Snarks of the Mid Ultimocene

This guest entry was written and illustrated by Troll Man

Periodically, gastropods have swelled to huge sizes and diversity on Serina; in the world’s earliest days, they were the largest animals to live on the planet, millions of years before birds would escalate in size to outpace them. From the first mega land snails in the first millennia, to huge colourful grazers of the seagrass meadows, bird-eating arboreal terrors, massive spiralling reefs of sessile colonials, and beyond. Even so many epochs later, molluscs of immense scale continue to thrive during the waning days of the world’s lifecycle, and none reach scales more immense than the aquatic snarks, the cephalopod-like descendants of pond snails which have swallowed up the shell of their ancestors for a much more flexible and streamlined body form. Although many are of more modest sizes, snarks do include within their ranks the largest invertebrates that have ever and will ever evolve on this world, multi-ton beasts with fins several metres across. Although they originally evolved from benthic sea snails during the Cryocene, it was not until after the end-Thermocene extinction event that they began evolving spectacular forms. In the millions of years since, they have continued radiating into a myriad of strange and diverse forms competing directly alongside vertebrate fish and birds.

above: a wide variety of Mid Ultimocene oceanic snark species. Click here for full resolution.

Shaggy Spikeray (Setosoteuthoides arenatovenator): Although the image of huge manta-like swimmers may often be what comes to mind with the image of snarks, the vast majority of species were, and still are, benthic predators. Creatures that drift over the seafloor in search of prey, scouring the sands for organic detritus, or lurking beneath the surface and waiting for small animals that wander within reach. Of these three categories, the shaggy spikeray falls into the last one, with a ragged and extremely flattened body that it uses to hide its body. The snark's vaguely rectangular form is not at all streamlined, but for a bottom-dwelling ambush predator, it does not need to be. Its camouflage is honed from multiple tried and true strategies; a serrated frill-like edge to its irregularly shaped body prevent its silhouette from being easily recognized, with skin pigment changes further distorting its appearance through false shadows and visual assimilation with its environment, adapting into different surroundings as necessary.

Spikerays are so named because the males have adapted their bladed penis into a defensive stinger with toxic mucus, which can stretch up to three feet long to reach around its body. The chitinous tip is serrated and often breaks off when it stabs into a predator, increasing the risk of infection on the wound site, and will regrow within a few weeks. Females obviously lack this feature, but are nonetheless partly protected by their near-identical resemblance to males, an unusual case of Batesian mimicry present within a single species (spikerays as a rule therefore have no external sexual dimorphism). The shaggy spikeray is a well-camouflaged ambush predator and so utilizes this stinger rarely, never using it to capture prey, which is instantly swallowed by a voluminous mouth that opens and expands in a fraction of a second to vacuum small animals in (its mandible-like radulae are useful more for post-capture prey mastication). Since the stinger often breaks when used and has a vital reproductive purpose, it is too valuable to be utilized for routine hunting.

The shaggy spikeray is one of the larger spikeray species, with a broad body up to eight feet long and nearly six feet wide. Because most of its body is boneless and elastic, it can swallow animals up to a third of its body weight whole. Although generally a sedentary animal, it can glide through the water with little effort with a few sweeps of its expansive front fins, which it will do when it searches for mates. Like most snarks, they give live birth and provide postnatal parental care. Spikerays, like most snarks, are mouthbrooders, keeping the young hidden in their expansive mouths for several weeks after birth, and have evolved a milk-like secretion on the inner lining derived from epidermal mucus which their offspring subsist solely on during their infancy. This is not only rich in nutrients, but passes vital immune-building microorganisms from parent to offspring to make them resistant to infectious disease. During this period, the mother stops feeding entirely as the young snarks quadruple in weight. Even after gaining relative independence and learning to feed themselves, they will retreat to their mother’s mouth when threatened by predators for an additional few weeks before leaving fully.

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Eremite Snark: When snarks first evolved into fast-swimming and streamlined benthic animals, they sacrificed the ancestral shell of their snail predecessor, which has become internalized as a cuttlebone-like pen that provides little in the way of defence, existing only to stabilize the body structure. This was of little overall consequence, as they certainly many other defences to compensate over millions of years including venomous stingers, poisonous flesh, powerful and razor-sharp mandibles, and nearly seamless camouflaging skills, among other strategies, but one subgroup of snarks has gone back to the very basics. The eremite snarks use the shells of other marine snails as their own, either by taking abandoned shells of deceased animals or actively hunting down appropriately sized snails as prey, consuming them, and then moving into the recently-vacated home.

The body of the eremite snarks have adapted to suit this lifestyle; the two pairs swimming fins of its original ancestor have been modified into thicker and shorter shuffling appendages that allow the gastropods to drag themselves about on the seafloor, and much more quickly than the mono-footed slithering of regular snails at that. The tail has been modified into additional pairs of flattened, sucker-like lobes which allow the snark to cling securely to the inside of the shell and makes them difficult to remove by force. Some eremite snarks may plug up the entrance of their shell with debris, like rocks or smaller shells, while others simply rely on a vicious bite as a last resort defence against predators, which, ironically enough, most often tend to be other snarks, such as spikerays. The purple eremite snark (Domopraereptor purpureus) merely relies on what little shell it has as the plug if it needs to retract its body. Its mantle can inflate with water to wedge the snark into its shell completely, which, along with its suction-cupped, makes it virtually impossible to pull out.

Eremite snarks will often decorate their abodes with all manner of symbiont organisms or use mucous secretions to glue foreign objects to their shells to increase its durability or disguise its shape further. Preferred strategies vary from species to species, from planting of small kelps, minute symbiotic isopods, barnacle-like sessile snails, or the shells of prey animals. The purple eremite snark has a preference for colonies of stinging, sea anemone-like marine hydras for its protective decorations. These decorations are also vital in mate choices, as females will judge males by the quality of their homes and his exterior design. The eremite snarks often dwell in loose congregations that may be dozens strong; smaller individuals benefit by taking the discarded shells of older animals as they swap shells. Young snarks will retreat into the shell of their mother for the first few weeks of their lives before they grow more independent and obtain shells of their own, sometimes taking their parent’s own smaller collected shells as their first homes.

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Kelpcrawler (Phyllohirudo hematophagus): Although some species may consume small quantities of algae, nearly all snarks are primarily, if not entirely, carnivorous. Not all snarks, however, are actively predatory. Some have evolved into parasites, preying upon living hosts without necessarily killing them. The most common form of this is hematophagous ectoparasitism, exemplified by the leech-like kelpcrawlers. These small, flatworm-like snarks (usually between two and three inches long) cling to fronds of seaweed, either the tall, rooted, kelp-like fronds or free-floating sargassum-like masses which crowd the water column, blending in perfectly with their ragged bodies and dark green colour, and wait for a suitable pelagic host to swim just close enough for it to quickly hitch itself to them. Sticky, suction cup-like pads on the underside of its body anchors it securely to the host as it rapidly changes colour to match the skin tone of its specific victim.

Scalp-fine mandibles slice a thin incision through the skin and fat layers, allowing the extendable proboscis to reach the blood vessels below, and an anticoagulant secretion prevents the wound from clotting. If allowed to, the kelpcrawler can consume nearly three times its body weight in blood over several hours before it drops off again. Its primary limiters are cleaner animals, crustaceans, fish, and even some seabirds which specialize in ridding larger animals of ectoparasites; its camouflage helps it remain undetected by cleaners, but if it detects a cleaning in progress, it will quickly detach and swim off, sometimes sacrificing a lobe if necessary (which, as expected for a mollusc, can regrow over a period of a few weeks). Individually, kelpcrawlers rarely pose any significant risks to the health of their host (there is some risk of indirect infection when it drops off leaves the incision site exposed), but heavy infestations may both slow the movement of the animal and result in hazardous blood loss; it’s not unheard of for particularly unlucky animals to suffer under a few dozen of the parasitic snarks at once.

Most victims of the kelpcrawler tend to be marine tetrapods (or tripods), more often than fish, such as dolfinches, sealumps, burdles, and clamcrackers, which tend to grow larger and are less affected by their feeding. Fortunately, they only need to feed once every three or four months, going into a state of reduced metabolism for a long period after a feeding to digest its meal, relying on their camouflage to remain undetected during this period. Males which have fed recently may also devote part of this time searching for receptive females, which can certainly take a while when they blend in so well with their environment. Parental care in parasitic species tends to be more limited than in most snarks, and the kelpcrawler is little different. The kelpcrawler deposits its young on the seafloor near the den of a benthic snark species, such as a spikeray or sandgrabber, where it will disguise itself as the young of that species. The host parent will take in this brood parasite unwittingly, but they are relatively harmless to their surrogate family, only freeloading off of the food provided by the parent, and leave within a few weeks as the growth rate of the other young snarks surpasses it and its adult feeding mandibles grow in.

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Shimmershiner (Arcopterolimax regalis): Millions of years ago, the vast wings of the great trawler snarks shadowed the water; invertebrates on a scale unmatched before or since. In the turmoils of severe climactic and ecological shifts since then, the great trawlers have succumb to the march of time, but in their extinction, new filter-feeding pelagic snarks have evolved independently. While these may not be nearly as grand in scale as their predecessors, the sight of their great shoals moving just beneath the surface is awe-inspiring all the same. These are evolved from the benthic spikerays, but with stronger and more muscular fins for sustained and long-distanced powered swimming, curved for hydrodynamic movement through the shallow seas.

Moving in great schools hundreds, sometimes thousands, strong, the four-finned shimmershiners are the jewels of the open ocean. Growing between seven and ten feet in wingspan, these are to the open waters of the sea as herds of trunkos and antlears would have been on land in warmer times millennia ago, wandering nomadically, their comb-like radula sifting vast quantities of plankton from the water column every day. A large shoal can consume dozens of tons of plankton each day, converting it into waste that filters down into the seabed, seeding benthic ecosystems with organic detritus and helping to fertilize the endless underwater prairies of sea bamboo and plant-like algae, contributing immensely to the cycling of nutrients. In a sense, they are giving back to the ecosystem from which they originated, although not consciously of course.

The shimmershiners are intensely social, constantly maintaining contact and passing along messages between schoolmates by ripples of distinct pigment pulses on their dorsal side. They communicate visually, with specific flashing patterns signalling greetings, signs of affection or dislike, detection of danger, or relaying a turn of course. Group signals from the beginning of the shoal move downward like an undulating wave of glittering movement. The most awe-inspiring display of these huge pelagic gastropods is their defensive threat display. The entire shoal will begin a dazzling spectacle of banded rippling along their hides, a hypnotic and synchronized display that can stretch for over a hundred metres. This makes it both more difficult for predators to single out any one member of the group and is often intimidating enough on its own to get them to back down, perhaps fearing the possibility that what they believed was a group of individuals was actually a single gargantuan sea beast far larger than them. Shimmershiners have lost the toxic spines of their spikeray ancestors, and rely on their numbers and bulk as adults for defence; if necessary, they will swat at attackers with their wings or mob them with bludgeoning body strikes.

Very unusually for mollusks, they pair-bond and raise their offspring communally, having adapted heavily for K-type reproduction and only birthing one to three babies in a breeding cycle. Females in a shoal tend to time their births to within a few weeks of one another, and have little regard for whether the offspring in a group is their own or a schoolmate’s, readily welcoming any infant into their brood mouth. Shimmershiners migrate to open waters along the rim of the Icebox Seaway to give birth where fewer predators dwell, allowing their infants to grow in a relatively safer environment for the first few weeks of their lives, before eventually being forced to migrate back as the fat stores of their parent are depleted. Precocious and curious, young shimmershiners are highly mobile from the moment of birth, frolicking and dancing with one another within the relative safety of their shoals, and often take years to fully gain independence.

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Streamertail Snark (Virosfugax luminosaltator): Evolution, as it is often clarified, is without destination or direction; adaptations appear for their role best suited for an organism’s survival at the present moment, and are discarded once they no longer serve that purpose necessarily. It is from this principle that shell-less eremite snarks evolved; a gastropod which lost its shell, then (in a sense) regained a shell, and now has lost its shell once more. This is derived from their diet; they prey primarily on jellyfish and sea anemone-like hydras, and like some Earth nudibranchs, take on their venomous nematocysts into their own flesh. This is signaled by their vibrant colouration and garish patterning, a clear and honest signal of their extreme toxicity, concentrated to a degree that makes it far more potent than its prey. The fleshy suction pads that once allowed its shell-dwelling ancestors to securely adhere to the inner walls have been modified into more stiffened display lobes coated in their intensely poisonous secretions.

Their colouration also serves a secondary, but equally important function of display; as males compete vigorously attempting to create the most intense show of their vibrancy to impress females. The flattened posterior lobes that lined the tail of its shell-dwelling ancestor have been modified into a trailing tail which functions like the train of a peacock; receptive males flush their tail lobes with colour in gaudy shows that can last hours to entice females. Although both sexes possess strongly contrasting aposematic colouration to signify their lethality, males are far more garish and vibrant than females, for they are much pickier and harder to impress than potential snark predators. The tails of males are much larger than those of females; at up to five feet long, they are nearly twice the length of the rest of the body, while those of females are closer to half that length, since it only needs to be good enough to warn potential predators (however, females tend to be considerably wider and more heavily built, so despite their difference in body length generally weigh the same as males).

While normally solitary, males congregate to form lekking arenas during mating season, allowing females to closely compare the appearances and performances of each one together. This process is quite physically taxing for the males, who spends days displaying without feeding in the hopes of mating, and many will die of exhaustion and starvation by the period’s end. This helps ensure the strongest males mate most often, and also reduces competition for food for the next generation of streamertails. The venom of the streamertail is so potent, they run the risk of accidentally poisoning each other during mating, so the males have an exceptionally long and flexible penis to inseminate the female through minimal body contact.

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Spiny Spikeray (Acanthoptera echinatus): Although outwardly slug-like in morphology, it should be reminded that snarks have not lost all traces of their original shell. It has been retained in practically all species as a bony structure analogous to the gladius or cuttlebone of cephalopods. This allows the snarks to retain their body shape and greater strength at larger sizes as well as assisting with buoyancy, but in some species this serves further function in anti-predator defence as a sort of semi-shell, or has developed into greater complexity beyond simply a calcified rod to support snarks of aberrant lifestyles. The spiny spikeray is noted for the chitinous extensions of this internal shell which protrude from its upper body as dotted spines a few centimetres in height (these are retained in the closely related shimmershiners as well, likely from a common ancestor, but are largely vestigial there).

These taper to fine points which are quite brittle and easily break off, getting stuck in whatever they pierce like the quills of a porcupine. This passive defence allows the spikeray to avoid using its stinger and wasting its limited supply of venom and is particularly effective at guarding against a major snark predator, the snaggletooth sunseeker, which uses its bony head to press down on the snarks’ heads to prevent them from being able to bite or fire their stingers. With these spines, the sunseeker is unable to press down on the spikeray without injuring itself in the process. The defence is less effective against some aquatic avian hunters, such as dolfinches, which have a hard beak that is not so easily injured by these spines. But in this area the spikerays protect themselves via their colour-changing camouflage, as the snaggletooth sunseeker uncovers hiding snarks through hypersensitive touch nodules covering its face, while avian predators rely almost entirely on vision.

The spiny spikeray itself also preys upon benthic, sand-dwelling animals (a standard diet for most snarks); specifically it hunts small burrowing creatures which it unearths with a highly extendable mouth. This proboscis is very fleshy and can stretch up to seventy centimetres in length; fully extended it resembles an elephant’s trunk, allowing it to reach deep into narrow crevices and tunnels and pull out worms, small crustaceans, and eel-like fish. The action itself is very quick, normally no more than a few seconds, with most of that time spent “tasting” the rim of the burrow to determine if there’s a fresh scent, and then shooting its extendable proboscis into the hole to evacuate any living thing inside of it in an instant, before it can put up a fight. This is then retracted just as quickly and any prey sucked into the pharynx to be cut up by tooth-like radula projections. As this spikeray actively seeks out prey rather than lie in wait, it has more hydrodynamic fins for cruising low over the seabed, sometimes in small shoals.

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Sandgrabber (Dolichophis communis): More than one of the potential prey species of the spiny spikeray are other smaller snarks, but the sandgrabber is one which the spiny spikeray would be unlikely to accidentally stumble across. A polychaete-like tunneller, it has huge scissor-like mandibles held open by elastic jaw muscles, and when released these snap shut with tremendous force, almost certainly killing or irreparably maiming any prey caught in them. For any unfortunate spikeray, this would usually not kill them but it would surely be a very unpleasant experience as the sandgrabber instinctively snaps down on the nosey proboscis entering its lair. At up to five feet in length, this is a formidable predator capable of capturing and killing prey nearly as large as itself.

Although a primarily solitary hunter, it is often found in congregations that can stretch for dozens of square metres and comprise more than a hundred adult animals. These loose colonies serve several beneficial purposes, serving to crowd out similar predators in the same niches, being spaced to exploit food resources with greater efficiency, and, in a display of clear intelligence, they can mooch off of neighbouring snarks when their own hunting is going poorly, under the unspoken assumption that the neighbour will be allowed the same in a hypothetical future. After eating its fill (their slicing mandibles are not used in consumption, and sand grabbers eat by rasping with multiple rows of curved teeth which can be everted from the pharynx in a manner like a hagfish), sandgrabbers which arrive and display submissive behaviour will usually be allowed to consume whatever is left. This altruism also prevents food waste, as all parts of a carcass can be completely consumed in a single sitting. The underside of their front fins can flush with colours to communicate with one another, since, like most snarks, they are visual hunters.

This a seasonally monogamous species of snark, with males and females pairing up for two to three months of the year to rear young. Females have relatively large broods of up to twenty young, which are brightly banded to make recognition by adults easy. The infants dwell around and in the burrows of the parent snarks in creches, although they will retreat to their mouths if danger arises (which can expand to accommodate them). Young snarks scavenge on carcasses of prey captured by their parents and other snarks, but gradually learn hunt for themselves soon after birth. Neighbouring sandgrabbers are tolerant of young from their neighbours, which decreases overall infant mortality but inadvertently makes them more susceptible to brood parasites.

While such complex social behaviour and intense postnatal care are certainly exceptional among molluscs, it evolved merely as an extension of initial parental instincts present in the ancestral snark species during the Cryocene. Snarks as a general rule are K-strategist breeders, especially compared to average molluscs, and smaller clutches of young go hand in hand with increased investment in ensuring their survival. This formed the basis of the increasing intelligence and complex behaviours in future members of the group over many millions of years, as different species spread into different niches, evolving all new strategies of sustaining their young. Over this time, as such cooperative protection proved beneficial for the longterm survival of species (particularly in highly productive environments), more than a few lineages developed advanced sociality to compete alongside aquatic vertebrates in similar niches.

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Not all snarks are confined to the sea - their original ancestors arrived to the ocean waters from humble pond snails after all - and many have returned to the freshwater ecosystems from which they came. Though continued advancement of the glaciers over the continents have wiped clear many of the inland biotic communities, in one location near the equator, the climate has remained stable and temperate, and here, snarks continue to proliferate into freshwater ecosystems... and beyond.