Returning to the Water

In a world as wet as hothouse Serina, that some land animals - perhaps already made to swim through flooded landscapes inland - would evolve to return to the oceans was inevitable. Land-living creatures becoming secondarily aquatic is a constant throughout evolutionary history, not only on Serina but long before it, too. Yet the ways different animals come to make a living from the water are many and varied. Below, we will meet five different animals, three from very different avian lineages and two from the tribbethere side, and explore how each one of them has adapted to meet the challenges and access the riches that the water can bring.

The first animals on our list to meet are the whelicans, a group of almost completely aquatic birds of the middle hothouse, 285 million years PE, which have evolved from squelicans. These scroungers now spend nearly their whole lives in water, where they hunt fish and crustaceans via suction into their expansive throat pouch and eject the resulting seawater, seining out the food. Whelicans can no longer walk, their legs being too splayed and far back on the body, though can still haul out on land to rest and push themselves onto rocks or sandy beaches by sliding on their bellies, and may do so occasionally. A few of the most derived species no longer need to come on land even to breed, for they have learned to hold their delicate egg within their mouth and nestle it into the pouch where it can be kept warm, even as the parent becomes too large and ungainly to brood it beneath the body. Just as a similar behavior did in the ancient and unrelated pelecanaries and their descendants the birdwhales, this innovative new way of incubation has allowed these birds to become bigger and to truly start to abandon their final tie to the land. 

Whelicans are a varied group of animals, still diversifying rapidly as they spread across the world via the oceans, and different species are already specializing toward a variety of diets. Some are active predators of larger fish and catch them with hooked tentacles, using the pouches to store food to take it home to a waiting mate and chick. Others are filter feeders, sucking in schools of baitfish or shrimp like a whale and filtering it out through a baleen-like net of bristles lining the interior surface of their tentacles. The sniper whelican however must be the most remarkable of all, for it alone has learned to bring down prey from the realm above the waves; it is a predator of birds and small tree-dwelling animals, which it targets not from the open ocean but the brackish waterways of Serinaustra's saltswamp. 

To catch them in a domain it is unable to enter itself, it makes use of a clever trick that it equal parts evolutionary marvel and practiced skill: it fills its pouch with water and then brings its tentacles together tightly to form a narrow tube through which it forces the water out, creating a powerful pressurized water jet that can extend more than 15 feet, which it uses to knock unsuspecting animals flying or climbing above down into the water for it to snatch up. Most of its targets are small birds and large bugs, but by working in a group to disorient prey and not give it a break between jets, the sniper can sometimes even knock animals as large as monkey-like scamps into the water, and then share the kill among themselves. For an animal weighing some 150 lbs, bugs and songbirds just don't always suffice. 

If the trees don't bring a full belly, snipers are still generalists and will hunt for aquatic prey, targeting fish in the narrow channels of the swamp and trying to corner them against tangles of roots. They may also leap out of the water, propelled by their large, lobed flippers, and snatch low-hanging victims directly from their perches in its jaws.

Not all who swim are hunters, and some are much more peaceful in their natures. In the seagrass meadows along the sunlit coastal shelf of Serinaustra, a herd of dolfinches graze placidly. They have been in the water much longer than the whelicans, their ancestors returning their in the early Pangeacene. Yet they, too, were once land dwelling birds. Now they are slow and sedate, plump and playful, cavorting in the clear, sunlit waters with slow circling movements over the sea floor and between the long, willowy blades of the puffgrass that dance in the gentle current with a life of their own. Their colors are the first thing that stands out, for unlike most of their relatives these creatures contrast boldly against the backdrop even from a distance, their smooth skin patterned intricately in bands and blotches of black, white, gold and amber. They make no effort to conceal themselves or hide among the greens. They appear entirely harmless, but beware: they are nocuous perilporps, and they know they have nothing to fear, for even in a sea full of monsters and beasts, they themselves are one of the deadliest of all its living things, and not a single one dares to touch them. 

Perilporps are a group of dolfinches evolved from porpedos that sequester deadly tetrodotoxins from a diet that includes a wide range of marine algae and certain shellfish, and store them in all of their body tissues, but especially their skin and internal organs. This neurotoxin is produced by a variety of bacteria, many of which are common in the muddy sea sediments that their food sources dwell. The organisms that they feed on have usually evolved to store this toxin to defend themselves against against smaller predators, with the quantity they hold in their tissues insignificant to large animals that eat them and usually metabolized out of the body without building up. Yet the perilporp stores them internally, initially rendering it merely unpalatable to the large sea-going snarks, and so improving its survival incrementally so that over millions of years the perilporps have evolved total immunity to the normally paralyzing effects of the poison even in the extreme concentrations it now carries. While this deadly weapon is acquired via the diets of adults, mothers pass it on to their embryos in utero through placental ties so that even their newborns come out pumped up with enough tetrodotoxin in their bodies to kill a predator over fifty times its size.

Because perilporps are so toxic, they have nothing to fear from even the most formidable marine predators, and their behavior reflects this. Because they are invincibly protected, they have lost almost all fear responses typical of animals as small as themselves and will even approach apex predators with curiosity, usually being ignored entirely - sometimes a naive young calacarna will make a test bite and immediately release them, even a slight breaking of the perilporp's skin being enough to cause burning sensations, numbness, temporary paralysis of the mouthparts and even respiratory depression in the predator.  Perilporps have not existed as a group long enough for truly effective visual mimicry to evolve in unrelated porplets, but other species will frequently socialize closely with them while grazing for protection, using the poisonous species as a living shield to discourage enemies from coming after it. As long as these interlopers are not more numerous than the perilporps they mingle with, carnivores will usually not risk taking one on even though it lacks the bright warning colors of its fellows: the risk if it is wrong in making its decision, even if it knows the drabber individuals are probably safe to eat, is simply too great if they are mixed among the deadly ones. 

Not all who make their living from the sea do so by moving there full time. For flying species, it is often possible to hunt from the air, and return to the skies once well-fed. This is the lifestyle of the pterdevil and the spearfisher, two very different, widely unrelated animals that have both evolved to hunt for fish on the wing.

The pterdevil is a descendant of the tribbfisher, one species in a wider group of descendants which live worldwide along the seas and rivers of the world. Like all tribbfishers, they are visual hunters equipped with eyes that filter horizontally polarized light to remove glare (this was described in more detail here, just above the tribbfisher art.) Their specialized eye structure and its resulting effects render the tribbfishers extremely good at hunting prey underwater from the air, and in the hothouse age has allowed this group to maintain an advantage over most pelagic seabirds. This species is part of a family of species known as handstanders, for all of them are forelimb-bipeds on the ground, with long wings and blunt, hoof-like arm claws, but very short hind legs and hind feet reduced to a pair of small hooks. Handstanders spend most of their lives flying over water, hunting marine animals from near the surface that they locate during daylight hours, spending the night sleeping on the wing at higher altitude, as they are not buoyant enough to sleep floating on water like birds (like in some marine animals, these tribbats sleep with one hemisphere of the brain at a time and one eye open to watch their surroundings, flying in wide circles over the sea.)

Handstanders occasionally rest on shore throughout the year in groups on isolated beaches or cliff sites, but can spend months at sea. They must come to the ground to breed, however, for their young are born at an early stage of development, which prevents the mother from being encumbered by the weight of a large fetus as she flies, but also means that the pups are utterly helpless for several months after birth. Pterdevils are a migratory species that winters on the open ocean, but flies inland to the polar basin to give birth, taking advantage of the short but productive summer season to hunt and raise their young before the polar night returns. Males arrive up to a month before females, flying in twilight, in order to establish territories along ever-shifting sandy islands within a mile of the shore of this inland ocean, where land-based predators are unable to reach but the water is still not very deep. Each of these islands may form from the movements of coastal sediments in a matter of years and, through continued erosion, move from place to place, break up, flood, and reform again, meaning they never have time to develop much in the way of thick plant life.

These barren sand or gravel plains provide an ideal site to gather in large numbers, and each year the entire breeding population of pterdevils will gather on just a few of these islands. The males are much bigger than the females, standing around three feet high with their long horn-like ears, and sporting a wingspread of about six feet. They posture, squawk, and strut along stretches of beach, sparring with each other over land claims, and over the weeks the bare skin of their throat and their ears take on pink to crimson red hues that contrast strongly against their white fur. When the little females arrive - colored in earthy browns and with wingspans of just three feet - they each choose a large and colorful male with a higher quality territory, one unlikely to flood over the course of the summer, and only about 10% of males will ultimately end up with a harem, with the rest spending the summer alone on the edges of the colony.

Females mate and are pregnant for just twenty-one days. Usually two pups are born, and they are left on the ground without even a semblance of a nest. Newborn pterdevils are only a couple of ounces each and born completely blind and hairless, but grow very rapidly, to the point they are able to fly in just four weeks time, and by then closely resemble tiny versions of their parents. The female alone feeds her offspring, for the first week or so relying on a regurgitated slurry of semi-digested food she has stored in her throat pouch, but then having to leave them daily to hunt. The pups at this age cannot warm themselves effectively and could easily cool, even in the warm, humid atmosphere, for it averages some 20 degrees below their body temperature. To keep warm, the dozens of pups in a single harem are carried by their mothers into creches, which are guarded from predators by the male while the mothers are out at sea finding food. When they return they identify their own young visually - not by voice, as birds most often do - identifying some small trait that signifies their own young among many others which to us would seem identical. They ignore unrelated pups, and if they beg females that are not their mothers for food, they are tossed aside callously. Orphaned young will only be accepted by females whose own pups have died, but in a large colony such mourning parents will always be present in some number, so that with enough persistence orphans may manage to find a surrogate. There is a time limit to childhood here, however, and every missed meal lowers their chance of survival - even if they find a new mom.

Around one month of age the pups have become active and curious, jumping around the beach, and begin to take short fluttering flights. They harass their mothers quite boldly now for food when she returns, jumping all over her and biting at her face. It may not come as too big a surprise that she now grows tired of them; at five weeks of age, with very little variation, the females synchronously abandon them, even those which have fallen behind the growth curb and are not ready to fly, for the colony is only safe when there are large numbers. The harem males leave just a few days after the females cease to return, letting the unsuccessful males along the edges access into the colony, where they may take the opportunity to cannibalize the juveniles. The pups which are capable soon leave the beach for their own safety, while those which are not - born too late, or fed too little - succumb to their fates, and they instinctively fly out over the water to start catching their own food. Though they know to follow adults of their species to locate shoals of fish, they are provided no further guidance, and mortality at this stage is significant. In another month, with good fortune, they will be about half the size of the adults and strong enough to follow them back southwards to the ocean on the autumn migration. Well-fed females may be able to breed as soon as the next summer, but will usually wait two seasons to fly north again to do so, while males take three or more years to reach full size and stand any chance at claiming a territory.

The spearfisher, meanwhile, is a beautiful skewer, one of the most graceful and elegant of them all, that is widespread over the coastal waters of northern Serinarcta and inland throughout the polar basin. These birds are not overly big and weigh about as much as a large pigeon, however their long arcing wings make them appear more substantial in flight, extending almost 4 feet across. These wings are suited for gliding on rising air currents, which the spearfisher does frequently to rest, as it has no feet at all to speak of, and almost never lands off the water. 

This bird is a descendant of the white-tipped skydart that has diversified its behavior enough that it has diverged into its own genus that doesn't interbreed with its ancestral forms any longer. They are coastal seabirds which now feed mostly on fish, which they do by following the keener-eyed tribbfishers to find bait balls below the surface where prey has already been rounded up by marine predators into a tightly concentrated swarm. The spearfisher then rises rapidly upward with powerful wingstrokes, and then spirals downward at great speed, lifting its wings up at the last moment and crashing into the water with enough force that it spears any fish it strikes as it shoots down into the baitball. The vertebrae of its neck and the joint of its bill are fused for durability, so that they can endure the great stresses put upon them as it strikes its prey, and its nostril openings have even moved backward so that they don't take on water when they strike the surface; they now face toward the eyes. The bird then rises and takes flight from the water's surface with its beak lined with neatly skewered food items. While they appear to be beautiful, almost angelic animals in flight however, don't be fooled: the spearfisher is an aggressive animal and a pirate, which will make away with food captured by all other sorts of flying animals, using its superior agility to outmaneuver both tribbfishers and even other, stronger pirates like villaingulls and take their meals. In contrast to a majority of skewers, but typically for many skydarts, the spearfisher is diurnal.

Spearfishers need all the fish they can get because, unlike earlier skydarts and ice age skewers, they have begun to practice some level of parental care. Descended from birds with larvae that fed on the protein-rich refuse and carcasses below mowerbird breeding colonies, spearfishers have large and voracious larvae with a need for meat in their diet. The adult female now prepares a nest and a stash of food for her eggs to hatch within, collecting a pile of fish and hiding it in a cliff ledge under a huge pile of seaweed, sometimes as big as five feet around, which may take her two weeks to compile all together. The seaweed heap will retain moisture and help hide its scent from scavengers, and by the time she is done, the fish will begin decaying - making it both be more easily digested by her grub-like young, and less appealing to other seabirds with stomachs that aren't as adapted to eat rotting carcasses. Laying her clutch of eggs within this nest, she then leaves them to fate; the fortunate ones will feed on the fish and then pupate within the depths of the nest, taking flight in a few months ready to take care of themselves.  

The last land-turned-water creature seen today is a bit of an outlier. Like the perilporp, this one is another herbivore. Unlike all the rest of the species here, though, it is not yet a true sea creature. It has evolved in northern Serinaustra's soglands, and is still a denizen of freshwater habitats. Though the central soglands to the south are becoming drier over time, this is not true in the northern reaches of Serinarcta. Lower overall land elevation as a result of ground carved by the movements of huge glaciers in the ice age means this region remains a land of lakes even fifteen million later, the biggest of them all being the incredible polar basin, an inland sea currently situated over Serina's north pole, which is 1,200 feet deep at its greatest depth. All of this water means that the best way to get around is to be a good swimmer; most thorngrazers are predictably scarce here, for none of them can float well, and only a few specialists like the hadropotomus can cross water by bounding along the bottom. This is a region dominated instead by other herbivores: strange trunkos, gantuans and their relatives the skulossi, and a variety of grazing tribbetheres that are the descendants of tribbybaras. 

Tribbybaras have many things in common with thorngrazers. In particular, they have similar skulls and large grinding jaws, being distant relatives among the molodont lineage. But unlike thorngrazers, tribbybaras are buoyant. Without osteoderm armor in their skin, they can swim well - and this gives them a great advantage over their relatives in the wettest parts of the northern soglands. Within just five million years, the tribbybara itself has evolved into a variety of new species, among them the aquatic tribbocampus - a plump herbivore that resembles something between a manatee and a hippopotamus.

Though the tribbocampus, with its feet all turned to wide, webbed flippers, can still walk about as well as a sea lion if it must, it rarely leaves the water. It prefers to float along effortlessly through flooded plains and shallow lakes, where it consumes a diet of floating vegetation and the tops of willowy aquatic grasses that grow their long blades continuously from a root system as far as 30 feet beneath the water. It occurs in great herds sometimes numbering over a thousand where the water is wide enough to sustain their numbers, as it finds safety from enemies in the company of many of its kind, but within such large gatherings are many smaller herds. Like the tribbymara to which it is not too distantly related, stable social structures with familiar individuals are central to the life of the tribbocampus, and all adults in the group help to watch the young as they paddle along the surface like weird little ducklings in a large creche and gobble up floating leaves. Young are born very small relative to their 500 lb parent; each weighs about eight pounds, and as many as ten are born at once. While adults can dive and hold their breath to graze submerged plants, and their precocious pups feed themselves within just a few hours of birth, they can only hold their breath for about a minute when they are born. This means they must spend most of their time on top of the water, where they can be vulnerable to airborne predators and even some aquatic ones, so that mortality is high and only a few can be expected to reach adulthood; in this way the tribbocampus is much more r-selected than most animals of their size like thorngrazers, which bear only a single large calf at a time, even though they arguably take better efforts to keep their larger broods safe than their relatives with fewer young.

The tribbocampus spends so much of its life floating near the surface, with only its eyes and ears exposed, that it has begun to evolve a pupil shaped specifically to improve its eyesight on the edge of water and air. It is pinched in the middle, while long and horizontally stretched both above and below, and the lens of the eye is shaped differently on top and bottom to focus best in either air or water, like a set of bifocal glasses. When at rest in freshwater, the animal's center of gravity balances its head so that the water line sits exactly at the division in the eye, giving it an ideal view both above and below to spot enemies from all directions. The ears of the tribbocampus have also evolved to function better between these two dimensions by becoming longer and able to close muscularly along their length so that they open up only at their tips, poked out of the water and keeping them dry. While diving, it can seal them entirely, while if on land the whole ear unfolds so maximize its hearing. The tribbocampus needs its senses as sharp as they can be, for it is a common prey species for such hunters as snagglejaws - swimming foxtrotters descended from the finfoot tryena, which will ambush them from shore or shallows and haul them out of the water to eat; the tribbocampus has few specialized defenses except to cluster together and seek to bite their attacker, protecting their babies and their own vulnerable backsides. Though this might not seem like much, their jaw strength is still substantial and such a bite can easily break a predator's leg, meaning that hunters will do their best to catch them by surprise from behind, and are likely to be discouraged if their targets spot them first.