The Floating Forest

This biome is a collaboration between the author Dylan Bajda and Troll Man. 

The floating forest is a biome found upon Serina's oceans in the late hothouse, formed by accumulated rafts of mixed vegetation that form buoyant colonies at the water's surface. The base of the forest is brown macroalgae similar to sargassum. The species that comprise the foundation of this habitat occur widely in Serinan seas, but the floating forest's existence as a large entity is made possible by the meeting of multiple sea currents that  create an oceanic gyre, where water circulates around a patch of still water hundreds of miles across over a long term basis, keeping it from drifting apart and over time collecting it into vast interwoven floating mats which are then colonized by other plant species including saltwater-adapted species of moss and even small extremophile woody shrubs. Located in the middle of the unbroken ocean, roughly midway between Serinarcta and the Meridian Seamount, the floating forest covers a roughly circular area some 450 miles in diameter, though its exact size varies year to year.

The forest is an exceptional fertile region of Serina's otherwise desert-like open oceans, and a wide variety of marine life shelters below the forest which functions like a reef. The sea currents that meet around it deposit large quantities of nutrients and sediment carried from around the world, which is then kept from dispersing away from here by the lack of strong water movement within the forest. Over long time spans dirt accumulates within the rafts themselves, largely from the droppings of nesting seabirds, adding both to their solidity and their fertility; occasionally portions of the forest are weighed down to the extent that they sink, but the size of many colonies is so large that they remain buoyant, supported by others around them. In the oldest central colonies where soil has formed, small trees may even be able to take root. Functioning as a refuge in the open ocean for countless animals, the floating forest is extremely biodiverse.

Kelplings are little marine burdles which evolved from an isolated form of the penguipus that moved into saltwater in order to find food. Their method of finding food, and indeed how they move in the water, is very much like penguins and relies on rapid underwater "flying" with the flipper-like forearms flapping to provide momentum. The long beak is lined with fine lamellae, which provide grip on small fish prey but also can be used to sieve the water for finer particles of food, both phytoplankton and zooplankton, in areas where the nutrient density in the water is especially high.

The kelpling is now native to ocean environments away from shore, in places where the soil burrows their ancestor used to incubate their eggs simply do not exist.The forest, which is suspended below water by the airfilled bladders of the algae rather than actually growing up from it, is an exceptional fertile region of Serina's otherwise desert-like open oceans, and a wide variety of marine life shelters below the forest which functions like a reef. The sea currents that meet around it deposit large quantities of nutrients and sediment carried from around the world, which is then kept from dispersing away from here by the lack of strong water movement within the forest. Because the water is calm here, and there is hardly even any wind to cause wave movements, in places the algae can link together and form spongy islands which are sturdy enough that a human could stride across them without falling through. And it is on this floating seaweed that the kelpling constructs its nest.

Kelplings can no longer walk on land, not that they typically even see land now. Their torpedo shaped bodies are, though, ideally shaped to swim. Their feet, not used much in the water, remain able to grasp, and are often used to collect seaweed and weave it together into their own miniature islands as a safe place to lay and brood their eggs. They could just lay their eggs on naturally-occurring seaweed islands in the forest, and some do, but it is easier for the parents to protect their young from predators by choosing a smaller and more insular nest that is harder to sneak up on. Both sexes partake in nest building; females do all incubation, but are fed by the male throughout and so do not have to leave their nests. Six to ten eggs hatch in about five weeks into precocious little chicks which can swim within minutes of hatching. The chicks find all of their own food, and seek shelter from enemies by hiding in the tangled seaweed, needing no additional care from mom or dad once they are hatched.

Sailbirds are a small family of pretenguins descended from guingrebes. They are the only marine representatives of that lineage, though not all species are oceanic. Comprising three genera, they are allied by their massive size and high buoyancy that usually prevents adults from diving, at least for more than short duration or to great depth. Species like the violet sailbird of the floating forest are the heaviest sparrowgulls ever to live, and can weigh 2,000 lbs. They are featherless, but their skin is often brightly colored, especially in the case of this species, the male of which is mostly a vibrant violet shade that helps him attract a mate. 

These giant pretenguins are omnivorous, and feed by lowering their long necks below water to graze on water plants and any small animals that hide within them. They usually favor calm coastal waters or large freshwater lakes near the equator, but violet sailbirds live far out to sea, within the floating forest, where there are no strong currents to push them around, and where food is very abundant at surface level all year round. Traveling in groups, they move slowly over the water's surface like a fleet of ships, dipping their heads below to snatch up mouthfuls of seaweed or to filter plankton from the water with comb-like notches down the length of their beaks. These birds have been able to reach such large sizes because guingrebes do not need to nest; females alone incubate a single egg while rolled over, leisurely drifting about on their backs. In these large guingrebes, it is cupped beneath a fold of fat and kept both warm and dry for the several weeks it takes to hatch. Though these birds often rest on mats of seaweed and use them like pool floaties, they can no longer move on dry land or properly leave the water. While the adult lacks many predators in its sheltered habitat, which is too thickly vegetated for most larger open water predators to easily access, the chick is only twenty pounds at hatching and is very vulnerable. A real momma's boy, the baby is often cradled by its mother for safety until it reaches several hundred pounds - which only takes a couple of months - by which time the soft white down feathers it hatches with are lost and it can keep warm in the water with only a thin layer of blubber to insulate it.

The floating forest's central location between multiple major oceanic currents means that this is the ultimate resting place for a substantial percentage of oceanic debris. This includes many natural rafts - large collections of driftwood and vegetation, sometimes also containing soil substrate, which routinely break away from continental coasts and wash out to sea, often carrying with them small animals. Such rafts occasionally transport species between continents. But sometimes, they bring unexpected life to the forest far out at sea. 

Sailorsquorks are goose-sized natatory scroungers which are found only upon the surface of the floating forest. They are most closely related to the castacranes and their descendants on Serinarcta, the two groups sharing a common ancestor which was somewhere between the two in its appearance - a fish-eating wading bird that could both swim and run over land. Isolation has caused the two lineages to become quite different, with castacranes returning to land and losing any semblance of their aquatic adaptations, while sailorsquorks have exaggerated their own, developing wide lobed feet similar to the squelicans to swim, but not quite losing their long-legged body plan. The sailorsquork, whose ancestors were carried here from more coastal regions more than five million years ago, now lives a strange life, largely on top of the expansive floating seaweed rafts that cover most of the floating forest region. With long, splayed toes, this animal can run over the surface of the forest much as if it were solid land, though thin patches may sometimes result in it slipping through into the water. This too is fine, however, for the sailorsquork is a strong swimmer and very bouyant, and if it becomes lost in open water, it can float for several days and even sleep in a neutral resting position. 

These scroungers aren't fast hunters, so they prefer to catch prey that doesn't run quickly. They eat mainly crustaceans and bivalve molluscs which cling to the underside of the forest, and have developed very muscular, somewhat short tentacles useful to pry apart such foods from their protective shells. Walking along the rafts' edges, the sailorsquork reaches in and snatches prey it spots at the margins; if this is not productive, it will slip below the forest and hunt its prey in the shadows beneath, able to hold its breath for short, productive dives each as long as six minutes. This species is not highly social, even when breeding, and is rarely seen in groups larger than two or three - the latter usually being a pair and their dependent young. Nesting occurs on the surface of the forest, with the male constructing a shade structure around his partner as she sits on her egg, building it from any refuse that he can find, including plant fronds and pieces of driftwood.

Under the floating forest lurks a menacing animal called the bonespitter. A small waterhog whelican, it weighs no more than 250 pounds, and is about as long as a human is tall. What it is lacking in size, it makes up for in viciousness. This little marine scrounger is a feared predator - for it can strike at any time, in nearly an instant, and it kills its victims in among the most brutal of ways. 

With a very long snout tipped in four sharp hooks, the bonespitter finds prey with its strong sense of smell. It shares with other waterhogs the unusual arrangement of nostrils which open into its tentacle net, just above its mouth, and thus are entirely hidden, as each of the four tentacles making up the snout are connected with a stretchy patagia of skin. To breathe, it pokes just the tip of its snout above the water and sucks in air, limiting how much of itself it must expose to get a breath compared to other whelicans with nostrils that open on the top of their heads.  This also allows the bonespitter to hold an air bubble within its tentacle net, pressed against its nostrils, and use it to absorb scent molecules from the water even though it still breathes air.

Bonespitters mostly hunt below the surface of the floating forest by night, detecting seabirds and other small animals that land on the surface of the seaweed to roost. When they smell prey just above them, they close their tentacles together and press into the interwoven mat of vegetation that makes up the structure of the forest. Normally, the four hooks on this scrounger's face are positioned inward, to catch prey. But now, each tentacle rotates so the hook faces outward. The bonespitter then slowly opens its tentacles, tearing a small hole through to the surface and directly beneath its prey. Then, in an instant, this sly hunter shoots its tentacles up through the gap, stretching them up to twice their resting length and snagging its victim. It is dragged below the water before it can cry out and alert its fellows, and sucked down into the bonespitter's expansive gullet in a rapid torrent of water. A muscular gizzard grinds the prey apart as it is sucked back and forth against its rough surface in the whelican's throat for several minutes as all the hard pieces  - bones, scales, claws and feathers - are mechanically separated from the soft meat. Then, the hunter simply spits out the parts that it can't easily digest, and the meat slurry is swallowed into the stomach. All that remains of a seabird is a soggy tangle of feathers and neatly cleaned bones, left to drift away in the water as the bonespitter moves on to the next meal of the night.

Bonespitters are close relatives of fanged waterhogs, and likely evolved from a species similar to them. They differ in their prey choice, though, which is always small enough to swallow whole. Like other waterhogs, bonespitters brood their eggs on "land", though still keeping them warm within their mouths. Their land, of course, is the surface of the floating forest itself, and they are among the biggest animals that gather to rest on it.

There are many animals on Serina which will eat birds, because a very significant portion of all animals on Serina are birds. But there is one animal who's diet of birds is unexpected enough that it can acquire the name of ornivore. And it is a very aberrant animal indeed.

The ornivore is a late-surviving, semi-aquatic, and highly venomous eelsnake that is distantly descended from fangworms, a lineage which has been historically scarce in the hothouse, despite one species surviving the great thaw. It is a strongly snake-like animal, descended from a clade of fully-marine piscivores which used their very venomous bites to rapidly dispatch fish, and so not give them any time to escape into deeper water, out of reach. But it is very odd even among an already derived fangworm clade for its other traits: its skull is very elongated, its own snout almost bird-like. Further, its body has elongated in an unusual way. Though it has no fins, or any limbs left at all externally, almost half of its body is located in front of its shoulder girdle, where it front limbs once were. Half of the ornivore is made up of neck - and it is thus the longest-necked of all ray-finned fishes, few of which outside tribbetheres have any true neck at all. This very strange arrangement evolved to allow the ornivore to extremely rapidly strike at its choice of prey - seabirds - without the part of its body that it shoots forward to do so being weighed down by internal organs. 

Ornivores are inhabitants of the floating forest, itself a very unusual biome, and it is here that this formerly pelagic animal adapted itself again to live on the fringes of something at least similar to land. It has lost the flattened tail of other relatives, as it doesn't need to swim long distances here, and it has instead become thin and wiry, to slither through the seaweed. It is a very thin animal, but can reach lengths of 16 feet, eight feet of that length able to launch vertically upward to ambush passing seabirds. The jaw is lined with many long, hook-like teeth, but the front-most top incisors are hollow fangs which deliver a cocktail of deadly venom, sufficient to stop a bird's heart in seconds and so prevent it from struggling and potentially damaging its jaw, which is very lightweight in order to strike quickly, and thus fairly fragile. 

These fangworms are not highly adaptable animals - they are specialists, with little to no behavioral plasticity. This species feeds exclusively on flying birds and rejects all other food completely, and such birds always caught from below in the same way. It is an instinctive feeding method ingrained to such a degree that it does not recognize prey in any other context; a bird perching on the vegetation next to it will not be in any danger, nor will one swimming in water down beneath it. And yet, in its isolated environment, the ornivore is widespread and successful, as are many other contemporary specialists which - for now - have been able to forgo more complex behavior in the relatively forgiving hothouse climate, where food is often easy to find.

The secretive seastrider is a marine burdle endemic to the floating forest, quite common, but rarely seen on account of its slow moving habits and excellent camouflage. Related most closely to the blighters, seastriders of this genus split from them ten million years ago. They, too, are covered in protruding scutes, but theirs are not for defense. Rather than being hard, thorny projections, those of these animals are soft and flexible thanks to collagen fibers in their structure. Some of these extend out from the animal's epidermis for over 6 inches, forming tendrils that move around in the current like seaweed. This is their purpose, for as these creatures slowly amble through the tangles of surface vegetation, their shape is obscured, hiding them from predators among the algae.

Secretive seastriders are bigger than blighters, reaching a length of up to 30 inches, and a weight of twenty pounds. Yet they are not a destructive force and have no swarming tendency. Solitary, though sometimes found incidentally near one another, they are selective feeders that benefit the floating forest rather than deplete it. Their diet does include some seaweed, but their preferences are for invertebrates with hard shells, like bivalves and filter-feeding snails, which collect on the forest and can, over time, weigh it down to such a degree that portions may break loose and sink into the dark waters below. Secretive seastriders search the forest for these organisms, reaching their long beaks into the weeds to pluck them out, crack their shells, and then swallow them whole. In doing so, they control the numbers of these clingers-on, and ensure their habitat remains buoyant in the productive sunlit surface waters it needs to survive. Secretive seastriders swim with their back legs while keeping their front ones folded up, but they only swim rarely, much preferring to crawl beneath the forest, where they are less visible to their enemies. When at rest, they may wrap themselves up in the weeds and effectively vanish from sight. They can go for up to four hours between breaths of atmospheric air, thanks to a naturally slow metabolic rate and the ability to absorb oxygen from the water through their many thin, vascularized scutes, which incidentally increase their surface area, and can function as simple gills to supplement their oxygen requirements.

Reproduction in these seastriders has some aspects in common with the blighter, but occurs less frequently. A female, when she is expecting a typical clutch of three eggs, burrows upward into the forest to create a sheltered burrow just above the water, but hidden from the surface and the drying effects of the sun. There she deposits her eggs, and then pushes the seaweed back up against them from below, creating a hidden, warm, wet, and oxygenated nursery for them to develop, warmed just enough by the sun above to speed up development, but not so much they dry up or cook. A single clutch may be laid every three weeks, but sometimes less. Her diet, high in calcium from the shells of molluscs, quickly replenishes the minerals she uses in producing her eggshells, but conditions suited to laying eggs are not always available, as the thickness of the forest varies over time; too dense, and her young may not be able to free themselves from the vegetation when they hatch, but too thin, and they may be inundated with water and drowned, or exposed to the open air and drowned or predated. They can survive for a period underwater thanks to a large air sac, but not longer than half a day. 

The sea skueasel is the biggest lutrine skueasel descendant, reaching seven feet long and weighing over 150 lbs. It is a marine griffon which feeds primarily on coastal molluscs, and has a more robust beak without a second "fang" serration as is seen in other skueasels. Able to hold their breath for ten minutes, these skuorcs dive to depths of over 150 feet and agilely slide though the water, propelled by a robust, paddle-like tail. Food is generally collected in the paws and taken back to the surface to be opened. These animals float on their backs and hold additional portions of food in their back paws, taking them one by one into the hands to hold in place and gnaw on the muscular hinge with their beak to access the meat inside.

Sea skueasels are gregarious, something atypical among skueasels, and live in pods averaging four to sixteen adults which rear young in a collective creche in a sheltered coastal bay where large marine predators cannot reach them. Litters from each female are small, usually three or four pups, but they are bigger at birth than in many skuorcs relative to the parent and can weigh nine pounds each.  Young can swim immediately but can not dive well for several weeks; they are naturally bouyant, with a high percentage of body fat and thick, fluffy feathers which the adults groom regularly to trap air within their undercoats for insulation. Young are fed by their mothers, and guarded as a group by at least one adult member of the pod at all times. Males engage in parental care too, though less reliably, and are most attentive to the young of a single preferred mate; as in draguars, their closest living relatives, the male takes a more proactive role as his young become more independent, and then may take them on excursions to hunt. A sexually dimorphic species, male sea skueasels are brightly colored with four yellow feather crests on their heads and bright orange bills; females have only a single smaller crest over each eye, and their bills are a dull grey, sometimes with a yellow tip.

Sea skueasels are occasional vagrants to the floating forest, but unlike other species discussed here, don't breed there. They also occur along the western shore of the polar basin, where an endemic subspecies exists which is smaller and less ornamented, the species having reached this freshwater biome through riverways around half a million years ago. Their preferred habitat is rocky coastal regions where their food can find suitably hard attachment sites to grow, which can suit them in both fresh and saltwater habitats. Though capable of being fully marine, even being able to sleep at sea by floating on their backs in calm waters, these animals prefer to roost on land and so rarely venture more than a day's travel from shore, wherever they live. 

The vast oceanic habitat of the floating forest is a veritable undersea jungle, harbouring hundreds of unique endemic species living in close proximity. Many relationships between different animals have developed over millions of years as the environment grew and evolved. Those of predator and prey, parasite and host, niche partitioning of competitors, and the symbiotic relationships which benefit both parties. The sea pony is a relatively small species of sea horse tribbetheres, growing between four and five feet in length, and lives in great herds in the floating forest, sometimes hundreds strong. Their rotund bodies are rather buoyant, and they rarely stray deeper than a hundred feet underwater, for they thrive on the countless hundreds of miles of macroalgae that drifts near the surface and grows with such speed and quantity to the sea ponies it is functionally infinite. Indeed, they defecate almost as quickly as they feed, fertilizing the seaweed and accelerating its growth. Their striated hides acts as perfect camouflage as they slowly cruise through the sunlit understories of the vast seaweed forest. Sea ponies are born with a much brighter yellow colouration, which helps the adults easily keep track of them in the green-blue waters. As there are few predators in this habitat capable of hunting an adult sea pony, breeding is slow, with one large calf generally born every two or three years, and mortality rates are generally low. Care is communal, with all adults in the group tolerating juveniles, although close family members tend to be more actively protective and willing to respond to play initiation.

Large calacarnas and sea serpents are the primary hunters of sea ponies, but these are generally vagrants to the floating forest, as this is an oasis which does not support life at such a scale. The nimble sea pony can easily nestle itself deep into the masses of floating algae and become impossible to reach for larger predators. Their smooth shape allows them to root deep into the colonies of seaweed to graze on the newest and softest growth, as well as find the fruit-like sporangia when the algae flowers, and they even sleep by resting on top of denser clumps of the kelp-like vegetation near the surface. Although they are in fact small enough to actually haul themselves onto the surface of the floating forest like a seal, as they are still recently enough descended from a land animal that they still retain some adaptations for supporting their body weight out of the water, although their mobility is obviously very poor.

As the aquatic molodonts push their way through the tangled root-like growths, they disturb and flush out many smaller organisms which dwell within the seaweed fronds, and this has not gone unnoticed by the weedy calacarna, a small species reaching about a metre in length (including mandibles). The weedy calacarna is too small to be a threat to a sea pony, even a calf, and often follows their herds, snatching up any small fish, snarks, annelids, and other small aquatic creatures accidentally unearthed from their foraging. Its thin jaws, lined with numerous fine serrations, are well-adapted tools for grasping small, slippery prey, but basically useless restraining animals close to their own size. The calacarnas swim very close to the sea ponies, shadowing their movements, changing the patterns and colours of their own skin to closely match theirs, making their presence and approach unnoticeable as they close in on their prey, which are not automatically alerted to danger by the passive movements of the harmless herbivores as they would be to the predator alone. Sea ponies are a preferred host due to their peacefulness, large size, and numbers, allowing the calacarnas to quickly move between individual sea ponies as they close in on prey, which usually ignore them. However, weedy calacarnas are not obligate symbionts of sea ponies and just as often found by themselves, so the prey does not grow to associate the presence of sea ponies with the calacarnas.

The calacarnas have short, rounded fins and an elongated body; this makes them slow-moving while swimming in open water, but it is able to lithely crawl its way through the floating forest vegetation with easy, using its fins like arms and legs to push its way through. Indeed, its slow swimming speed makes it seem like less of a threat to its prey, which sometimes do not even register it until it surges forward with a short and sudden burst of speed. Away from the herds of sea ponies, it can hunt by hooking its tail fins into the seaweed and hiding with only its mandibles exposed to the open water, and lunging forward to snap any small swimmer that gets close enough. The snarks form pairs or small family groups and defend this communal hunting ground. When in the presence of sea ponies, they make themselves useful by scrapping away dead skin from the hides of the tribbetheres and removing dermal parasites, which helps to clean the sea horses, although the calacarnas are more interested in an easy food source to supplement their normal diet. Sea ponies have also learned to recognize some of the visual signals the calacarnas, such as the rapid flashing indicative of approaching danger. The weedy calacarnas will also actively make themselves useful to the sea ponies by helping herd their offspring and steer them towards the herd if they stray too far, which helps the ponies tolerate their presence. In these ways, the sea ponies are benefited by the snarks' presence.

One of the most common varieties of snark during the hothouse era is a subgroup of deepwater escardines known as the mothfish, named for their broad and expansive front fins. Although small, never measuring over a foot in body length, and having only a few dozen species, they exist in utterly vast shoals that can number in the hundreds of billions or even into the trillions. However, their sheer numbers are often unapparent due to the fact they spend most of their time in the twilight zone, far away from starlight, only rising at night en masse in one of the largest migrations of animal life in the world to feed on the swell of planktonic life that drifts to the surface. Unlike on Earth, there are no truly massive (blue-whale-like) filter-feeders in this era of Serina's history, and in their place are animals such as these; plankton-eaters which are individually tiny, but exist in such massive populations that they, by biomass, make up a significant fraction of animal life on Serina and are a crucial link in the marine food web, being a staple prey item for a huge number of seagoing predators and filtering countless megatons of marine snow as it falls from the shallows, cycling the nutrients. Despite this, you might not even know such animals exist if you lived your entire life on land or in the shallows, since they are only found in waters far from the coasts, and their nocturnal emergences make them highly elusive.

Mothfish are unusual for being one group of escardines which have re-evolved fore-fin propulsion, while the tail fin has been relegated to being a primarily immobile rudder. Because they feed mostly on plankton, marine snow, and occasionally, small free-swimming animals, their rounded fins are used only for keeping them stably afloat and adrift, and are not built for speed; they primarily rely on their uncountable numbers for defence. The pelvic fin equivalents in the mothfishes have been modified into stalk-like communicative organs with bioluminescent tips to help coordinate their shoals. Because they live their existence in perpetual dimness, their eyesight has greatly atrophied, and is now incapable of distinguishing objects more complex than vague shapes, although it remains sensitive to light differences, allowing their glow to remain effective visual identifiers. This feature is in part from what they derive their names, for they are drawn to these lights like a moth to lamplight.

The starlight mothfish is an unusual species of mothfish because it spends its entire life near the surface rather than engaging in nightly vertical migrations from the depths. This is because it dwells in the eternal twilight of the floating forest, a vast interconnected flotilla of sargassum-like macroalgaes stretching for over a hundred-thousand square kilometres in the midst of the Unbroken Ocean, where the constant shadow of such densely-packed floating flora simulates the dimmer conditions of the mothfishes' usual daytime dwellings close enough that one species became adapted to the oceanic oasis, where food was plentiful in the midst of a region that otherwise required their shoals to travel far and wide to sustain their numbers. In particular, they have adapted to feed on the organic film of bacterial and protistic microorganisms which settles upon the fronds of the seaweed, as well as the tiny planktonic animals which feed upon it, grazing upon them with their eversible proboscis like a gigantic herd of tiny underwater cattle, while leaving the macroalgae itself unharmed. This helps promote the health of the floating forest, clearing out competing commensals and parasites, and is in turn a reliable food supply due to the fast growth rate at which it reappears. They can also feed normally on plankton, free-floating algae, and organic particles in the water column, and are surprisingly effective scavengers. A normally passive school can suddenly turn into a ravenous horde upon the scent of decaying flesh in the water, scrapping away tissue with rows of chitinous hooks normally used for filter-feeding or biofilm grazing.

When kept in balance, the mothfish are ultimately very beneficial to the seaweed, but in greater than normal population booms, they can briefly swell to plague-like numbers where they can subsume most of the available edible matter in the water which fuels the growth of the seaweed, becoming detrimental to the ecosystem's health. Like many pelagic escardines, mothfish breed continuously, giving live birth to smaller, but otherwise near-exact replicas of their parents, capable of swimming and feeding themselves from birth. In a single year, a female starlight mothfish can birth over a hundred young, which in turn are able to themselves reproduce within five to six months, contributing to their great numbers. Although reaching only four to five inches in body length, their total population normally ranges from several hundred million into the low billions, depending on seasonal conditions, making them by far the most common endemic of the floating forest, and this single species make up roughly one-third of the ecosystem's total animal biomass (although, by mothfish species standards, it's actually rather rare). They are one of the fundamental building blocks of the environment's food chain, and are a regular menu choice for most of the floating forest's aquatic hunters, which usually keeps them from ever becoming overly numerous.

When threatened, the starlight mothfish clumps together into dense, synchronized shoals, their pigmented skin shimmering and moving in a swirling mass in an attempt to make it more difficult for predators to pick out an individual out of groups often countless thousands strong. In the darkness, the mass twinkling of such mesmerizingly coordinated escardines drifting just beneath the shadow of the buoyant seaweed masses resembles a constantly shifting landscape of stars in the night sky. While feeding close to the seaweed, their speckled, dark-green skin renders them hard to differentiate from the mottled green fronds of algae that surrounds them; it is not uncommon for a larger swimming animal to brush against a seeming innocuous clump of seaweed, only for hundreds of the small marine molluscs to suddenly emerge from it, frantically flapping away instinctively from a possible threat. An extremely high rate of predation by many shallow-water carnivores that normally do not encounter mothfish often is the price the starlight mothfish pays for their existence in this oasis.

With the evolution of giant, macropredatory calacarnas, and other such predators capable of hunting equally giant shimmershiners, like sea serpents and snippers, there has been a proliferation of more extreme defences amongst these huge marine snarks to counter them. Simply getting larger was infeasible as they risked constant starvation at large sizes and their predators grew larger still and able to hunt them in packs, so they became faster, smarter, more numerous, armed to the teeth, or coated themselves in thick armour. The macebacks are a subgroup of shimmershiners which have fortified themselves with batteries of bony spines, calluses, and plates on and underneath their skin, growing massive and bulky to present themselves as nigh-impregnable living fortresses. To reduce weight, they have developed air bladders to help counterbalance the mass of this armour when swimming, although most species are bottom-dwelling animals. Unlike the primarily filter-feeding sabrefins, macebacks are largely incapable of great migrations between fertile feeding grounds due to their bulk making long distance swimming strenuous, so they have become comparatively sedentary grazing animals, feeding primarily on aquatic vegetations. Compounding the mass from the armour is the large gut they have developed to digest this, resulting in a much longer and more rotund frame than the sabrefins, as well as a very enlarged proboscis filled with rows of plate-like grinding teeth for macerating plant matter.

Most macebacks are founds in shallow waters, as only these rich sunlit waters provide the lush meadows of marine grasses, seaweed forests, mangrove canals, and alga-encrusted reefs that can support them, and they are able to easily rest on the seabed, but there is one species which survives far out in the middle of the Unbroken Ocean. Here is an oasis in the midst of a functional desert many thousands of miles from anything else habitable to sustained animal life, the unique floating forest biome. This collected mass of sargassum-like algae several hundred miles wide supports a similarly unique ecosystem of ocean life isolated on this shimmering emerald jewel. The largest native denizen of this habitat is the urchin-bellied maceback; although it is one of the smaller maceback species, growing between seven and ten feet in length, and potentially up to six-hundred kilograms, as the floating forest is not large enough to support populations of animals much bigger than that. Aside from some rare vagrant predator species like sea serpents or kraviathans that pass through the area, no carnivore of the region can threaten an adult urchin-belly, and they can reach exceptional ages, possibly over two-centuries, and breed very seldom.

This species likely became isolated in this environment when a maceback shoal followed a temporary current far from their fertile homelands and became stranded, but were able to adapt to the floating forest environment. The urchin-belly is unusual compared to shallow-dwelling maceback species in numerous respects to facilitate a permanently pelagic existence. Their armour is reduced to save weight, as there is no predator large enough to threaten them once full-grown. Their body is slimmer and more flexible to facilitate navigation through the tangled strands of kelp-like seaweed, which they often rest in, as it grows heavily enough in spots that it can support their underwater mass. They lack countershading, as they often spend much of their time swimming upside-down or horizontally browsing the underside of the massive seaweed barges. The adult urchin-bellies are much less socially inclined than normal for macebacks and do not naturally congregate, as their size alone is sufficient to keep most predators at bay and associating in high population densities can easily result in overgrazing, but they retain strong dark-and-light banding for visual recognition from a distance. Although they play a minimal defensive function as adults, the spikes help the urchin-bellies cut through thicker tangles of algae and are occasionally used for intraspecific conflicts, as the animals will ram themselves into one another over mating or foraging disputes, although this is uncommon.

The urchin-bellies can take up to thirty years to reach sexual maturity and often do not mate until they reach their forties, due to their very low mortality rates and very lengthy lifespan. The macebacks are born in litters of two to six, and become independent only within a few months of birth and are radically different in appearance to the adults, being far slimmer, vibrantly green, a thicker coat of spines, and with much larger proportionate fins. Due to their size, adults rarely venture into the thickest tangles of the larger rafts of the floating forest, since it is all too easy to become trapped, but the more slender youngsters can far more easily slip in-between the kelp-like strands. They often shuffle and push their way through the seaweed, rather than swim, congruently similar to the movements of early tetrapods or the distantly related gups. Unable to keep themselves safe from predators through size, juveniles rely much more heavily on camouflage and armour; when threatened, they can quickly ingest water and inflate themselves like a pufferfish, attempting to wedge themselves in the thickets of seaweed, hooking into the vegetation with their spines, while eyespots on their tail fins keep the predator's attention away from their head.

The greatest threat to adult urchin-bellies is actually starvation; during leaner years of sustained unfavourable weather conditions, the size of the floating forest can drastically shrink as the seaweed dies off. This is obviously disastrous for native animal life, but for the large macebacks that require the most food, this can be catastrophic, the entire species' adult population can drop by a third within six months in the worst famines. In typical conditions, the seaweed easily grows back quick enough to deal with their grazing, but in poor years, their grazing can have a detrimental cascading effect, worsening the shrinkage. To help cope with this, macebacks can actually shrink in size by more than a foot in length to reduce resource consumption during years of poor grazing (they grow back to normal once ample food supplies return), and they consume a greater degree of animal matter (usually via scavenging), which normally makes up an inconsequential amount of their diet due to being specialized for digesting vegetation. Macebacks become less socially tolerant during this period, aggressively staking out their feeding grounds to remain as well-fed as they can until their green buoyant rejuvenate themselves.

With the melting of Serina's icecaps has come the return of an environment which disappeared during this period of intense glaciation: the ocean depths, so far deep that sunlight does not penetrate the countless layers of ever-deepening blue. On Earth, this is the ecosystem which takes up the most space on the Earth's crust, but Serina's seas are much shallower than Earth's, and near the end of the ice age, so much of the globe's water was locked in glaciers, virtually all of the seabed was shallow enough that it saw sunlight. With the drastic global warming at the dawn of the hothouse age, sea levels rose dramatically, flooding more of Serina than at any point in its history, and changing the topography of the globe far more drastically than any sea level rise in Earth's history. Oceans became deeper than they had ever been, and once more the seafloor in most regions became plunged into darkness, as sea levels rose over two-thousand feet in tens of millennia; a blink of an eye in both evolutionary and geological time spans. This led to the demise of one of Serina's most productive ecosystems and the grandest civilization yet seen, but the darkness has since become populated by strange, abyssal life, sustaining themselves on the marine snow that drifts from the shallows; monstrous caricatures of the animals of the surface layers.

During the hothouse age, seagoing snarks dominate the oceans of Serina, and this is no different in the bathypelagic depths, so deep that the light and warmth of starlight does not reach its murk, leaving the water pitch-black and only a few degrees above freezing. Vast shoals of mothfish, often many hundreds of billions strong, cruise through this darkness on their ceaseless migrations, following the continuous trickle of marine snow, the most immense movement of animals in all of Serina, but occurring in a realm seen by very few. These mothfish form the primary basis of a strange food web of abyssal hunters, as larger fish, jellies, predaceous snarks, and deep-diving seabirds rely predominantly on them. And these are hunted by the nightmare of the depths, an invisible hunter that dispatches prey with massive, snaggle-toothed jaws. Over five metres in length and weighing up to two tonnes, this is the ogre calacarna, the top of the food chain in a world of permanent gloom.

Huge eyeballs, larger than grapefruits, are sensitive to the tiniest emissions of light, allowing it to pick out the faint outlines of prey illuminated by its bioluminescent antennae, which are each split into two branches (giving the calacarna the appearance of having four antennae). These are extraordinarily fine-tuned sensory organs and greatly elongated for maximum effectiveness, able to pick out the minute vibrational movements of swimming creatures from hundreds of metres away and detect scents in the water column carried for miles on the current, from above, below, and either side, giving it a fully three-dimensional awareness of its surroundings despite visibility being zero. The tips emit a strong red glow, allowing it to see many red deep-sea animals; this far from sunlight, red as a colour does not normally show up and many inhabitants of the deep sea have lost the ability to detect it, so numerous denizens of this environment have evolved to be red-coloured, thereby making themselves functionally invisible. However, a few predators, such as the ogre calacarna retain the ability to see red and emit red bioluminescence, as it is both invisible to most other animals and lights up the previously invisible red animals. The ogre calacarna itself also takes on a red colour while travelling through the deep sea.

Its huge tooth-like mandibular projections are used for the dispatching of prey. Because prey is widely dispersed in the deep sea and it could be many months between meals, it is imperative that it is able to subdue anything it comes across. Its primary diet consists of large, soft-bodied invertebrates, like giant abyssal jellyfish, pelagic annelids, free-floating reef snails, and smaller snark species, with its huge serrations designed to pierce, shred, and snag their flesh. Escape is unlikely once bitten, as the calacarna attempts to inflict immediate devastating wounds to cripple the animal should it prove too powerful to subdue easily. Smaller vertebrate swimmers are also occasional targets, usually caught in vertical migrations when they travel to near-surface waters, catching their prey while asleep, using their superior nocturnal senses to their advantage against animals used to sunlit conditions. They are also a regular sight at carcasses, either on the seafloor or, less commonly, floating at the surface, as their superbly developed olfactory pores allow them to detect the faint waft of rot in the water over vast distances. A floating carcass is one of the few factors which will drag them to the surface in the daytime; to prevent from blinding themselves, the calacarnas retract most of their eyeballs into their stalks to let only a pinprick of light in. The fall of a large carcass into the depths is also one of the few times where calacarnas will encounter one another, and this is most often when they mate (as the glut of meat will satiate their hunger aggression for a while, although they just as often feed on other scavengers as well as the body itself).

The floating forest, a vast oasis in the middle of a marine desert, creates a glut of nutrients all the way to the seafloor, as the activities of all the life above drifts downwards as a continuous blizzard of marine snow and other scraps, resulting the most ecologically dense parts of the deep sea on Serina, thousands of feet below the bustle of the oceanic seaweed jungle. As a result, the ogre calacarna population occur in their greatest number and proximity beneath the floating forest, and it is the region's largest resident predator. They rise from the darkness at night to scour the floating forest, ready to snatch any animal caught out in the open or not well-hidden enough in the rafts of macroalgae, like some sort of aquatic bogeyman. Its acute senses, well-adapted for darkness, give it a superb edge over the diurnal surface dwellers at night, but the cryptic colouration of many floating forest inhabitants, and their ability to retreat into the tangled vegetation beyond their reach, makes the hunt far from easy.

This is the only region where ogre calacarnas regularly associate in close proximity with one another, as they are otherwise one of the most solitary calacarna species, encountering each other only to mate and being independent from birth. Groups of them systematically navigate the under-storey, through the groves of seaweed widely spaced enough for them to swim through, and work together to tear apart and dismember prey quickly, whereas they will otherwise fight each other aggressively for food. As large predators are uncommon so far out at sea, they have little competition for prey here. As ogre calacarnas are adapted to survive long periods without food, an individual calacarna therefore only rises to feed once every few months, not every night, which prevents them from majorly impacting the populations of floating forest denizens, and may just as often only make transient visits to the regions, travelling thousands of miles across the ocean in the meantime. For such an abyssal specialist, the surface world of the floating forest is merely a pitstop in its ceaseless journeys in the deep-sea.