold European “twin”, and its way in partly blocked by large island of volcanic origin – former underwater Azores Plateau. In this place water from the depths, carrying plenties of phosphates and nitrates, rises up the slopes of Mid-Atlantic Ridge to the surface, causing rough development of plankton and floating algae.
The passing from Holocene to Neocene was marked with natural catastrophes and their indispensable attendant, the mass extinction, which has influenced the majority of groups of sea- and ground-dwelling animals. After the ecological crisis the oceanic fauna had changed dramatically. Results of mass extinction appeared especially deplorable for inhabitants of open ocean. Many groups of the ocean animals typical for Holocene became rare in Neocene, and even died out completely very often. It was mainly a fate of the species occupied the top level of food pyramid – large sharks and sea mammals, and also the species feeding on plankton or spending a part of their life cycle in plankton. Dolphins, whales, seals, various sharks of open ocean – everyone dependent on plankton or animals eating it – have died out completely. The specialized fishes of open ocean – herrings, tunas, jack mackerels, swordfishes and other nomads and outrunners of the seas – have disappeared. Among planktonic animals many groups become extinct, and survivors were present as pitiful remnants of the former diversity.
When biological productivity of oceans began to restore in Neocene, an advantage in survival was received by the species possessing the great rate of alternation of generations to the moment of catastrophe. It has permitted them to restore their number quickly after the crisis. Having this advantage, survived animals have substantially changed the appearance of oceanic fauna.
The fauna of temperate and subtropical areas of Northern Atlantic is remarkable in its originality: now the main competitors of fishes – pelagic squids – dominate here. These molluscs having short life cycle and breeding near the coast appeared less subject to influence of ecological crisis. Of course, fishes are also present in the ocean, and their species are numerous, but in communities of open ocean, they do not form mass congestions any more like herrings or mackerels in Holocene epoch and stand in the background. Far from ocean coast, squids have almost superseded fishes from small and medium size class. Nevertheless, fishes still occupy the top of food chain, though here again, squids have made successful attempt to encroach their domination.
In heat of day on the surface of water smooth shining backs of rather large live creatures appear. Can they be the last representatives of dolphins? No, they aren’t: above water the characteristic fountains arising at an exhalation of these animals do not rise. And in addition they move absolutely silently, while dolphins breathe noisily and actively communicate with each other with the help of sounds.
Suddenly these creatures accelerate movement, and wet backs hide under water for any time. In some seconds after that on the surface silvery fish sides flash – unknown underwater hunters have surrounded a shoal of young fish. Water literally boils: fishes obviously try to escape, but they are surrounded and trapped. Suddenly one hunter jumps out from water, and its origin appears clear at once. The elongated body of this creature is equipped with two wide fins on sides, and is ended with… arms instead of tail with flukes. No, it is rather not ended, but begins from them – it is large cephalopod with short arms, and it moves on backwards like all its relatives. The animal dives into the center of the surrounded fish shoal, and it is followed by another one of the same kind. Attack of fishes was carefully planned and put into practice correctly. These creatures are jumping squids belonging to the most successful predators of open ocean.
It is clearly seen in the water, how squids hunt fish. They surround a shoal of fishes, and do not let them to escape from the trap, pushing them to water surface. From time to time one of these animals rushes across the congestion of prey and emits a transparent yellowish-brown liquid. Having appeared in the cloud of this liquid, fishes convulse and emerge belly-up. Holocene squids were equipped with their ink as a chemical weapon, and at their Neocene descendants it had turned from the protective weapon to offensive one. When in water there are numerous fishes stunned by poison, squids grab them by arms one by one, and eat. Such hunting is rather safe for squids – immunity to their own poison is developed at them.
Squids communicate with each other by means of color signals, but the fishes surrounded by them splash loud, jumping out from water, and produce alarm signals. Using such sounds, other inhabitants of ocean learn about the good luck of squids, and also hurry up to get the portion of meal for themselves in their feast.
Melodic voices of fishes similar to sounds of gong and chirp reach far away in the ocean. These are voices of large predatory fishes, shovel croakers. A school of these fishes, sparkling their sides, moves towards the place of squids hunting. From the blue haze the silhouettes of these deep-bodied fishes appear. Having gathered in numerous school, they keep at some distance, being afraid of influence of squid poison; otherwise they can fall prey of these molluscs. But also squids try not to swim up close to predatory fishes – their soft bodies would be broken off easily by sharp teeth of shovel croakers. Acting together, squids can create a “chemical veil” usable for protection, which can poison even a large fish. So original “parity” is established between competitors.
Squids eat a part of fishes stunned by poison, and retire hastily – they are disturbed with the presence of croakers. Seeing that squids swim away, croakers do not waste time, and pick up other fishes while they have not come to the senses. The rests of the shoal of small fish disappear in blue haze at this time.
Plankton is a basis of biological productivity of the ocean. Billions of tiny organisms breed in water at the great rate, painting wast spaces of the ocean pinkish, greenish or whitish color. Pinkish color of sea pastures means, most likely, the congestions of small red mysid crustaceans, and whitish is caused by tiny jellyfishes and other transparent animals. Among planktonic organisms the majority of species is feeding on microscopic algae and animals, and some kinds ae active predators. Jellyfishes, fish fry and large forms of planktonic crustaceans are real monsters, gluttonous and ruthless, though their length makes sometimes only about two centimeters. Some of them are armed with the longest tentacles containing cnidocytes, others have sharp maxillipedes with strong grip, and somebody else has long penetrating proboscis. But they all appear helpless, having got in simple, but effectively working trap.
In water near the surface the whole clouds of swollen slime similar to viscous kissel float. If any planktonic monster will casually touch them, it is pasted to slime at once and can not free itself anymore. It can only wait for its inevitable fate, when the owner of the trap will start to harvest its “crop” of tiny animals trapped in the same way.
The owner of this trap does not leave it from fear that some of its congeners may take advantage of its catch. This creature looks rather unusually, resembling more a certain hallucination: it has transparent flesh, through which interiors and the pulsing heart are visible, the extended head with large spherical eyes on stalks, and mouth extended to a proboscis. On sides of the body animal has wide delicate wings, and from behind its body is extended to long “tail”. Strange appearance and transparent body have determined the creature’s name – it is the sea ghost. Its close relative is astarotus – a predatory mollusc from Caribbean Sea. Sea ghost is giant planktonic gastropod, and its diet includes other planktonic inhabitants. But this predator does not chase its prey like astarotus does, but prefers passive hunting. Emitting from its mouth dense saliva secreted by hypertrophied salivary glands, this mollusc makes traps for plankton. In water its saliva swells to sticky slime, in which tiny creatures stick. Sea ghost eats plankton of numerous species, not giving preference to any of them – it is more favourably, because in this case there is no dependence on any limited food source. To not lose its trap, the mollusc frequently holds one edge of the trap in its mouth. When a needed amount of plankton will stick to slime, this mollusc simply swallows slime together with the caught prey. Thus the animal actually does not waste energy for movement: prey comes into its mouth itself. But all the same the sea ghost should swim for a while sometimes: not only this gastropod feeds on plankton, and it is not the largest species among plankton devourers.
In planktonic fog a strange silhouette moves, giving rise to thoughts about mythical monsters invented by human imagination. This creature has big-bellied body, long tail and large head. When it comes nearer, two rather short pectoral fins waving like wings and propelling this monster forward become visible. It is one more plankton devourer – the sea wyvern, an original ecological analogue of a sunfish. It has repeated in part an evolutionary destiny of this dyed out fish: like sunfish, sea wyvern also descends from the stock of coastal fishes which had adapted to the life in the open ocean. But its ancestors were harmless sea horses. One of their species survived during the crisis in coastal waters of tropical latitudes has successfully developed open ocean, having turned to this grotesque sea monster.
The fish of five-meter length swims, turning its head from side to side, and flapping its wing-like fins evenly. When the monster comes closer, the sea ghost swims away – this fish is dangerous for invertebrates and can easily swallow even a large planktonic mollusc. However, sea wyvern prefers not to hunt mobile creatures which need to be chased for a long time. It is interested mainly in live food which can not get away farther than half meter from its mouth. The slime trap with plankton abandoned by sea ghost appears very opportunely for it: having sticked its long snout into it, sea wyvern opens its small mouth and in strong movement of operculums involves in it water together with a part of the trap. Having finished in some seconds with a gratuitous entertainment, dragon-like fish continues its way. Sea wyvern reaches a congestion of tiny and almost transparent jellyfishes. Here there are only few fishes and small invertebrates: jellyfishes are poisonous, and the touch to their burning tentacles is very dangerous. Tentacles of jellyfishes form a true network in water, which stops every creature longer than some millimeters. But sea wyvern is not going to be caught in this network and to become a dinner for jellyfishes at all – on the contrary, it swims here to have a good dinner. Having reached up to the congestion of jellyfishes, the sea giant begins absorbing them one by one like a live vacuum cleaner, swallowing entirely with burning tentacles. Poison does not harm this fish – sea wyvern has immunity to poisons of every possible planktonic organisms allowing it devouring of everything floating in thickness of water without any harm for itself. Scared by sharp movements of the fish, some jellyfishes try to escape, but tube-like snout of sea wyvern overtakes them with ruthless accuracy. Nevertheless, one jellyfish succeeds to escape, having torn off the tentacle appeared in the mouth of this fish. One more monster of the same kind is feeding not far from this one. Usually a meeting of sea viverns is a very rare event, though females ready to breeding involve numerous males forming their “honor escort” until female will spawn with one of them.
Thickness of water is settled much denser than it seems at first sight. Sometimes only casual flash of the sunlight gives out the presence of numerous, but completely transparent animals. In this way they succeed to avoid in some extent an attack of plankton-eating monsters like sea wyverns. In sun rays near the surface of water the fast live creatures swimming in a numerous school gleam. Only silvery lining of body cavity masking interiors and large eyes like sparkling greenish fires when sun light hits them give out their presence. They quickly change direction of movement, catching large planktonic crustaceans by almost transparent arms. These sea phantoms are crystal squids, one more variety of cephalopods. These animals spend their whole life in plankton, and do not approach to coast even to lay eggs. These planktonic molluscs are translucent and almost invisible for sea wyverns. In addition, they swim much faster than these fishes and consequently never get to their dinner table, except for dead ones.
At night the surface of ocean lights up with flashes of light emitted by various planktonic creatures. Congestions of unicellular sea sparkles (Noctiluca) shine brightly, from time to time in thickness of water like bluish rockets salpae rush; in daylight these ones are actually invisible. Bells of small jellyfishes shimmer with flashes of white, greenish and pink light.
The sea ghost, giant gastropod, swims under water surface, flapping its “wings” like a ray. Now it is the best time for its feeding: planktonic organisms from depths emerge to the top layers of water, and the animal searches for a place to arrange its slimy “network”. At night in traps of sea ghosts even small deep-water fishes get, coming to the surface for the food. Having chosen for its feeding a place where planktonic crustaceans are numerous, the mollusc opens its mouth, and its salivary begin secretion of slimy trap. But it seems, here it is nothing to eat for this one: something denser runs at full speed into a soft body of sea ghost, rushing aside on the spot. Bright flashes of light dazzle the pelagic gastropod, and certain luminous creatures begin to turn around its head. One crystal squid, which school has also chosen this place for feeding, collided with the sea ghost. Bright light was a reaction of scared cephalopods to an unexpected meeting. At night crystal squid shines extraordinarly brigh: its whole body is spangled with tiny luminous organs, and flapping fins describe fiery “zigzags” in water. Scared by unexpectedly bright light, the sea ghost swims away far from fussy cephalopods, which quickly calm down and continue their feeding. They “wink” each other with short flashes of soft blue light. Unfortunately for itself, one squid runs at full speed into the slime secreted by sea ghost. Having got in the trap, this mollusc claps its fins intensively, trying to free itself. Thus the body of the annoyed squid begins to shine brigher, and blue fire runs along it in waves. Having noticed it, other squids muffle their luminescence and swim aside, having almost disappeared in darkness of night ocean. But the crystal squid is larger, than animal usually consumed by sea ghost, therefore it frees itself very soon, having torn a slimy trap to pieces. The disturbing luminescence is replaced with usual soft flashes, and the school of squids reunites.
The majority of the sea animals able to bioluminescence seldom makes it all the time. They usually flash brightly, if someone disturbs them. The way of a sleepy fish across the school of tiny luminous animals is marked by flashes of light or by a long luminous strip slowly fading in darkness. But sometimes the sea begins to shine especially brightly. Through flashes of blue and yellow light silhouettes of giant creatures move. They are similar to whales, but they are giant fishes – cachalot sharks, the largest fishes of Neocene epoch. They live in depths, but swim up to the surface of ocean for night feeding.
Night is a time when various inhabitants of depths make vertical migrations for feeding in productive top layers of water. These migrations take place nightly and reach great scale: twice per day tiny creatures overcome the distance in hundreds meters in vertical direction. Shoals of tiny animals – crustaceans and fishes – rise from depths to the surface, and predators of small and medium size from the top layers of water eat them. Each shoal of small fish or crustaceans attracts large predatory fishes hunting at night, and flashes of light near the surface of night ocean mark their attacks. Besides some large animals living at the surface of ocean simply sleep at night, and in this condition it is easy to catch them by surprise. They exactly represent a prey that cachalot sharks hunt. They eat all large inhabitants of the ocean, both fish and squids. They willingly feed even on the carrion, eating sometimes corpses of their own congeners.
When such monsters make their living on the surface, the inhabitants of the ocean active in daytime try to hide from them as good as they can. Favourite “bedrooms” for inhabitants of the open ocean are the floating macroalgae. To the south of volcanic New Azora island formed at the place of Azores, sea currents have “swirled” an immense whirlpool, in which brown algae expand plentifully. Sometimes whimsical storm tear off from algal fields small pieces, which float to northern waters, and at times reach even coasts of Iceland and Greenland. While they “travel to nowhere”, various sea animals use these floating islets of algae as a refuge during the night rest. In one such islet a numerous school of shovel croakers was bedded down. At night these fishes change their coloration: from silvery blue they become cross-striped, on their bodies thin black strips appear. The school of croakers hided deep in floating algae, and fishes sleep tight. They slightly move with operculums and from time to time try to move deeper inside the algae. Not only fishes sleep at night – the school of jumping squids has also fallen asleep in algae floating near the surface of water, having chosen, certainly, a place far away from predatory croakers. Animals turn pale, slightly move with their arms in dream, occasionally wave fins, moving from one place to aother. Near to sleeping jumping squids transparent slimy capsules wave, and inside them there are spherical eggs. These are clutches of crystal squids laid some days ago.
It is impossible to tell, whether these animal see any dreams, and whether they have nightmares. But the reality of life in the ocean is those that nightmares can come not in dreams, but in reality. Having woken up in time, it is possible to get rid and of them, but it happens so not always. When jumping squids sleep, one ocean inhabitant has real chance to enjoy their flesh. Usually in daytime these molluscs easily escape any hunter, but night equalizes chances of both predator and prey. Under floating algae, where these squids spend the night, a giant creature moves, exceeding any of them in size several times. Moonlight shines in huge eyes of this creature – the representative of one more cephalopod species. Its silhouette resembles the outlines of large dolphin or shark – fins of this mollusc are long and rather narrow. It is one of the most successful species of cephalopods of the open ocean, orca squid, gluttonous predatory mollusc. It is one of the most dangerous animals of the open ocean, successfully competing to vertebrates. When night has come, the mollusc has began its hunt for various animals. Orca squid is ready to eat any animal which it can overcome. It uses for hunting the chemical weapon, but of a different kind, than jumping squids use: in parallel to octopuses it had developed poisonous glands in beak, therefore even rather large animal perishes in some minutes after its bite. In daytime this mollusk is inactive and prefers to hide in depth or among floating macroalgae, but at night it turns to one of numerous nightmares for other ocean inhabitants.
Using its sense of smell, orca squid finds jumping squids sleeping among algae. Having precisely determined their location, it begins to creep to molluscs from below: in this way the probability of being noticed is much less. Having floating in water a head up, it darts its hunting tentacle upwards in fast smooth movement, and grabs one of jumping squids. The tentacle strongly pulls together body and fins of attacked mollusc, and corneous hooks stick deep into its flesh, not giving an animal an opportunity to slip away. The only thing that the attacked jumping squid could make was to emit a poisonous liquid. But the orca squid has instinctively foreseen this opportunity: for this reason it attacked from below and from afar. The jumping squids disturbed by predator’s attack and woken by smell of poison of their relative, rush here and there, being half-awake, colliding each other and algae shoots. Some squids in a panic emit portions of poison in water that strengthens turmoil even more. At last, the school of jumping squids swims awau in all directions and disappears in darkness. Orca squid pays almost no attention to them. It simply dives deeper with its prey, avoiding the action of poison of jumping squids. In its first bite it has literally crushed gristly “skull” of the caught jumping squid, and now quietly tears off pieces of meat from its carcass by beak, hovering in thickness of water at the depth of about 50 meters.
Orca squid inspires fear to the other ocean inhabitants. Even in daytime, when it hovers phlegmatically in thickness of water, waving its fins lazily, no one fish will dare to swim up close to it. But is it really so? However, one fish nevertheless makes it, even without any risk for its own life. In this case, the orca squid itself risks its life when shows carelessness and does not seek safety in flight at its approach. One of few animals of the ocean able to overcome orca squid is a cachalot shark. In due course of evolution this shark species has partly replaced sperm whales, toothed whales dyed out before Neocene, and it became the prime cephalopod hunter. For squid hunting sperm whale used ultrasonic “locator”, finding out and even stunning squids with the help of narrow and directed “sound ray”. But the only problem of this hunter was its connection with surface of water. Sperm whale had to emerge for air, while large fishes and squids could stay in depth for unlimited time. Cachalot shark lacks this problem: like all its relatives it breathes with the help of gills and does not need atmospheric oxygen. It is not able to produce ultra sounds in way similar to whales, but it has feeling which they have lost. Sense of smell is a “secret weapon” of this shark. Nostrils of cachalot shark have a special anatomy which enables it to trace smells highly efficiently. Nostrils are not deep, but very extended in longitudinal direction. Their edges in the middle part are closed, and are opened on the ends – nostrils turn to tubes through which at shark’s movement water passes continuously. Using the keenest sense of smell, the cachalot shark easily chases orca squids in ocean depths. Usually during the hunting this fish swims flapping its wide pectoral fins like wings. But in rest it prefers to move in slower, but an economic way, waving its whole body. Squid can swim very quickly, but not for long. And in addition it can not hide its smell; it can swim faster than shark and can leave it far behind, but sooner or later fish will overtake it, having driving it up to exhaustion. And the only hope for a squid is that something will distract a predator from the chase.
Orca squid feels the approach of shark in proper time: flaps of its wing-like fins produce waves, which force and rhythm are correctly recognized by these molluscs. In addition, the squid has some tricks in a stock. First, its ink still has poisonous properties, and in “near fight” it can paralyse shark’s olfactory nerves. And next, having exhausted its ink stock, mollusc can hide in floating algae, which partly mask its smell.
Orca squid escapes from the shark pursuing it among the floating algae. Scaring away sleepy fishes, the four meter long animal runs at full speed into floating plants and squeezes deep inside their thicket. Having buried itself in algae, the orca squid freezes, and its skin aquires a pattern of brownish spots and strips to imitate a color of algae. But the smell gives it out all the same, and one minute later the huge shark like an enraged submarine literally rams a hidden cephalopod from below. Squid makes only a slight attempt to escape: all its interiors are damaged, and every movement causes a terrible pain. And the shark by impact of wide head from below throws it up in air to about ten meters upwards. Having described an arch, a hackneyed orca squid falls in water and jaws of cachalot shark close on its body.
Cachalot shark eats smaller prey, swallowing it entirely. However, it should tinker with this squid for a while – the body of a mollusc has fallen in algae, and the shark does not wish at all to spoil its supper with unpalatable brown “garnish”. It pulls a carcass of squid, dragging it out from algae, and tears only small pieces from it. At the water surface the wide head of this huge fish gleams in moonlight. On one side on its skin something looking like an outgrowth formed on a place of an old wound is visible. But when the shark’s head appears under water, this “outgrowth” moves. When near it a small scrap of meat of orca squid torn by shark floats, it becomes obvious, that it is not an outgrowth at all, but an independent live creature. This creature extends its long tentacle and dexterously picks up a piece of meat, which disappears somewhere under one edge of this creature. Strangely enough, but this parasite is also a squid of a separate species, a sticky skin squid. It belongs to the number of live creatures, for which a body of cachalot shark became the native house.
The inhabitancy for live creatures is not only air, water or the ground. Some species of live creatures have chosen organisms of other species of animals or plants as an inhabitancy. Even cachalot shark itself, being a terror of Atlantic, represents an inhabitancy for set of animal species. Havingg rhythmically flapping its giant pectoral fins, this fish is moving through thickness of water, and carries on its skin a true “zoo” of various parasites and symbiotes. Skin of cachalot shark is very thick and covered with tiny skin teeth. But some cirripedes, barnacles of the separate species, penetrate deep into it, forming numerous colonies on back and head of this fish. They actually do not harm the shark, because are not parasites. Having opened operculi of their shells, they take out their plumose legs covered with bristles, and catch the food particles floating by. Barnacles attached to the lower side of flat head near the mouth of shark have a little bit better position – they frequently get the rests of the shark meal. But they represent a completely different species which filters water less successfully compared to the variety, which representatives grow on back and sides of shark. On soft skin near gills of cachalot shark long (about one meter) outgrowths waving in water stick out: these are egg sacs of parasitic copepods. When they burst, millions of eggs appear in water.
Probably, parasites would exhaust a shark with their importunate “attention”, but, as it is said, “even the crocodile has friends”. The shark gives a shelter not only to various parasites and spongers, but also to assiduous cleaners. Of course, sticky skin squids pick up pieces of meat of shark prey from time to time, but nevertheless their basic occupation is absolutely different – it is hygiene of skin of giant fish. These original cephalopods had almost completely lost ability to swim in adult condition, and they spend the most part of life on bodies of giant cachalot sharks. Sticky skin squids make a living out of constant cleaning of shark’s skin by grater jaws, removing a dying off top layer of skin. In addition, they clean off various parasites from shark’s body. Because of these creatures barnacles chosen a shark for life immerse almost completely into its skin, having left on the surface of skin only a “hatch” for legs, which is densely closed by massive calcareous operculum. Squid attaches densely to the skin of fish by suckers, which are present not only on arms, but also on the bottom side of its flattened body. Moving its arms and dragging its body, the sticky skin squid can creep slowly on the body of cachalot shark, clearing various areas of its body. On the body of cachalot shark can live up to ten these molluscs at once, which keep its skin clean. They are in relative safety when attached to the body of a giant fish, and the only danger to their life arises only when the shark wants to scratch its skin against tree trunk floating in the water, or against skin of the relative.
Usually thick skin on shark’s head, back and sides is populated with parasites not so heavily. Another matter is soft and rich in blood vessels skin near gills and eyes. Here parasitic copepods frequently penetrate into it, being almost completely immersed into the skin of shark, absorbing nutrients from its blood. From outside only an egg sac giant compared to the crustacean’s body sticks out. At various species of these parasites egg sacs may be of different shapes – ribbon-like, rounded, and even bicorn anchor-shaped one. From egg sacs portions of ripen eggs appear all the time, and daily productivity of separately taken animal may be up to several thousand eggs. Having got to water, eggs develop rapidly and turn to pelagic larvae. Only few of them will manage to get on gills of other sharks, having finished thus their life cycle. Nevertheless, sometimes parasites do not succeed even to lay eggs. One of sticky skin squids creeps up to the shark’s eye, slowly moving its arms one by one and contracting its body like a giant worm. It scrapes the top layer of skin by its beak modified to the grater. The digestive path of this squid can cope even with such rough food. Nevertheless, sticky skin squid prefers something more delicate and nutritious. Egg sacs of copepods fluttering on shark’s gills are just acceptable as a food. Trying not to disturb a shark on which it sits, mollusc cautiously creeps up to them, “mows” them with its hunting tentacles and eats. However, some days later on their place new ones will grow – the body of the parasite hidden in shark’s skin remains unharmed after such “haircut”. Right in front of the squid there is a large eye of cachalot shark with golden iris of the eye. When the sticky skin squid casually touches this eye with its arm, it suddenly turns to its side and blinks. Maybe, the shark for the first time in its life sees in the corner of its eye one of those creatures that have settled on its body. Scared by sudden movement of the shark’s eye, the mollusc crawls away and begins clearing gill slits of its giant host.
In the morning in the ocean the resettlement of live creatures begins again. Deepwater inhabitants return their gloomy habitat, and inhabitants of the ocean surface wake up on the sly. The most part of cachalot sharks move to gloomy depths, but one of them stays near the surface. It is pregnant and ready to give birth to some juveniles within the following hour. The giant fish floats in thickness of water near the surface, smoothly bending its backbone and slightly moving its tail. The female seems constrained, but inside her body two more lifes are ready to be born, and they actively search for an exit to the “big wide world”. The spasm runs along shark’s body, the tail makes sharp movement – and from birth canal juvenile shark appears. First its head appears outside, then the egg membrane surrounding it brokes off, and gill slits and one pectoral fin appear free. Cub is not born entirely yet, but already begins to move its jaws and to pump water through gills. Birth pangs of giant shark go on, and cub eventually slips out into the water. It is surrounded with the rests of egg membrane, which surrounded it during its development. It is released from them in several sharp movements, and these membranes float in water like a dead jellyfish. The umbilical cord connected shark cub with its mother’s organism is torn now, and the cloud of blood blurs in water. The smell of blood involves jumping squids gathered around the newborn cachalot shark like pirates. After the break of its umbilical cord shark cub stays motionless for a certain time, and at this moment squids grow bolder: they swim and almost touch it with their arms. But young shark shows vitals: some convulsive movements, and it swims. One jumping squid swims up too close to the head of a newborn shark, and typical shark’s reaction follows immediately – the attack. Having rushed forward, shark cub snaps at squid, crushes it, and devours the first dinner in its independent life. Juvenile sharks at birth are armed with pointed teeth, and are independent since the first minutes of their life.
Newborn shark cub quickly swims off from the female – it lacks the bond to parent characteristic for whale cubs. And the female, in turn, having met its own cub in some days after its birth, can simply eat it. At birth, shark cubs survive due to suppressed feeding behaviour at the female, and such condition lasts at her within several hours after the cub delivery. Therefore, cachalot shark does not attack its own posterity, enabling cubs to hide.
Labor of cachalot shark female goes on. Having bent its body, she contracts muscles and gives rise to the second juvenile. It was born even faster than the first one. For some minutes it is almost motionless, then gradually begins to move and also swims away. Jumping squids tear and eat egg membrane surrounded it and continue to keep near to adult cachalot shark female.
Giant fish gradually recovers after the delivery – its muscles relax again, and ligaments contract. The shark becomes more active. She as if is afraid to believe that can live farther, as she did before the delivery. The fish slightly moves with its fins, and then makes unexpectedly intense swing of the tail. Squids scurrying around of it disappear from its field of view in few seconds – the shark became again the largest predator of the sea and the threat for all cephalopods.
Once, about half-century ago, its own life began in the same way, as the life of its newborn cub. For this time it had seen a lot of things: attacks of furious orca squids, insidiousness of coastal shallows during the outflow, tricks and dodges of various sea inhabitants, force and roughness of courtship behavior of males of its own kind. And her juveniles must learn the same things in due course of time.
Juvenile cachalot shark is independent since the first minutes of its life. It is compelled to care of itself, and must feed and escape from enemies by itself only. Of course, five meter long “cub” has not so numerous enemies in comparison to any tiny plankton inhabitant, and it can behave less cautiously sometimes. But sometimes sea inhabitants may give absolutely unexpected repulse to ones trying to hunt them.
Newborn cachalot shark crosses an area of the sea where islets of brown algae float, and swims to open water. Suddenly young predator views a strange and surprising show: feeding of sea wyverns. These fishes “graze” in a congestion of salpae – swimming planktonic animals related to primitivest vertebrates. Transparent bodies of these creatures are united to long chains and move quickly due to a jet principle. Flapping their pectoral fins like wings, sea wyverns chase and devour salpae, sucking them in by tubular mouthes. They tear long chains of these swimming animals, but salpae will easily endure such damage of colonies: they have an ability of fast regeneration.
Giant sluggish fishes draw the shark cub’s attention, and it slightly pushes one of them by snout. In reply to such behavior sea wyvern has tried to frighten a stranger off: the fish began “color play”, turning in rotation either pale blue, or spotty. After several seconds of color fireworks the fish became striped, of black-and-white color. Black strips on a sea wyvern’s body have begun to extend gradually, and the fish has turned entirely black. Other fishes around have also begun to darken, having noticed that one of their relatives has got such color. Their “show” was not limited to this trick. Sea wyverns are able to produce sounds as good as shovel croakers. However, their “repertoire” is limited to loud clicks and coontinuous hissing. All sea wyverns surrounding the shark juvenile began to utter such hissing at once. This sound has stopped cachalot shark cub for a certain time, but famine has got the best of fear, and shark cub attacked the nearest “dragon” resolutely. Its teeth have literally squeaked against bone armour of sea wyvern, and replying to it the attacked fish has emitted a jet of fetid ink in water. Acute pain has burned nostrils of young cachalot shark – very keen sense of smell does not endure a smell of the fetid liquid produced by sea wyvern. Wyvers, mythical dragon believed to be a distributor of plague, and its sea-dwelling embodiment appeared adequately to its prototype. Having let off sea wyvern, the unlucky hunter has rushed away. Due to such chemical weapon sea wyverns can not be afraid of attacks even of adult cachalot sharks: having met closely these fishes for some times, sharks do not disturb them and the memory of such meeting is kept at them till the whole life.
Shovel croakers, usually being noisy, stop their songs and move aside respectfully, when young cachalot shark swims through their school. These fishes are too fast for shark to catch them, but nevertheless they behave reasonably when keep aside even young sharks.
After several hours of wanderings in the ocean the cachalot shark juvenile noticed a silhouette of an oblong creature floating in thickness of water. Young shark had never seen before an orca squid, but if it will be lucky enough to grow up, these animals will diversify its diet. The shark cub’s brain is too small, and it lacks any life experience absolutely, and it hardly guesses the danger these animals represent for it. Squids of this species sometimes attack even newborn sharks, especially weaker ones. But this mollusc is inactive for some reason, though young shark looking rather tempting moves directly to it. The mollusc hovers in thickness of water, from time to time moving its arms and watching by one eye for movements of shark juvenile. The meeting with sea wyverns has taught the young predator not to hasten to attack, therefore now it behaves very cautiously. But the orca squid does not undertake any reciprocal actions in relation to young shark, and the fish decides to examine this monster a little bit closer. If the young shark would have an experience of meetings with orca squids, it would understand that the animal is not in the best physical shape: mollusc’s skin is wrinkled, eyes seem slightly sunk down in eye-sockets of gristly head capsule and fins are wrinkled and slightly frayed along the edges. Shark juvenile swims near the motionless orca squid, almost touching its sides, and only now the mollusc reacts to it: the squid emits a small portion of ink and swims aside. Having learned through hard experience, young shark swims far away from ink cloud curling in water, and leaves orca squid. The strange condition of this cephalopod has a very simple reason: it is a female, which bears posterity, and it is ready to give birth to young animals within next some hours. In other time a real danger would threaten the young shark from this mollusc, but not this time. At this squid species large eggs develop in mantle cavity, and embryos get feeding from a parent organism: eggs adhere to the wall of mantle cavity. The result of it is exhaustion and slackness of the mollusc – it is a final stage of female’s life cycle. The posterity began to develop roughly, and the parent organism transfers its last resources to new generation. Female’s life is finished all the same, and the most expedient action for the species as a whole is to minimize an amount of nutrients passing to the stomaches of sea scavengers.
In some hours completely exhausted orca squid female begins to give birth to posterity. The young squids reached almost half-meter length during the female’s pregnancy begin to leave her mantle cavity one by one. Some of them still carry on their bodies the rests of egg shells, but remove it soon, moving their fins. Like shark juveniles, they live by themselves since the first minutes of their life. However, nobody will take care to them all the same: in some hours after all of them will swim away, the female will perish. The destiny of all cephalopods is those – to breed once in life, and to die then. The corpse of orca squid female will be quickly eaten by scavengers of various kinds. It is possible, that it will be eaten even by jumping squids hunted earlier by this predator. But also those squids that were born some hours ago, will manage to grow up and to die before the newborn cachalot shark which has swam near their mother will grow up to half of the length of adult fishes of this species. It is possible, that short life of squids prevented them to become the true lords of the seas of the Earth. And the life of cachalot shark represents many tens years of regal greatness at the top of the food chain of the ocean.

Cachalot shark (Physelache planicephala)
Order: Squaliformes (Squaliformes)
Family: Giant sharks (Cetoselachidae)
Habitat: Atlantic, depths 100-500 meters.

Continents of the Earth constantly move, and many things depend on their movement, including the pattern and the direction of ocean currents. And currents influence directly to the existence of plankton and to the overall productivity of various areas of World Ocean.
At the end of Holocene and in early Neocene the mass extinction of sea mammals had taken place. Their populations undermined by human activity and ocean pollution appeared unable to restore in conditions of geological and ecological cataclysms, and have gradually died out. Subsequently at the stabilization of conditions in biosphere and the improvement of life conditions various species of another sea-dwelling animals have began to occupy their place in nature.
The largest of hunters of depths in Holocene epoch was sperm whale (Physeter macrocephalus). Though it was inextricably connected with water surface in its life, fodder areas of this whale stretched at the great depths, outside of zone of reach of the majority of animals comparable to it in size. In Neocene seas one representative of sharks – cachalot shark leading the similar way of life – has occupied its ecological niche.
It is one of the largest fishes of Neocene: the overall length of its body is up to 25 meters. Large flat head makes about a quarter of the total length, and an oblong tail fin with very long top blade positioned almost horizontally is of approximately the same length. Pectoral fins of cachalot shark are wide and long, and look like wings. Their bases are shifted upwards, to the middle line of the body, having pressed gill slits a little bit downwards. There are two dorsal fins: the first one is located at the middle of body length, is triangular and carries a rudiment of the spike characteristic for ancestors of the present species, small dogfishes (Squalus); the second dorsal fin is short and very reduced, stretching almost from the basis of the first dorsal fin up to the beginning of tail.
In rest this fish swims slowly due to coiled bends of the body, but during the prey chasing it can accelerate movement with the help of flaps of pectoral fins. For keeping of buoyancy it has a liver rich in fat and liver making up to 1/3 of the total weight of the fish. Thick skin of this shark is covered with small bone plaques protecting it from attacks of all possible underwater predators. Of course, large predators able to kill such fish are not present in the ocean, but there is a mass of smaller animals which feed by cutting pieces of skin and muscles from large fishes, or simply parasitize on bodies of sea giants. The rough surface of skin of cachalot shark partly interferes with their activity.
This fish is colored rather modestly: it has one-colour dark brown back and yellowish belly. For the fish spending the most part of time in twilight of ocean depths bright colouring is not as important, as for shallow water fishes: this solitary creature seldom communicates with its congeners. For this purpose it uses not rather weak sight sense, but other, more advanced senses.
For hunting its main prey – giant pelagic molluscs – this species of sharks has surprising “secret weapon”: very keen sense of smell. Huge slit-like nostrils of this species reach almost one-meter length. They are opened only on both ends, but are closed on the most part of length; therefore they actually represent not simple olfactory sacs, but true pipes through which at the movement of this fish a direct water flow takes place. An olfactory surface inside these surprising nostrils is folded and forms a set of longitudinal plicae. Sense of smell of cachalot shark is very sharp: it feels literally some milligrams of the odorous substance dissolved in one ton of seawater.
The main prey of cachalot shark includes giant pelagic cephalopods and swimming gastropods keeping in thickness of water, and dead large fishes. It is rather soft prey, therefore teeth at the present sharks species differ a lot from usual “shark” stereotype: these are not cutting edges, but rather short stabbing points arranged in jaws in several rows. Their main function is not to cut to pieces, but simply to keep slippery, but very weakly resisting prey. Jaws of this shark can move forward a little due to elastic ligaments and to open wide. When at the majority of sharks mouth is inferior, at this species it is shifted forward, and snout is very short.
Eyes of cachalot shark are very small, located on sides of the head. Sight sense is very weak, and this fish receives the most part of the information on the world around by means of sense of smell and excellently advanced electric feeling. The skin on head is covered with the advanced network of electroreceptors detecting the slightest electric activity of live creatures near this giant shark.
Small shark species breed via vivipary or lay large eggs, but this shark has completely passed to true vivipary. During approximately 20 months after the copulation in ovoducts of cachalot shark female two large juveniles develop; body length of a newborn shark of this species is about five meters. Juvenile is born completely ready to independent life. It breaks a membrane surrounded it at the moment of birth, which frequently becomes its first meal in life. Young cachalot sharks feed mainly on fish: they are more mobile, than adults, and can hunt faster and smaller prey.
Cachalot shark lives in open ocean at the depth of 100-500 meters, but can rise to the surface at night, especially in colder waters. Then it is possible to see how giant backs of these giants appear at the surface of the sea, shining in moonlight. They may be misidentified as whales, but they do not utter sounds characteristic for these animals – noise from their breath. Vertical migrations of this species are connected to migrations of prey – large molluscs eating planktonic inhabitants.
This shark does not make distant migrations, and avoids too warm waters. This species has formed two rather separated populations in temperate zones of Atlantic in both hemispheres. There is a contact between them: separate “tramps” frequently cross equatorial zone of Atlantic via deep waters. Nevertheless, separate sharks can occasionally penetrate via Panama Strait into Pacific Ocean, but a viable population of this species had not established there.

Shovel croaker (Brevisciaena argentea)
Order: Percoid fishes (Perciformes)
Family: Croakers (Sciaenidae)
Habitat: Atlantic, subtropical zone, comes into temperate waters in summer.

Natural catastrophes at the boundary of Holocene and Neocene had adverse consequences in natural communities. Some of them came in decline, and some could not restore at all.
Sharp change of life conditions had adversely affected the natural communities of open ocean. The plankton, a basis of food chain, has seriously suffered during natural cataclysms. Some organisms maked its structure had died out completely, and the number of other ones had drastically decreased. Accordingly, all species of animals dependent on it had seriously suffered. All species of cetaceans and the most part of species of oceanic pelagic fishes – mackerels, tunas, swordfishes and others – had become extinct. In Neocene their place had been substituted by other kinds of animals, descendants of inhabitants of coastal zone or shallow seas rather independent of planktonic productivity of the ocean. Among these animals there were various fishes, including croakers well-known for their “musical” abilities.
Shovel croaker is one of true pelagic croaker species. It is a large schooling fish: the length of an adult individual reaches half-meter, and even more. The fish has all main qualities of the inhabitant of thickness of water. Body of shovel croaker is silvery-blue, short and deep. Tail fin is crescent. Head has a prominent forehead; males have additional fat cap increased in courtship season. During the spawning male gets the courtship dress: its head becomes almost black with silvery spots on the operculums.
Like all related species, shovel croakers have ability to produce sounds using swimming bladder. Males in courtship season are especially “vociferous”.
These croakers are typical predators. Their diet includes molluscs (even young squids), small fish and large planktonic animals.
One more circumstance promoted the development of pelagic lifestyle by croakers is their breeding mode. Croakers spawn pelagic eggs, not caring of posterity at all. At shovel croaker spawning takes place in schools, and fertility reaches 200 thousand small eggs. Fishes spawn by the whole school simultaneously, producing simultaneously a full portion of eggs and soft roe. In 2 days transparent larvae hatch from eggs. At the age of about one month the few survived ones turn to fry up to 2 cm long similar to adult fishes by body shape. At one-year-old age these fishes grow up to 10 cm and form schools. At this age they have a pattern of longitudinal strips preventing any predator to distinguish a separate fish in school. Being lucky enough to survive, in 2 years they will reach the length of about 40 cm, will lose juvenile striped colouring and can take part in spawning.

Sea wyvern (Vivernocampus titan)
Order: Syngnathiforms (Syngnathiformes)
Family: Pelagiс seahorses (Pelagocampidae)
Habitat: Atlantic Ocean, top layers of water.

After the mass extinction, the evolution of some groups of live organisms can change its direction completely, if there is an opportunity to develop a whole new ecological niche. It appeared so in Neocene with the representatives of seahorses. The overall number of these harmless plankton eaters decreased drastically because of falling of the productivity of ecosystems. Only few species from the number of the most unpretentious ones have managed to survive. In early Neocene, when a plenty of free ecological niches has appeared, one of their kinds began the development of the habitat unusual to these sluggish fishes – the thickness of ocean waters far from the coast. This step was promoted by the sharp increase of the abundance of the plankton, which has taken place at this time, and was caused by absence of any effective plankton devourers.
Pelagic descendant of seahorses has turned to a wonderful creature, becoming the largest representative of this group of fishes. For its “dragon-like” appearance it is named as “sea wyvern” (wyvern is one variety of mythical dragons). The length of this fish reaches 5 meters, from which tale makes about three meters, and almost one meter more is a length of head decorated with freakish outgrowths.
Body of sea wyvern is covered with hard bone plates forming the armour protecting this fish from an attack of various kinds of predators. Pectoral fins have powerful muscled bases and are the main propelling organs of this fish. Flapping them like wings, sea wyvern moves in thickness of water.
Maintenance of buoyancy of this heavily armored fish is promoted much by its ability to to acquire fat rapidly and to stock it in large liver, which is stretched along the body approximately from the basis of pectoral fins up to the middle of the tail. Due to it, the body of fish has almost zero buoyancy, and the fish easily moves in water. The back fin stretches along the whole trunk. Its wavy movements help this fish to swim forward. In case of need to swim faster, the fish can move by coiling the whole body.
Body colouring of sea wyvern changes in very wide limits: the ability to change colouring characteristic for seahorses has got the further development at this species. While at seahorse change of colouring takes some days, sea wyvern is as skilful in it as an octopus or a squid. Its fins can change a transparency only, but the body gets colouring from silver-gray up to cherry-red depending on the need of the fish. Usual colouring of this fish is grey with dark spots making a chaotic pattern and merging on tail to longitudinal lines.
Colouring helps this creature to mask, escaping from sea predators. But in addition to it sea wyvern protects itself against enemies by emitting an unpleasantly smelling black liquid. Its meat is also unpalatable, and the majority of fishes of this species perishes from casual predators. But the adult sea wyvern has actually no predators.
Head of sea wyvern has very freakish shape: it is tube-like; above large eyes of a fish “horns” stick, and along the muzzle a crest of warty outgrowths stretches. Mouth is small, located on the tip of tubular snout. The fish feeds, pumping water continuously through its mouth with the help of pulsing movements of throat and filtering plankton by gills. However, in a considerable part of diet of sea wyvern is made of aquatic invertebrates – jellyfishes, salpas and larvae of pelagic molluscs. Even the poison does not protect jellyfishes from this animal – sea wyvern devours them right with tentacles. After breeding of tiny herring squids, when molluscs perish in huge amounts, sea wyverns willingly “graze” at their breeding places, devouring both dead squids and their eggs.
Sea wyvern breeds, keeping the “traditions” of its ancestors. Female lays very large eggs into the special brooding pouch on male’s belly. The amount of eggs in one clutch makes only 50-60 ones of size of chicken egg. They adhere to walls of male’s brooding chamber and receive feeding from male’s blood. Egg incubation lasts till about three months. Due to such feature of breeding newborn sea wyverns are very large (about 30 cm long) and at once belong to the number of the main plankton predators. They grow slowly, and reach the lengths of three meters only at the age of ten years. At that time they turn able to breed for the first time. They reach the maximal size at the age of about fifteen years. However, life expectancy of sea wyvern makes about 50-60 years.

Jumping squid (Delphinotheutis malandrinus)
Order: Squids (Teuthida)
Family: Neololigids (Neololigigae)
Habitat: Atlantic Ocean, superficial waters.

Picture by Tim Morris, colorization by Biolog

After “planktonic catastrophe” of the border of Holocene and Neocene the majority of oceanic fishes had simply died out. Certainly, new kinds of fishes, descendants of the ones lived in coastal waters, came to replace them. But of this situation cephalopods – the main competitors of fishes – also had taken an advantage. They have occupied some habitats, having turned to worthy contenders (and sometimes to terrible enemies) of fishes.
One jem of “design ideas” of nature is the jumping squid, which lives near the surface of the ocean. It is active nekton predator, which had partly occupied an ecological niche of smaller cetaceans, of dolphins. Body length of this mollusc is up to one and a half meters, arms are about half meter long. Body of jumping squid is tight and muscled. The basic bodies of movement at this species are strong and long fins of triangular shape. The fin-moving muscles are attached to wide shield-like gladius (corneous plate, a shell rudiment), on which the crest is also developed; gladius of this species looks similar to bird’s keel bone overturned and stretched in width. Such development of the structure reduced earlier is connected to changes of the body size of this animal. Jumping squid is one of fastest speedsters of Neocene Atlantic Ocean: it can accelerate momentum up to 50 kms/þ, and even up to 70 kms/þ at short distances. To speed up its movement, this squid even can jump from water like a dolphin. Sometimes it makes jumps up to 4-5 meters long.
Body of jumping squid is colored grayish-blue with small silvery spots. Due to such pattern it is difficult for noticing both to predator and prey. If necessary, this animal can change background color from white up to almost black or crimson, and expand silvery spots to form a uniform shining background.
Similarly to all cephalopods, it is a predator (a specific epithet “malandrinus” means “pirate”) hunting fish and smaller squids. It keeps in small schools (of 5-6 individuals), and even arranges co-ordinated collective hunting for fish or small squids. This animal has developed the special adaptation for hunting. Ink of all cephalopods used for self-defense is poisonous. At this species, ink is almost colorless, but had turned to poison for smaller fish: having surrounded a school of fishes, squids simply poison them, and then gather and eat. In due course of evolution, these squids have one more valuable property, immunity to their own poison, that enables them not to wait while the poisonous cloud will dissolve. Also the poisonous liquid is used for protection: squid emits it, escaping from the predator’s chase.
Jumping squid lives in open ocean, and does not dive to great depth: usually this species may be found at the depth up to 50 meters. For breeding it prefers rocky shelf, where numerous schools of these animals gather. During the courtship games males get very bright colouring: red longitudinal irregular-shaped strips. Courtship games take place at the surface of ocean, where males jump out of water and try to impress females with the brightness of their colors. When the pair of animals is formed, both partners darken and dive to the bottom. After copulation males die, and females find a place for the clutch. Usually they paste egg sacs to slopes of underwater mountains, and then, having emptied the ovaries, also quickly degrade and perish. Their bodies sink to depth, where become a food for various animals.
The posterity of this species lives in plankton, forming numerous congestions. Life expectancy is about five years.

Orca squid (Orcinotheutis vorax)
Order: Squids (Teuthida)
Family: Viviparous squids (Viviparotheutidae)
Habitat: Atlantic Ocean, top layers of water.

Picture by Tim Morris, colorization by Alexander Smyslov

According the fossil data, shells of prehistoric cephalopods could reach the monstrous size, up to 4-5 meters long. Giant squids (Architheutis) known to people could be monsters of 18-meter length. But ancient giants have died out without any descendants, and Architheutis squids had met the same fate as many deepwater species died out in epoch of mass extinction. But in Atlantic Ocean of Neocene epoch their successor – large orca squid – has appeared.
Giant Architheutis squid was sluggish and languid creature, and its body had rather flabby consistence. As against it Neocene orca squid is an active solitary predator, though occasionally it can eat carrion. It is smaller compared to its Holocene cousin, reaching the total length of about 4 meters including arms. It has large eyes, and arms make up to half of total body length. Its skin colored light pink with brownish nerves; the top side of its body is speckled with dark spots.
But the most basic difference of this squid from the giant of Holocene epoch is the development of its muscles. The main propulsion organ of orca squid is the advanced jet device. Ring muscles of the mantle are well advanced, and supply with blood actively. They have literally tightened mollusc’s body in elastic corset. Inside muscles even elastic gristly half rings are developed, supporting the body shape and helping to fill the mantle cavity with water automatically at the relaxation of muscles. Fins of this species function mainly as rudders and stabilizers at movement. They are rather long and rather narrow, of crescent shape. Only occasionally at slow swimming this squid uses them for rowing. The additional structure raising the buoyancy is a huge liver, in which easy fat is stocked. Having this attribute, the squid has convergent similarity to sharks.
Orca squid justifies its name by the character of its feeding: it hunts large squids of other species and fishes. Having an effective weapon for an attack, it hunts even juveniles of cachalot shark.
The main hunting weapon represents very strong jaws. “Beak” characteristic for cephalopods is additionally reinforced with lime deposits and can crack even bones of large fishes. Bite of orca squid is poisonous: salivary glands are modified and enlarged, producing strong neuroparalytic poison (parallelism with the octopuses also having poisonous bite is observed in it).
Orca squid is adapted to pelagic habit of life, and never comes close to the coast. Due to an active way of life this species requires a plenty of oxygen, therefore avoids areas with stagnant and heated water, and also does not dive in depth.
Features of breeding enable this species to lead such way of life. If in human epoch squids of usual kinds swam up to the coast for egg laying, this species has completely lost these features of behaviour. It also has avoided necessity to lay numerous tiny eggs, leaving defenceless posterity to the mercy of fate. Orca squid is unique among Neocenew cephalopods in being actually “viviparous” species: female bears very large eggs (up to 100-150 ones) in its mantle cavity. Each egg has soft shell, which sprouts into the wall of mollusc’s mantle with fibers, and the embryo receives nutrition and oxygen directly from mother’s blood. At this time blood vessels of the female bearing young growth sprout into the internal layer of its mantle. Uring the incubation in female’s organism irreversible physiological changes take place: it becomes inactive and does not eat, living only due to the accumulated stock of fat. The only thing female can do is to protect its posterity with the help of poisonous bites. After three to four months of incubation female loses flesh, its muscle tissues degenerate, and almost right after birth of juveniles it perishes. Young squids are very large, up to 40 cm long. Leaving female’s mantle cavity, they are at once ready to independent life, and their bite is poisonous. Death rate of posterity of orca squids is very low. Life expectancy is about eight years.

Crystal squid (Pellucitheutis crystallinus)
Order: Squids (Teuthida)
Family: Crystal squids (Crystallotheutidae)
Habitat: Atlantic Ocean, top layers of water.

Picture by Amplion

The mainstream in evolution of cephalopods during their history was pelagization – the adaptation to life in thickness of water. Representatives of squid order have especially succeeded in it. Among different families they repeatedly and independently from each other evolved the forms adapted to life in in thickness of water. The significant part of them has died out in time of “planktonic catastrophe” at the border of Holocene and Neocene, but after the restoration of conditions favorable for life active speciation began among coastal squids. Literally in the first some millions years of Neocene epoch true pelagic squids of new generation have evolved, and among them there were remarkable delicate creatures – crystal squids.
The present species of cephalopods is a typical planktonic squid never living near to coast. Crystal squid has almost transparent body up to 15 cm long; arms make approximately one third of total length. Also it has a pair of hunting tentacles extending up to half meter. Hovering in thickness of water is provided by wide transparent fins, which, however, are too weak to enable this animal to resist to ocean currents.
It is a schooling species of cephalopods; its school may number up to several hundreds of animals. In daytime these squids are almost invisible in thickness of water – only their eyes from time to time sparkle in sunrays, giving out the presence of these molluscs. However, at night from invisible beings these squids turn to wonderfully bright creatures: they have light organs. The whole body of crystal squid is covered with small photophores, and at edges of fins they are very large. Photophores shine blue on the body, and bright yellowish-white light on fins. This mollusc shines only at night, and brightly flashes at fright. In daytime crystal squid does not shine, masking itself from predators: transparency is its only protection; in order to achieve this result, at this squid even the ink sac has disappeared.
Being a pelagic creature, crystal squid breeds, attaching its eggs to floating brown algae. Separate islets of these plants float in the middle of Atlantic, in the whirlpool formed by several currents: Panama (directed to Pacific Ocean), Antigulf Stream (flowing along the coast of Europe) and Gulf Stream. Female can keep eggs in oviducts for rather long time, until it will find suitable substratum for its clutch. After egg laying female’s organism degenerates very quickly, and it perishes within several hours.

Sticky skin squid (Echeneotheutis semiparasiticus)
Order: Squids (Teuthida)
Family: Sucker squids (Parasitheutidae)
Habitat: Atlantic Ocean, bodies of large cachalot sharks.

In Holocene epoch all cephalopods were active swimming predators. But in Neocene, when biosphere had been literally “shaken up” from top to bottom, and former connections between live creatures were interrupted, some representatives of cephalopods began to evolve to very unusual forms and to develop ways of life atypical for them earlier. For example, at the reeves of Pacific Ocean, strange octopuses digging holes or leading fully sedentary habit of life like polyps have evolved. In Atlantic one squid has turned from actively swimming creature to almost sponger species.
Sticky skin squid is a commensal of giant fish – cachalot shark. It spends almost the whole life, except for the earliest part of life cycle, being attached to skin of this fish. The shark receives obvious benefit of presence of this mollusc: it clears shark’s skin of parasites. The length of sticky skin squid is almost one meter, and arms make about one third of total length. Its skin is covered with lumps and can change coloration from brown up to yellow depending on the site of shark’s skin the mollusc is attached. The texture of skin of this squid successfully imitates shark’s skin, and while the squid is motionless, it may seem that it is a kind of outgrowth on skin of fish.
It is not so easy to keep on skin of moving fish, even if skin is rather rough. For this reason, the body of sticky skin squid has appreciablly changed in comparison with free-swimming relatives. Fins at this species became thick and muscled, having actually turned to suckers. Their bottom side has the deepenings surrounded with rings of elastic tissue. For increase of coupling edges of fins of this squid are supplied with a fringe of corneous bristles. The body of this mollusk is flat, on its bottom side there are two longitudinal rows of sucker pits. Sticky skin squid can retract its head under mantle completely, when shark moves. Along the edge of its mantle there is a ring muscle which stretches edges of mantle like an elastic band, leaving only arms outside. It enables this squid to keep easier in the stream of water flowing around the body of swimming host shark.
The beak characteristic for cephalopod molluscs has turned to a grater at this squid: lower jaw became flat and wedge-shaped. Upper jaw is overgrown with soft tissues from sides, and the mouth is shifted downwards. It is very convenient to scrape away sedentary animals from host’s skin using such beak. Eyes of sticky skin squid are rather small.
Arms are very short and wide; there are two lines of strong suckers on them. Hunting tentacles are supplied with corneous “razor blades” (modified corneous hooks typical for squids), with which help these molluscs cut off sedentary animals from skin of cachalot shark. Tentacles can extend forward to approximately half-meter. An additional food source at this mollusc is the rests of shark’s meal. When the fish tears its prey, squids creep closer to its head, extend tentacles and start begin moving them, grasping scraps of meat floating in water.
Adult mollusc is almost unable to swim; it can only creep on body of shark. Usually on the body of any separate shark some such squids keep, keeping the cleanliness of its skin. Squids also breed on shark’s body. If the animal does not find a breeding partner, it can swim to the body of another shark, but only if fishes appear very close to each other. Sticky skin squid swims very clumsily and slowly, using their fins only. Having reached up to a new shark, squid seizes its skin by tentacles, tightens its arms, and then sticks with its whole body. It as if repeats an evolutionary way of its ancestors: from animals, that only casually search for food on skins of giant sharks to ones staying on fish’s body for more or less longer time, and finally to completely sedentary forms.
Because of such dependent way of life at sticky skin squid one feature of physiology had developed – this mollusc can endure sharp pressure differences. It survives, when the shark quickly moves between surface of water and depths, or when it jumps out in air and falls in water.
This squid breeds once per life. Like the majority of its relatives, it lays eggs, and attaches it clutches to shark’s skin. Female lays up to 20 egg capsules, each of them contains 2-2.5 thousand eggs. After breeding adult squids perish. Clutches are in relative safety though young sticky skin squids can occasionally damage them. Juveniles hatch 15-20 days later. Larva swims actively in thickness of water and leads a predatory lifestyle usual for squid. It has normally advanced eyes. Juveniles grown to the length of 10-15 cm search for cachalot sharks and settle on their bodies, staying on them for almost all further life. After the young squid settles on shark’s body, its fast metamorphosis begins, and its body gets outlines of adult one. Life expectancy of this species is about three years.

Sea ghost (Phantomohelix mirabilis)
Order: Xenopteropods (Xenopteropoda)
Family: Fin snails (Pterohelicidae)
Habitat: Atlantic Ocean, eastern areas of Pacific Ocean; from the surface up to depth of 100 meters; it lives in tropical and temperate zones, but in summer separate individuals may be met much farther to the north and to the south of the basic area of this species.

In Holocene among gastropod molluscs there was a distinct group of swimming planktonic organisms – pteropods (Pteropoda). These animals had substantially lost the appearance characteristic for the majority of gastropods: their shell is partly or completely reduced, and the foot has formed wide fins with which help these animals moved actively in thickness of water. These animals bred in great amounts, and their reduced shells accumulated at the sea bottom, and even formed special kind of sediments – pteropod ooze.
Mass extinction has destroyed a significant part of planktonic organisms. Among the dyed out forms there were actually all pteropods. But in Neocene gastropods have made the second successful attempt to develop open ocean. And this time they have developed a new size class, and a new way of life of an active predator hunting large prey.
Sea ghost is a representative of new group of pelagic gastropods. In its shape this animal is similar to a strange mix of bird and jellyfish. Total length of sea ghost is about one meter. Body of this animal is translucent, whitish and of rather gentle consistence: in fact, sea ghost is a large planktonic organism. Shell is reduced up to a thin corneous capsule (the calcariferous layer is completely reduced), and it is too small to contain the body of this animal. But it has turned to a part of the effective respiratory device. Its walls due to their elasticity support branchial cavity of this mollusc in opened condition. From below the branchial cavity is bordered by gristly plate. Plate and shell are connected on edges with powerful cross muscles, which at the contraction press them to each other, reducing volume of branchial cavity and eject water from it. At the relaxation of these muscles the volume of branchial cavity increases due to elasticity of its walls – the mollusc “inhales”. Mantle forms two valves: incurrent one (through which “inhalation” takes place) is turned forward, and excurrent one is directed back.
To gristly basis of respiratory cavity internal bodies of mollusc are attached.
Foot of sea ghost is modified in radical way: now it has not a function of crawling at all. Astarotus (Astarotus diabolicus) from Caribbean Sea related to sea ghost has kept ability to crawl, but sea ghost lives exclusively in thickness of water, not coming nearer to coast. Foot of sea ghost in its forward part is divided into two strong wing-like fins, its back part represents long “tail” – a balance organ having at the bottom edge extended keel of dense and gristly consistence. The muscles of fins are attached to the rudiment of the shell and to gristly plate. During its whole life sea ghost slowly swims in thickness of water, flapping its fins like ray.
Despite of apparent fragility, sea ghost is a gluttonous predator well equipped for hunting other planktonic animals. It has large eyes about 3 cm in diameter located on tips of long tentacles. This mollusc can distinguish colors, and is especially sensitive to movement of subjects. Brain of sea ghost represents a large nerve ganglion visible in thickness of head tissues. This mollusc is rather clever, though is very far from marvellous intelligence of cephalopods.
Mouth of sea ghost is extended to trunk, inside which it is possible to notice back and forth movement of short radula of this mollusc. Near the mouth a pair of short tentacles grows – these are organs of chemical feeling.
Sea ghost eats small planktonic organisms and due to it this one evolved the interesting mechanism of getting of food. On each side of head it is possible to notice large inflated “cheeks” – these are well advanced salivary glands of a mollusc, secreting saliva of several types depending on circumstances. “Hunting” saliva at this species is sticky. Hungry sea ghost emits from its mouth pastelike strings of saliva, which is strongly swelling in water, and waits, while prey will paste to them. Thus the animal keeps an edge of slimy “cloud” in mouth in order to save its dinner. When the enough number of tiny planktonic organisms pastes to slime, animal simply eats slimy trap with prey. However, this mollusc also does not disdain to eat carrion, feeding on dead fishes, squids and other animals.
Another kind of the saliva produced by sea ghost is “battle” saliva. This mollusc protects itself against predatory fishes, splashing to them a jet of sticky slime having toxic properties: this slime paralyses olfactory nerves for some time and causes temporary blindness in fishes attacking this mollusc. However, such protection is effective only against medium-sized fishes. “Battle” saliva may be used for hunting only in one case: when the mollusc attacks poisonous jellyfishes. It simply emits mix of “hunting” and “battle” saliva on their burning tentacles, and then eats the paralysed prey without difficulties.
Sea ghost is a hermaphrodite that considerably facilitates search of breeding partner for it. Eggs develop quickly and in portions, therefore in the ocean it is possible to find the molluscs ready to breeding, and also clutches and larvae in every season. Having met each other, molluscs first define each other’s readiness to copulation. If pairing is possible, they swim closer to the partner by the right side (from this side mantle plica passes), and mutually fertilize each other. Pairing lasts for some minutes only. It is an only time when it is possible to see two molluscs together: usually they live solitarily, and only in areas rich in forage it is possible to see several sea ghosts at once. However, each animal leads the independent life, perceiving its congeners only as an annoying obstacle in life outside of time of readiness for pairing.
These molluscs breed by egg laying. Clutch representing a slimy translucent cocoon may contain some hundred thousand small eggs. Perhaps, the time of egg laying is an only moment, when this kind of molluscs requires any firm objects available: sea ghost pastes its clutch looking like a bottle with short neck on floating subjects and abandons it. “Cradle” for new generation of sea ghosts may be tree branch, coconut or any other floating dust. During volcanic eruptions in the sea there are pieces of pumice, which serves as an ideal substratum for clutches of these molluscs. Sea ghost makes one such clutch on average once in two weeks.
Development of the clutch lasts about one week. Larvae hatched from eggs gradually eat the slime surrounding them, and the clutch falls apart. Larva of sea ghost is not similar to an adult mollusc: it has short cap-like shell, and its foot is divided into four wide blades serving as fins. It hovers in thickness of water, eating small planktonic organisms. The significant amount of such larvae falls prey of adult molluscs of the same species. After about one month larva undergoes metamorphosis and turns to a tiny copy of an adult mollusc. Thus at young sea ghost the special feature develops, which interfers its falling into traps made by adult animals: one part of salivary gland secrets a substance neutralizing and dissolving sticky slime of adult animals.
Sea ghost grows slowly at first: at three-monthly age the animal reaches the length of about 20 cm, and further its growth is considerably accelerated – the animal enters a category of predators. Half year old mollusc is about 70 cm long and already can breed; general life expectancy at this pecies may reach three years.