Millions of years ago, the wormy mitten, a small waterfowl-like aquatic predator evolved from an abberant line of the rhyncheirids, or soft-billed birds, foraged throughout the wetlands and coastal estuaries of the early Ultimocene. However, they were tolerant of saline environments, occasionally even making forays into the shallow seas. An adaptable and intelligent animal with a reliable diet, it had great success in the intervening millennia.
By the end of the latest interglacial period, the wormy mitten has radiated into dozens of species, becoming the latest in a very long string of canaries which have taken to the sea, conquering the greatest biome of all. In the past epoch, over millions of years, two distinct marine lineages evolved from this original freshwater ancestor, widely distinct from the other. Together, these two groups, along with the original wormy mitten which they all descended from, form a single clade of aquatic squidbirds.
However, their golden age is to be short, as increasing frequency and length of glacial periods causes cataclysmic damage to the ocean ecology much faster than they can adapt to. Although the sea mittens may yet survive the next coming ice age, they will never again be as diverse as during this brief interglacial period. Such is the fate of a group which has appeared and diversified during the twilight years of habitation upon this world.
Trolls (Family: Spaghocephalidae)
Easily one of the most derived of all soft-billed birds, these are indeed little recognizable to the original avian form. Their face is buried beneath a sheath of wrinkled elastic flesh, which covers the extremely elongated facial tentacles, which are by far the largest in comparison to body size of any squidbird. The trolls are so named for their method of feeding, utilizing their tentacles to capture small aquatic prey, by a combination of fishhook-like filaments, mucous strands, and simple coiling. While in effect this method of fishing has not developed far from the basic method utilized by its original wormy mitten ancestor, the reduced sensory tentacles of the ancestor have once more re-evolved to take on a more proactive role in feeding and tactile manipulation.
Despite the seemingly specialized nature of their feeding tentacles, a number of distinct feeding behaviours has developed in the different species. The majority are suspension feeders, combing the shallow seas for the rich plankton, but a number are also bottom-feeders sweeping the seabed for prey hiding in the sand. A few are ambush predators, using their longer tentacles as lures to draw in larger prey. Some use the mucous strands as a sort of net to trap small shoals of fish or fish-like swimmers. Others still utilize more unique hunting methods.
The fleshy sheath around the face of the trolls is utilized to wrap around the curled up tentacles of the birds so that they can tucked away when the animal swims about. The back legs have become stiff, flattened flippers that allow for great mobility and speed underwater, but render them incapable of walking on land. Trolls have completely abandoned the reproductive methods of their monogamous ancestors to compensate for their derived morphology (social interactions are usually solitary, although the extent varies wildly between species). Like a sea turtle, they drag themselves ashore simply to dig a hole in the sand, deposit a large number of eggs within, bury them in the earth, and then abandon them to their fate.
Despite their greater adaptations for underwater mobility, they are not particular fast swimmers among the numerous types of marine birds, and as a defence if pursued, may eject a cloud of foul, oily waste from their behind which, aside from tasting horrible, interferes with the hydrophobic qualities of waterproof feathers, making it more than a mere irritant for any aquatic avian predators caught in the cloud. An enlarged section of the colon stores this fluid, resulting in an extension of vertebrae behind the hip, which also helps to keep balance with their rear method of propulsion.
Abyss Troll (Aciabrachyavis voragomergus): A highly unusual member of an already very unusual group of marine birds, the abyss troll, as its name implies, forages on the ocean floor, making it the deepest roaming avian in the world. It regularly makes descents to the very bottom of the sea, sometimes over a kilometre deep. Using only a single breath, it can descend beneath the surface for nearly three hours, drastically lowering its metabolism and slowing its heart rate to a crawl. Pushing by its back flippers, it slowly descends beneath the sunlit waters, and as the light dims and the water cools, its feeding tentacles are engaged, capturing the abundant marine snow that drifts in the lower depths.
The species has the honour of possessing the longest tentacles to body ratio of any bird known. Its longest pair of tentacles may be more than twice the length of its body. Adults may reach between five to six feet from beak to tail, meaning these may be up to four metres long. Their length is optimal for capturing large quantities of drifting detritus while remaining relatively stationary, letting its lengthy appendages do all the work in foraging, and also for hooking deep-sea fish, molluscs, and crustaceans without alerting them to the animal’s movements. Their dark-red colour renders them nearly invisible in the blackened depths, allowing them to silently slither and curl around small pelagic prey unseen. While on the ocean floor, the abyss troll swirls its vast tentacles to sweep across the sand, “cleaning” the surface of its accumulating organic matter and any bottom-dwelling organism not fast enough to escape.
The eyes are extremely large, so large in fact that they cannot rotate in their sockets due to an oblong shape, but allow detection of the most minute amount of light (a tinted nictitating membrane allows them to see without being blinded when near the surface). Despite this, the majority of communication between individuals is tactile; with the two longest pairs of tentacles, pairs will feel each other up in a ritualistic manner in pitch darkness, with specific movements denoting anything from simple and brief acknowledgement of another individual of the same species to determing reproductive compatibility of the partner in preparation for mating. As the species is solitary and their population density very low, females will advertise readiness by rhythmically clicking their beak until another animal responds, which may sometimes take several months.
Reef Troll (Hamoceras rubicundus): A shallow-water species that hunts along the vast sea bamboo meadows and snail reefs, it is a specialized bottom-feeder, using its facial tentacles to wind through the crags and roots to try and catch prey hiding within. Hooked tentacles coated in a row of tooth-like hooks snag small animals up to a metre in length no matter how slippery, hunting larger prey than most other troll species. It is also unique among them for being the only species in which all tentacles are of equal length, and are generally shorter in length compared to body size than other troll species. This gives them greater muscle strength and control, which is necessary for precise searching within crags and restraining larger prey. The fine hairs and numerous rows of sensitive touch receptors coating the tentacles (made even more effective by a wrinkled texture which increases surface area) allow them to near-instantly identify an object as prey without needing to see it. The reef troll often follows alongside the reef-eating molodonts, catching any reef animals flushed out by their destructive feeding methods.
A naturally tropical species spread wide across the more equatorial latitudes, they are however, individually distributed far apart as these are a generally territorial species which come together only to breed. For a few weeks of the year, females become intensely nomadic, seeking out mating partners. Males form undersea bower chambers displaying their collections of trinkets artfully arranged within an artificial depression and perform elaborate courtship displays to try and impress eligible mates. Variety and colour of the items, and the gracefulness of the courtship dance are usually crucial deciding factors.
Mature females all reproduce within the span of a few weeks to synchronize their laying period, depositing between forty and seventy eggs; the vast majority of chicks do not survive their first year, but those which do will most likely reach maturity. Chicks within their first year generally forage within the first hundred metres of the coastline where larger marine predators do not venture, gradually wandering in greater depths as the smaller prey of the shallows is no longer sufficient. A full-grown reef troll may be up to four feet in body length, although it may take the better part of a decade to reach such a size.
Baleenbirds (Superfamily: Saccognathoidae)
One of many animal lineages which have evolved as gigantic marine filter-feeders; the filaments that line the sensory facial tentacles have been greatly strengthened and elongated into broad, comb-like structures, while the larger feeding tentacles have become far more flattened and stiffened, reinforced now with internal cartilage to help maintain shape, and surrounding the other tentacles in front of the face like a secondary mouth. Within the "feeding chamber", the the filtering tentacles overlap one another to form a tight mesh. Planktonic organisms are engulfed, along with water, within these, and then the water is expelled, while the combing tentacles filter out the larger particles, which are then cleaned by a long, brush-like tongue. In this sense, it is very similar to the feeding style of the great baleen whales hundred of millions of years and another world away, but evolved this in a completely different way.
However, they still lay eggs and unlike whales, have not completely separated their ties with land. Unlike the trolls, the baleenbirds retain a roughly k-type strategy of reproduction similar to most other seabirds, and usually retain the monogamous behaviour of their ancestors. The abdominal area behind the flippers is extended, with an internal "false womb" chamber where the massive egg is deposited. The abdominal region behind the legs is expanded from the ancestor to accommodate this (coincidentally similar to the same trait independently evolved by the trolls), and in some species, a rudimentary fluke has appeared for improved maneuverability. There, it incubates internally for a period of several weeks, cushioned by the wrinkled inner lining of the chamber (which does not secrete fluids to prevent smothering), and periodically supplied with air through cloacal "breathing". The male provides valuable defence, minimizing undue stress on his mate and the developing embryo. When the egg nears hatching, the female journeys to a suitable nesting site where she can lay her egg. Because it is difficult enough for the baleenbirds to move about, never mind defend their egg, on land, they typically nest on isolated shorelines or offshore islands where terrestrial predators are absent, especially since it may take several more days for the egg to actually hatch. The offspring is precocious, and within hours of hatching, will join its parents out to sea.
Sea Shepherd (Opiliovenator sp.): Technically an outgroup, but included here for simplicity, the sea shepherds are the sister taxon to the baleenbirds, representing an evolutionary link between them and the original wormy mitten. This is a monogeneric family and the small number of species are largely similar in ecological status and behaviour (the species pictured being the mango sea shepherd (Opiliovenator maculosus)), averaging between four and seven feet in length. These represent a rough ecological analogue to the pinnipeds or penguins of Earth, a fast-swimming pelagic predator, but they have adapted their facial tentacles into a unique hunting method. Hunting along the coast in the shallower waters that may only be a few metres deep, they act like a crude net spread in front of the face to drive shoals of aquatic prey into optimal hunting grounds where they can be more easily picked off. Hunting in groups, they coordinate their movement to prevent these schools from escaping.
The larger tentacles more broadly help stabilize the birds in motion underwater, and may even help with locomotion like a penguin's flippers, but are also covered with colourful, distinctive markings used for individual identification, differentiation from coexisting species, intimidation, and/or courtship displays. In some species, the shepherds can direct blood flow into them to increase the boldness of the pigmentation, or the colours naturally flush in time with the seasons. Courtships utilizing these tentacles tend to be extravagant and energy-intensive, since the animals mate for life, it is the ultimate indicator of natural fitness, and also renews their bond each year.
The species retains mobile jointed legs and feet and unfused toes, allowing them comparatively better mobility on land, which they return to occasionally. While they do not retain their eggs like true baleenbirds, they do have a shorter incubation period than most birds, lasting only around a month. Most species are too heavy to brood, and instead nest within volcanic regions, relying on the geothermal heating to warm the embryos. Young are born mobile, with a soft down that is shed and replaced by a waterproof coat within a few days of hatching (subsisting off their yolk during this period), allowing them to take to the sea within a quick period. Young are often unable to hunt for some period of weeks or months, relying on their parents to regurgitate prey while they actively learn by being taught to herd.
Superb Baleenbird (Magnophagus magnificus): By far the most massive mitten species to have evolved, a well-defined mega filter-feeder design that has persevered across hundreds of millions of years. Adult males of exceptional size may approach ten tonnes in weight and eleven metres in length, although females generally do not reach more than six tonnes and nine metres. This is the most extreme sexual dimorphism of any mitten species, as males have taken the most advantage of having completely abandoned life on land, while females still need to return to land to reproduce. This is also one of the few non-monogamous species, with the male taking no active part in rearing of young (their behaviour is complex however, and occasionally males may respond to distress calls of mothers with their young, or accompany them for brief periods as additional protection).
The species feeds most of the year in more temperate waters closer to the poles where the swarms of planktonic organisms are more abundant. The feeding tentacles are covered in biofluorescent markings that attract its prey into its mouth, a feature which is more important during the winter months, when the baleenbirds migrate to greater depths in more equatorial waters less abundant in prey to reproduce. The feeding chamber acts as a resonating chamber in the males, which boom loudly to attract females, the calls echoing for many miles. Generally, the largest males hold domain over the greatest territories and mate with the most females each season. When males of near-equal volume pick up one another's calls, they may incite combat between them if auditory and visual posturing is insufficient, battering each other's flanks with tremendous force, sometimes (although very rarely) causing fatal internal injuries.
Females tend to congregate in loose associations during the summer to better protect their offspring, when abundant food supplies allow such numbers of the massive filter-feeders to come together. When migrating to warmer waters in the winter, they return to a mostly solitary existence, aside from short-lived encounters during their largely nomadic life. The breeding cycle is very infrequent, as it can take over three years for a chick to become fully independent, and they may maintain occasional contact with their mother for years afterward.
Arrowhead Baleenbird (Litomundornis arundocephalus): A bottom-feeding filter-feeding species, this slender species acts as a vacuum cleaner, hoovering up the sand that covers the ocean floor, filtering out the organic matter, and ejecting the water and inert sand. The tentacles which make up the mouth are specialized into a self-sealing structure by way of mobile "lips" (so to speak), so prey cannot escape once vacuumed up, where undulations along its length suck water and other matter in through the tip and blow it out through a second hole at the bottom, while the long, bristled tongue cleans the feeding tentacles as the animal goes. The spacings between the bristles of the filtering tentacles are slightly larger than in most other baleenbird species, allowing most of the fine sand grains to be ejected. Any inedible matter accidentally swallowed is formed into a loose bolus within the gizzard, which is regurgitated shortly after (and it may also help grind up larger food items within during this time).
This method of feeding wears away at the filtering bristles of the baleenbird rather quickly, and the entire set is generally replaced every fifteen to twenty days. Prey of varying sizes are sucked up, and arrowheads are not restricted to tiny prey items; the vacuum created by their pumping action is strong enough to suck sea snails right out of their shells, polychaetes out of their burrows, and on some occasions, they may even slurp down small seabirds paddling at the surface with enough power to strip the feathers off. Young arrowhead baleenbirds have a relatively shorter feeding chamber and a more generalist diet, taking more free-swimming plankton, allowing them to gradually learn to hunt from the seafloor by its parents; as they transition to suction feeding, they may use their feeding tentacles to simply shovel up large quantities of sand and spit it out through their filtering tentacles.
A moderately sized baleenbird species, adults average six to seven metres in length, out of range to all but the largest macropredatory dolfinches. The bold patternings of the feeding chamber act as a decoy, distracting attackers from the duller coloured and more well-camouflaged, but more vulnerable body. The arrowhead will attempt to escape by swimming close to the seabed and churning up a cloud of silt to mask its retreat, but is capable of physically defending itself if necessary by slamming against attackers. As a full-grown arrowhead baleenbird can weigh over three tonnes, a direct blow can cause serious, if not fatal, injury to any potential opponent.
Dreadnought Baleenbird (Cephalodontornis spinifer): A species which indicates a clear parallel to baleen whales can be misleading in many cases, the dreadnought is a smaller baleenbird species which lives in large family groups. Its most distinctive trait are the keratinous spikes that cover the outer surface of its feeding chamber. These are flattened and hooked, and are surprisingly sharp, particularly when the animal strikes with force. Growing around four metres in length and half a ton in weight, they travel in pods for protection (usually around a dozen, but occasional super pods of nearly a hundred may occur in certain periods where food supplies can sustain them), but also utilize these spikes to defend themselves aggressively, mobbing and ramming larger enemies, often creating serious wounds or even killing their aggressor. Many older predaceous dolfinches and jetguppies that coexist with the species are covered in distinctive rows of scars from such experiences, lessons learned when young and unpracticed.
During times when their normal planktonic prey is scarce, dreadnought baleenbirds make a remarkable dietary shift. Aside from the normal brush-like bristles which adorn their feeding tentacles, they also possess hooked, blade-like projections running parallel on the inner surfaces that act like teeth. During periods of oceanic famine, dreadnought pods hunt larger, slower marine megafauna, the soft-bodied snarks, whale-like dolfinch species, even other baleenbird species, killing them through repeated ramming, or just using their "teeth" to shear off strips of skin and meat to graze off much larger animals without necessarily killing them (although they may die later from complications of these wounds). They are also effective scavengers of the massive floating carcasses, which are a rare, but valuable feast, cutting away thin pieces of meat away like a kitchen grater. By way of these adaptations, the species is flexible in its lifestyle to take advantage of available food stocks, and is well-adapted for hunting of large and minute prey, but not so well at the medium-sized prey in-between. Nonetheless, this ability to tackle a differing variety of food gives them an edge in uncertain times to come, as reliable food supplies will be increasingly uncommon.
The follow-up to the wormy mitten post, these would inhabit some, as yet hypothetical, future period of Serina's future (they were planned to exist like ten or so million years later).
Eh, no matter how much the descendants would differ from their ancestors, still, evolution works according to the same laws, and therefore, living in the same environment and occupying approximately the same niches, they will look very similar. I tend to remind me very strongly of cephalopods and, in part, stingrays.