Parasites of the Hothouse Giants

The walking mountains that dominant the landscape of Serinarcta have become moving ecosystems in and of themselves. A herd of gantuans or skulossi on the move is hundreds of tonnes of flesh, bone, and viscera, a near-endless banquet for countless parasites, which plague the behemoths far worse than any predator. Never before in Serina's history has such a diversity and size of parasites ever evolved before, as never before have potential hosts of such size and number never occurred on land. And over millions of years, not only have the parasites radiated in many species, but relationships have developed between them as they compete for resources feeding discretely upon beasts many thousands of times larger than them.

The beelzebirds are a genus of squick, no stranger to the life of a bloodsucker when the pickings used to be much smaller, and these have swelled to mammoth sizes (relatively speaking). The black beelzebird is the largest beelzebird species, with the male able to reach the size of a typical finch, enormous for a squick. In beelzebirds, males are much larger and more robustly built than females, for only the male is a primary feeder upon giant skuorcs. He has evolved a disproportionately massive head with a huge pickaxe-like beak for tearing through the thick, scaly hide of its host. Because its size makes it rather obvious to its host and potential predators, it feeds primarily at night when it is much harder to see it. The female is less than half the mass of the male, with a more normal beak, and feeds primarily on nectar and plant sap, supplementing this diet with blood from smaller animals, mostly thorngrazer species. The male's size is not merely the strength possessed to get at its food, but for the beelzebirds' reproductive strategy. Males stay with one animal as their host and are highly territorial towards it, actively defending it from other bloodsuckers, to maintain the health of their host. Females judge males as reproductive mates based on the health of their host and lack of markings made by other ectoparasites, and part of the courtship ritual to prove themselves to females involves the male cutting open the skuorc's skin to give her a nuptial gift of blood, both providing an honest signal of his host's health (allowing her to taste for any irregularities that could indicate blood-borne illness) and allowing her to replenish her nutrients from egg-laying.

Females glue numerous tiny eggs (anywhere from 5-12) to the male's underside and leave it up to him to open up cuts in the skin and deposit eggs into each individual wound for the young to hatch and incubate as larva, feeding quietly on flesh in a little warble, while she continues to seek out suitable males until she runs out of eggs. Then, it is up to him to protect the larvae from "cleaner" animals; the proliferation of parasites that infest giant skuorcs is now so extreme a proliferation of animals that feed primarily, or even solely, on parasites, including those which can dig under the skin to extract larvae which burrow within the flesh, just as a woodpecker can extract grubs that burrow under a tree's bark. The male's size and strength is formidable, required to defend his growing and hapless offspring from predators, even those much larger than it. Attacking ferociously with his huge beak and claws, the father devotes himself to this cause entirely, forgoing feeding and sleeping minimally. By the time the hatchlings have fed enough to drop out and pupate in the earth (usually around 3-4 weeks, he is almost certainly dead from stress, injury, or starvation. Very few males survive more than one breeding cycle, while females may survive for several years, outliving the males many times over. After metamorphosis, young males go through a subimago-like stage, initially being indistinguishable from females, only growing in size and changing shape over a period of a few months.

Beelzebirds are named due to a type of symbiont which they are commonly associated with, a type of tiny flying arachnid known as the sanguine midgemite, which commonly swarm around large animals. Their diet is primarily blood, but they come from a lineage with no piercing mouthparts and are not closely related to other parasitic flying mite species, and therefore rely on wounds created by injury or the work of larger blood-drinkers, sopping up the remnants. Being so small and utterly harmless, the beelzebirds ignore them, and they in fact provide a mild beneficial property. The saliva of the midgemite has antibiotic properties, helping to prevent infection as they feed on wounds, since the sickness would inevitably pass to them if they fed on a sick host, and is especially useful for preventing the host from weakening when infested with the numerous developing larvae (which can be up to 18 grams in weight close to maturation) of the squick. So, together with its territorial maintenance and its medicinal symbionts, the beelzebird, despite its utterly parasite and harmless lifestyle, is nonetheless among the least debilitating infestations a skuorc can come under. 

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Obligate parasitism as a lifestyle is one of extreme specialization, as the environment of a living animal is one unlike any other ecosystem, one that perpetually provides easily accessible sustenance but also actively attempts to rid itself of the freeloader. Many of the adaptations used for surviving the outside world are redundant or unnecessary By this metric, it should be no surprise that the squicks, a lineage of birds highly specialized over tens of millions of years for obligate parasitism, have become some of the most derived theropods to have ever lived, with forms scarcely even vertebrate in appearance. And of those, possibly the most freakish of any bird that has ever evolved are the ones which have managed to evolve to thrive deep within the viscera of another. Progressing from scavenging larva to skin-burrowing pests to creatures living much further into the flesh was not as drastic a progression as it may seem, as such adaptations occurred amongst invertebrates more than once.

Aside from their size, skuorcs are more susceptible to internal parasites than the thorngrazers, and, to a lesser extent, trunkos, that once dominated the ecology of Serinarcta because their digestive process is much more inefficient and their process of ingestion is crude, with no chewing involved, allowing oral intake of parasites to occur much more easily. The vast gut of a skuorc is enlarged; because there is no mechanical digestion of ingested matter, it relies almost entirely on extended bacterial fermentation in large gastric chambers to leech out absorbable nutrients in vegetation, meaning there is plenty of real estate. Squicks were able to migrate from life as a skin parasite to embedding themselves into the lining of the mouth, crop, stomach, and deeper reaches of the digestive system, feeding on blood or stealing semi-digested matter from their host, until they are eventually excreted naturally. Living inside an animal may require certain distinct adaptations, but it means they no longer need to worry about being dug out by parasite-eaters. This subgroup of squicks, known as flukebirds, are widespread amongst larger herbivores and omnivores, particularly skuorcs, and generally harmless unless in particularly heavy infestations in unlucky individuals. Most only spend part of life lifespan as gastric endoparasites, emerging in the dung as fattened larvae which burrow into the earth, pupate, and emerge as typical adult squicks.  Although, a few species have adapted to life almost permanently nestled deep inside the guts of another.

The skin of the flukebirds have numerous defences to avoid being digested, a very thin layer of translucent keratin (which most animals have difficulty processing) over a large portion of the skin, a constant secretion of mucus, and enzymes in the mucus which neutralize digestive juices. The bones of the rudimentary skeleton are almost entirely cartilaginous, the respiratory system is basically vestigial, and the digestive tract is simple. Most oxygen and nutrient intake occurs through folds of the permeable skin simply by diffusion, and the skin along the flanks is very loose and wrinkled to greatly increase surface area, allowing for a greater rate of osmosis. A hooked beak and clawed forelimbs are retained to keep the squick securely attached against the forces of peristalsis, for independent movement through the digestive organs, and for finding a suitable cocooning location once ejected to complete its metamorphosis. Since eyesight is useless, flukebirds have developed an enlarged vomeronasal organ-like structure at the base of the beak to detect changes in the chemical changes, other flukebirds, or competing parasites.

The viscerous flukebird is a particular species with massive sexual dimorphism, with the female having highly neotenous development, never naturally maturing past the fleshy, grub-like infantile stage of its life, only increasing in size greatly. Indeed, a full-grown viscerous flukebird female, capable of growing just over a foot long from vent to beak-tip, is the largest of all the squicks, although the male is much, much smaller than her. Both males and females begin their life-cycle similarly, developing in the stomach lining by feeding on blood; the female eventually migrates to the small intestine, where she latches on to a suitable spot in the gastrointestinal wall for the rest of her life, which can last for years. The male too, eventually migrates to the small intestine, but not to feed, to seek out a female. The male has particularly large and forked sensory organs to find her inside the intestine; necessary since he is stumbling totally blind inside an intestine can stretch for more than two-hundred feet. If no female can be detected, he can wait in a state of dormancy in a mucous chrysalis for several months until one shows up, and small spines along his arms give him extra grip for crawling through the bowels. The male will mount himself to the back of a female, his squeezing motions and the sensation of the small spines inducing the female to release an egg sac (numerous tiny jelly-like eggs within a thin membrane), which he grasps with his flattened curling tail, and carries with him as he then exists the digestive tract. When he burrows into the ground to pupate, he buries the eggs alongside him in the pupal chamber. Once he emerges as a mature feathered, flighted animal, he will fertilize and then ingest the egg sac, storing it in his crop (as he does not eat as an adult, his digestive system is now non-functional).

Some flukebirds deposit their dormant eggs on vegetation or carrion their preferred hosts are likely to ingest, or inside various well-used watering holes, in the hopes that some of the eggs will make their way into the suitable animal, but the viscerous flukebird has a more proactive dispersion technique. The male will fly directly onto a gantuan or skulossus, and loosely glue eggs onto its skin, targeting the back, neck, and forelimbs. Then the eggs will wait until they are accidentally ingested when the animal grooms itself (or, in skulossi, when a herd-mate grooms them) with its mouth, allowing them finally activate and hatch inside the stomach. Once the egg sac is emptied, the male viscerous flukebird will die of starvation, usually within one week of emergence. Males of some other flukebird species do feed after maturation and will live much longer (although just comparatively, up to a few months), searching out dung of their hosts to find other egg sacs to fertilize and carry off; the dung of infected hosts have a scent noticeable only to them, making potentially egg-containing faeces easier to find. This strategy is much more energy-intensive for the female as it includes the very high likelihood that many eggs are wasted, and requires males to manually search for eggs, resulting in a far greater uncertainty he will live to pass on his genes. While the viscerous flukebird has a more complex reproductive strategy and each male only insures one batch of progeny, the likelihood of young from this one batch succeeding to reach maturity is much more likely. 

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One of the most massive parasites that a skuorc can possible be afflicted with is a visceral monster that writhes and burrows beneath their scaly hides just as a mole tunnels through soil, ripping through flesh with a blade-like beak and huge claws. These are the parasitic offspring of the rasps - huge skewers, and now one of the largest verminfan clades: they are highly predaceous animals once full-grown. Adults find an unaware gantuan or skulossus and create a small incision to implant a small egg, repeating this process across every animal it can find. Over a period of months, the larvae slows develops, feeding on muscle tissue with horrendous vigour, using its radula-like toothed tongue to "lick" pathways through flesh. Infected animals are easily recognizable by the faint scarring patterns in the skin by the skewer infant's feeding underneath, and the huge pimple-like openings from where the larvae emerges periodically to take a breath. It is little mercy that the powerful immune systems of these animals, defensively honed over millions of years of ever worsening parasitic infections and predator attacks, usually allows them to weather this affliction. 

Burrowing several inches beneath the dermis, it is usually unreachable by pest-eaters and has free rein in its abode of flesh. Its tubular body is angled with numerous backward-facing bristles, and its soft skin is loose and elastic, to allow it to slide with ease through layers of muscle, pulled along by strong forelimbs, and hooking itself securely with its pick-like jointed beak tip (back legs are scrawny and don't play any role in locomotion at this stage). Although its feeding habits are quite painful to its host, its saliva contains mild neurotoxic and antibiotic compounds, dulling the discomfort and preventing infection, since it still requires its host to get through the experience alive so it can eventually pupate and emerge. Most of its underdeveloped skeleton is cartilaginous so it can squeeze its body through the layers of tissue (and prevent it from being harmed if its host happens to rub its side against a hard surface), while a low metabolism allows it to feed minimally and go hours on minimal oxygen (after all, there's no need to regulate one's body temperature when the host's body already does so). By the time the larva is ready to pupate, it can weigh almost as much as a human infant and be over forty centimetres in length, dwarfing in size any other parasite aside from some particularly lengthy gut worms; even should it be caught by a cleaner bird or other animal surfacing through the skin, it's so big that it can actually defend itself quite effectively against them.

Secreting a cocoon of mucus, it eventually emerges as a small feathered bird, no hint of its previous life as a grotesque grub-mole. Even after pupation the host is not necessarily freed from its torment, as the juvenile bird will continue to linger about like an oxpecker, becoming a flying parasite and, if anything, is an even bigger nuisance, picking at wounds or actively creating new wounds to continue feeding on the skuorc's flesh, with the cygnosaur unable to do much about it, and without even the dubious benefit of numbing and medicinal saliva to dull the aftereffects, now that the rasp has no pragmatic obligation to keep its host alive. Eventually, the rasp moves beyond grazing flesh as a nuisance to becoming an active predator as it grows large enough to reliably kill prey, sometimes larger than itself. Although the nature of its lifestyle changes dramatically over its lifespan, from the moment of hatching from a tiny egg up until its final maturity as a massive arboreal, it never forsakes the hunger for flesh by any means. 

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Skewers in general are well adapted to become parasites, with many sporting specialized sharp tongues in place of a lower jaw. Nightblades are a worldwide family of linialinguid skewers descended from tonguetwisters that are entirely carnivorous. Specifically, they are sanguivores, with a diet made up entirely of blood. Their origins began as pollinating insectivores which learned to use their sharp bills to puncture tick-like parasitic mites that clung to large hothouse herbivores, and then lapped up the vertebrate blood that had been stored in their bodies. But their time as helpful cleaner organisms was brief, because within only a few hundred thousand years they had adapted to get that tasty blood right at the source. The bill became narrow and extremely sharp on its top edge, and fine serrations appeared, allowing these animals to stab the necks, flanks, and bellies of larger animals - trunkos, thorngrazers, giraffowl, and especially giant skuorcs. Blood, though abundant in large victims, has low nutritional levels, and requires frequent and heavy consumption to sustain an animal eating nothing else. The nightblades thus evolved longer bills, letting them slice deeper and deeper wounds, which would bleed for hours. The birds would then be able to return to them continuously throughout the night, dodging defensive motions of their victim, returning any time it rested to stick a brush-like extensible tongue into the cut to suck up the liquids, retract it into the mouth hole to drink it off, and repeat. As birds reached their largest ever sizes on land in the later hothouse, in the form of gantuans like the cygnosaurs, and the closely related skulossi, so too have these parasites grown in turn. Nightblades now include the largest ever blood-sucking parasitic vertebrates on land: the barbarous nightblades, which can weigh up to 12 pounds and flies through the night in search of new victims on a four and a half foot wingspan. 

This is the only species not designed or illustrated by Troll Man on this entire page!

Barbarous nightblades are creatures of northern forests, often in damp areas. They are dependent on large old-growth trees with sufficient hollows to roost by day, and are rare in the drier south where cementrees dominate. They are strictly nocturnal and fly only by night, seeking out the prey by scent. Juveniles, which pupate after spending their larval period burrowing within vast piles of cygnosaur dung, emerge no bigger than sparrows and so can feed on a wide range of species, even birds as small and snoots and sparrowgulls. Adults, however, are so big as to be able to sustain themselves only on the very largest skuorcs, and further, due to their size, they are much more inclined to feed on skulossi rather than cygnosaurs, as the latter can defend themselves with whip-like tails that this species is less able to avoid the larger it grows. The barbarous nightblade is solitary and aggressive to its own species, each individual fighting off any other that approaches a feeding site, usually situated high on the lower back of a skulossus. Other species, however, are less noticed, and the deep, long-bleeding wounds produced by the barbarous nightblade are utilized by a wide range of smaller parasites as well as oppurtunists that are not sanguivores, but will not pass up the free meal to supplement their diet. As the nightblade comes and goes from a new feeding wound each night, flocks of smaller birds, including other skewers, as well as many insects and even some sparrowgulls visit the gash and drink their share, also assisting in keeping the cut open and bleeding throughout the night. Only by day, when the largest of all blood-sucking birds retires to roost, does the victim get some reprieve and a chance to heal. Though even then, diurnal verminfans and other pests which lay their eggs in wounds are then quick to take advantage of the injuries. Being so big comes with its own costs in the hothouse, and though the largest gantuans and their kin may have fewer large predators to worry about than smaller animals, they live a life of endless bites and cuts, being constantly eaten alive in small bites by animals so little in comparison that they can do little about it except endure. 

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Not all parasites are birds, of course. For though metamorphic birds are especially well-suited to these roles in the ecosystems, other small, creeping organisms have adapted to exploit the hothouse giants for food, too. The most diverse and speciose variety of snark is one which is not often considered, for it is often overlooked or elusive. This is the niche of parasitic snarks, which occur in untold thousands upon thousands of species, accounting for nearly half of all living snark species. This may seem unbelievable, but it has to do with an incredibly fast rate of evolutionary radiation accounting for the evolution and diversification of their hosts; as the host species evolve into multiple species, so too do its parasites, often several times over. Many snark species are themselves host to snark parasites, and some of these parasites are themselves host to even smaller hyperparasites. As well, the perpetually warm and moist climate of the hothouse has promoted the proliferation of sickness and disease like no other point in Serina's history, allowing them to spread across the globe and jump from host to host with ease; ultimately, snarks are just one of many parasitic animals which have benefited from these conditions.

Parasitism as a lifestyle has occurred several times independently in snark evolution, leading to the large assortment of shapes and sizes of them, and one of the newest groups to appear are pancake snarks, a type of amphibious ectoparasite descended from the creeping spikeray, able to survive long periods in drier conditions, a valuable attribute as the landscape has begun to change and less waterlogged environments have developed. With tough, scaly skin, they can survive for days out of the water, and muscular body allow them to actively crawl on land in search of hosts, something few other snark parasites have the capacity for. Their entire body has been transformed into a series of fleshy suction pads, including the fusion of the back appendages with the tail. Their transition to parasitism likely began similar to many parasitic animal species, starting off feeding passively on top of larger animals as a commensal or even beneficial hitchhiker, feeding off the small parasites that riddled the hides of larger animals, before eventually progressing to getting the parasites' original nutrition directly, becoming parasites themselves.

The life of a skin parasite isn't as easy as it might seem; because the market for this niche is booming, this has also incentivized the evolution of numerous cleaner animals which find a bountiful harvest in the sedentary, edible, blood-filled creepy-crawlers that carpet the bodies of large animals, beasts which happily give themselves up to these cleaners to be rid of their irritating infestations, however temporarily. All manner of parasite-eaters, both obligate and opportunistic, will peel the snarks from the host's skin and devour them, prompting the evolution of many characteristics that make this much more difficult.

A thick, adhesive mucus secreted from their underside forms a vacuum-tight seal along the edges of the body, tightly suctioning the snark to the host, while small hooked spines dig into the integument like velcro, and the curved mandibles pinch the flesh, in effect providing a triple assurance, making them exceptionally difficult to remove. Their smooth, flattened body lacks any potential holdfasts for predators, their stalked eyes can be completely retracted and their sensory tentacles folded underneath the body. Like many snarks, they can also change the hues of their skin, allowing them to closely resemble the colour and pattern of their host's skin, making it more difficult for cleaners to spot them. Because of these numerous specializations, they have quickly risen to great success in their niche, having already radiated into over twenty species within several million years.

The jumbo flapray is the very largest of the pancake snarks, for it has adapted to feed upon the very largest land animals to have ever existed on Serina: the great skuorc titans that roam the northern continent of Serinarcta. Capable of growing over fifty centimetres in length and nearly as wide (most other pancake snarks tend to be under twenty centimetres in length), they have exceptionally large, scalpel-thin mandibles capable of slicing through their thick hides, and can drain nearly two-hundred millilitres of blood in one sitting. For animals that often weigh well over ten tonnes, a single flapray is a minor irritant, but heavier infestations can severely weaken even a large adult, as they drain many litres of blood. Being so large, flaprays are quite difficult even for the most determined and specialized parasite-hunters to remove once feeding, but at the same time it makes them more vulnerable to predation and desiccation when not attached to a host. Between meals, the flapray will bury itself in moist earth, underneath rocks, or slip into murky water to prevent from being found while the bloated mollusc digests its meal. The flattened body lobes of the pancake snarks retain enough mobility for both crawling and underwater swimming, although not quite with the same finesse and speed as many other snarks.

Few animal groups explored the niche of parasitism with as much variety and vigour in the hothouse era than snarks, as the tropical global climate has opened up so many opportunities on land. On a single adult gantuan, there could be up to ten different species of snark feeding on its body at any time (and various other species of parasitic animals as well), ranging from tiny nematode-like animals smaller than a grain of rice inside the blood vessels, to whipping intestinal serpents as long as a python and flattened bloodsuckers wider than a dinner plate. The surface of a giant skuorc is almost like a walking banquet to cleaner animals, so many obliviously feeding grazers engorged with delicious, nutrient-rich blood, and so an arms-race has developed between the hardiest and most resilient parasites and their increasingly specialized predators.

The whistleworms are a recent group to make the jump to terrestrial parasitism, having evolved to exploit the perpetually humid climate and vast expansion of wetland environments during the hothouse era. This has helped facilitate a defence mechanism that works in this new medium. They normally dwell in ponds and streams, or, if the moisture is sufficiently high, under wet rocks and damp leaf litter. Its eyesight is poor, and it has even lost the stalk-eyed look of most other snarks, detecting potential hosts through other means, such as air vibrations, scent, and body heat, slithering towards their quarry quickly upon venturing within several feet of the lurking gastropod. Whistleworms which hunt on land are more active than those in the water, inching about in the dead of night, attempting to pick up the increased carbon dioxide levels in the air that denote a sleeping animal's exhalation. It is not uncommon for several whistleworms to hone in on a single host animal if such animal is particularly large. These animals range in size from an inch in length, to the largest species, the screaming whistleworm, a thirty centimetre-long monster capable of ingesting 25 millilitres of blood in a sitting, and spiked mandibles two inches long able to pierce the thickest skin, which most commonly infests the very largest possible hosts: giant skuorcs (although particularly large aquatic or semi-aquatic animals like sea horses or river dragons are also regular hosts).

A typical vermiform hematophage, it latches upon the skin of a host with three pairs of suckers along the underside of fin-like appendages. So many independent suckers makes it difficult to remove once attached, as well as making its body shape harder for predators to discern from a distance. When a predator attempts to peel the snark from the skin by unsticking each individual sucker gives the gastropod a chance to re-stick each unstuck sucker, hoping that it proves too much effort for a predator to deal with. If they attempt to pull or attack the snark directly, it unleashes the defence which gives them their name. Forcing air in its body through its narrowed spiracles, it lets out a series of piercing trills, while also inflating a pair of brightly coloured and patterned display structures, intending to startle any would-be hunter. Although it's just a bluff, a number of parasite-eater-eaters, like certain flapsnapper and skydart species, have learned to recognize the distinct distress call of the whistleworm, as it very often alerts them to the exact location of a possible prey animal at that moment, with both an auditory and a visual signal. For this reason, most cleaner animals may be inclined to give this particular parasite a wide berth. The fact that whistleworms have so many layers to their defences is a testament to the surprisingly harsh life of a bloodsucker and the cutthroat selective natural process which led to it.

All whistleworms begin their life small and independent, but are hemovores from birth, feeding off larger and larger hosts as they grow and mature. An unusual behaviour in the genus is the sharing of blood, primarily seen initiated by young snarks towards any adult snarks they may encounter. By rubbing their facial bristles against the face of another whistleworm, the stranger, if recently fed, may be persuaded to give up a small portion of their meal by regurgitation, tiding the beneficiary over for a little longer as it searches for its own host. Male whistleworms will also initiate courtship with a female by presenting her with a gift of a blood meal, which provides her with the additional energy required to produce young, as she will otherwise almost certainly reject him.

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Snarks by the late hothouse have diverged into countless different forms, ranging from burrowing worms only a few millimetres long, terrestrial forms waddling upon four tetrapod-like legs, up to vast pelagic hunters larger than a school bus. But perhaps what is most extreme in their ranks are not what they have advanced to, but what they can lose and still function, in an environment unlike that of other lineages. In this manner, the most unusual snarks would undoubtably be considered those of the endoparasitic variety, those which have taken up residence inside larger animals. These come in a surprising number of forms, as this adaptation has occurred more than once amongst snarks.

As a general rule, how large a parasite gets depends on the size of its host. On Earth, the largest tapeworms occur in the guts of whales, while the the biggest ever fleas plagued the hides of non-avian dinosaurs. Here, the rule works in the same terms, as the mega-skuorcs which roam Serinarcta are host to some truly gargantuan pests, inside and out. Their skin pulses with leech-like spikerays over a foot long, and botfly-like skewer larvae that grow larger than a fist, swarms of biting insects that could be mistaken as a flock of small birds. And their massive digestive tract, built for consuming vast quantities of vegetation, also writhes with intestinal parasites of repulsive scale. One of the very largest are the gutsuckers, creatures which resemble colossal nematodes, but are in fact a type of highly-degenerate snail, a breed of snark which have nearly lost all characteristics that define members of the group.

Gutsuckers originated, a bit surprisingly, as marine animals, simple detritivorous animals which thrived in the rich shallow seas feeding on bacteria, phytoplankton, and minute organic particles. Their transition to parasites originally began by accidental ingestion by herbivorous or filter-feeding dolfinches, and was subsequently carried inland by surf scooters, where it could then spread to land animals which drank tainted freshwater. The transition of a parasite from a fully aquatic host to a terrestrial one is obviously much quicker and more simple than for a full aquatic animal to become terrestrial, especially when both the original and new hosts are primarily herbivorous vertebrates. Primary hosts during the early hothouse were trunkos and thorngrazers, but as gantuans and skulossi grew larger and more common, they proved to be more suitable homes due to their larger sizes and proportionately larger digestive systems. Unlike either trunkos or thorngrazers, skuorcs have neither teeth or the cranial kinesis that allows them to chew, so food is swallowed in large chunks and digestion is primarily chemical, done by slow bacterial fermentation in a voluminous multi-chambered stomach and intestine. In total, their digestive tracts can stretch for several hundred feet, offering plenty of room for a veritable jungle of microfauna. The resulting nutritional chyme becomes a nigh-unending pre-digested feast for parasitic organisms that reside in its colon, allowing them to grow far larger than in these earlier hosts. 

The gutsucker has lost its own digestive system due to it being redundant for its lifestyle; its pharynx has greatly expanded into a large branching structure with which it passively absorbs passing nutrients into its bloodstream, and waste products are secreted through the skin. Its mandibles no longer serve any purpose in either food consumption or defence, and now curve backwards to act as holdfasts which cling to the gut wall. Because the amount of food which arrives each day is so immense and so little work is required by the gutsuckers to obtain it, they can grow enormous. The largest species, the bowel-lord gutsucker, can reach a monstrous eleven feet in length and up to fifteen pounds in weight for an adult female. Females are much larger than males, and also drastically differ in body shape. Males are much shorter and flatter, and retain small sensory tentacles. This is because females grow large to continuously produce large quantities of larva, while males merely need to find a female, curl themselves around her, and provide her with sperm, which are much less energy-intensive to produce. The female's right spiracle is much higher up than the left one to line up with the male's reproductive spiracle. Even the male's feeding tentacles are tiny compared to the female, because he actually gets most of his nutrients by parasitizing her, latching onto her back and siphoning up a portion of her blood.

Because they grow so large, only a relative number of them can take host inside a single skuorc at one time before it begins threatening the survival of their host. As a result, gutsuckers are territorial, and males will vigorously defend their females against other females which anchor themselves too close or rival males that attempt to usurp his place, tearing at them with hooked spines over his body (the females, once attached, do little other than feed and produce offspring). Once mature and with a male attached, females reproduce continuously until death; like all snarks, the gutsuckers give live birth, producing litters of tiny, maggot-like larvae about the size of a rice grain. These make their way to the cloaca, where they are deposited in dung and, depending on the species, either wait until they are washed into a nearby water source or cling to vegetation, waiting to be ingested. Some species have a secondary host in the form of the dungaroos, which naturally feed on gantuan faeces, and need to be ingested by this other skuorc species as well to complete their life-cycle. Young are born with simple eyespots and pigmented skin, as they will attempt to climb to light to increase the chance of being ingested by grazing animals, but these are both lost as they metamorphose into their adult form in the gut. 

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Not all invertebrate parasites, of course, are snarks. Many millions of years before the first canaries were ever seeded upon Serina's fertile eternal pastures, they and their fore-bearers and their fore-bearers' fore-bearers were inflicted by dermal parasitic mites, a pestilence that has followed them long since before the first birds even existed and continued to follow them in Serina's twilight, many hundreds of millions of years hence. No matter the form, size, or habitat, their parasites followed unerringly. The giant skuorcs are no exception, the loss of feathers and re-evolution of scaly skin was little issue, and their great sizes provided far more environment for them to proliferate. But it did present one challenge: with no shaggy integument to hide in, they were exposed to the elements, and of course predators, which swarm about the skuorcs endlessly, the countless parasites infesting their bodies allowing many species to specialize in cleaning them. And so began a strange sort of arms' race on this new sort of ecosystem, where even being a verminous leech is living life on the edge.

Glimmermites are a subgroup of ectoparasitic mite which do not suck blood, but feed on keratin, a substance most animals cannot effectively digest or derive nutrition from. At its base, keratin is constructed of protein chains, similar to flesh, but the polypetide bonds that create keratin are more difficult to break apart than other protein types, and keratin occurs in far smaller quantities in an animal, so fewer animals are adapted to subsist on it. For diminutive invertebrates like mites or insects, the relatively small amount of keratin available is no issue due to them already being very small, and with many other ectoparasites of skuorcs already specialized to consume the host's blood or flesh, at least a few groups have avoided competition with them by subsisting on the scaly skin surface itself, as well the spines, osteoderms, and quills that erupt from it in many giant skuorc species. Digestive enzymes secreted through their saliva help break down the keratin between being scraped up by mandible-like pedipalps. Although, glimmermites will also feed opportunistically from open wounds, or incisions created by specialized blood-drinking parasites able to open up the host's thick hide. The opaline glimmermite is a typical species, noted for its dark shell that shimmers bluish-purple, and can reach up to two centimetres in diameter.

In normal population densities, the glimmermites are largely harmless, as they don't naturally spread disease as many hematophagous micropredators do and they are so small that what damage they do individually is entirely negligible. However, as mites, they are naturally prolific breeders, with females producing up to five eggs in a single day, every day for their entire adults lives, and can easily overgraze, causing mange-like conditions and irregular shedding. Afflicted skuorcs can be easily recognized by patches of skin stripped down to the underlying pink dermis, which often become inflamed and infected due to secondary stresses by exposure, which is itself obviously visible by reddish bruising, oozing pus, and pimples around the overgrazed skin patches. The glimmermites' habit of feeding on already opened wounds and feeding on scabs also impedes healing and can expose their hosts to disease far more frequently. Other, more harmful ectoparasites often take advantage of overgrazed patches to more easily access blood vessels and muscle tissue and themselves proliferate, meaning the glimmermites can cause a cascade effect leading to poor health in their host if their numbers are left unchecked, even if they are just a minor irritant at worst by themselves.

Adult glimmermites are rather difficult to remove due to their namesake hard shells, a single sheet of glossy chitin which covers their entire bodies like an impenetrable shield. The edge of this carapace is serrated, allowing the mite to wedge itself into the grooves and irregularities of the skin, which, along with its strongly hooked feet, make it nearly impossible to extract by cleaning animals, while the shell itself is completely smooth, making it just as impossible to grip. This carapace is constructed of several compressed layers of zigzagged chitin fibres, rendering it extraordinarily durable, preventing it from being easily pierced by distributing the forces exerted on a single point across the entire surface. The adults are therefore much more well-defended against predators than a basic skin mite (although they can still be caught by especially quick cleaning animals before they can anchor themselves), rendering a well-established colony very difficult indeed to be rid of. However, their larvae are much more vulnerable, as their carapace is much less durable and they cannot hold as strong a grip as the adults. This is compensated for by their sheer numbers and their much more cryptic colouration, but the adults, which otherwise completely ignore the larvae and nymphs, do have another defence to help their offspring reach maturity (which takes about three weeks from hatching).

The mites get their name from their brilliantly iridescent shells, which are used for visual communication. But not between members of their own species, as their vision is poor and they cannot even discern colour, relying primarily on sensory hairs for navigation. Its bright bands of mesmerizing colour and highly reflective surface make the carapace easily noticeable even from some distance (a skuorc with a heavy infestation often looks like it's glittering all over), and this attracts the attention of another sort of arthropod, which knows what it signals. Vespers, a sort of wasp-like flying ant, which are attracted to the twinkling of the adult mites, and help guard the vulnerable larvae from predators with their venomous stings. In exchange, they can nudge the larvae to make them excrete a fat-rich lipid emulsion that the vespers use for sustenance and feed to their own larvae, a reward that makes guarding the young of a completely unrelated species worth it to the insects, although it is completely unhelpful to the unfortunate skuorc, which would surely want nothing more than to be rid of the mites. The biggest threat to glimmermites is actually even smaller hyperparasitic mites, which can decimate them given the proper conditions, something that is much more likely when their population density is higher, and so keeping their numbers in check in a complex web of ecological interactions. 

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Although there are many strange varieties of unique parasites on Serina, nonetheless the most numerous and virulent animal parasites are still the expected varieties that plague life on Earth, mites and nematodes. This is not to say unique varieties of these have not appeared on Serina in its nearly three-hundred million year legacy as a life-bearing world, indeed they proliferated and diversified at every bit the rate of the more charismatic vertebrates that more obviously dominate the lands and sea. One of the most fantastic of such adaptational radiations was the development of true powered flight within a lineage of hopping mites in the mid-Pangeacene, something which had only appeared amongst all invertebrates once before. These wings, comprised of numerous flattened and overlapping hairs growing from the third pair of legs, were crude at first, but improved over innumerable generations to the point they are as fast and maneuverable in the air as any insect. As is universally the case for animal groups which develop true flight, it ushered in a grand explosion of diversity, no doubt helped by a far smaller diversity of insects and other arthropods on Serina, allowing these mites to fill many niches filled on Earth by flying insects.

While on Earth, herds of megafauna are reliably plagued by swarms of biting flies, on Serina, an arguably even worse variety of biting arthropod has evolved, the quite self-explanatory tickflies, a group of hemovorous flying mites. Blade-like pedipalps, honed to a microscopically-thin edge, slice through layers of skin to get at the blood vessels underneath, which are then pierced by saw-like chelicerae, with anticoagulant secretions to keep the wound bleeding for longer while the arachnid drinks its fill. Although the top of its body is a rigid carapace, the underside is much softer and more flexible, allowing its gut to expand greatly in volume to accommodate a large meal; a tickfly post-feeding may weigh more than twice as much as it did beforehand.

The sacral tickcada is a species notable for its unusual lifecycle and sexual dimorphism; like many arthropods, particularly insects, the females are much larger than the males and flightless (although they retain small wings, which are modified into display organs). They are also primarily herbivorous, feeding on plant sap and fruit juices from trees, unlike the blood-drinking males, and has only small pedipalps for climbing with. This is because males provide the females with meals of regurgitated blood as part of their courtship ritual, which supplies the protein needed to produce large quantities of eggs. As females are cryptically patterned as camouflage against insectivorous predators, they flash their brightly-coloured wings, normally hidden beneath their carapace, and use them to fan pheromones into the air, which signals their presence and sexual availability to any males nearby. Females produce large clutches of egg sacs throughout their adult life, and these will very frequently be inseminated by sperm from multiple different males, which helps ensure the genetic diversity of the species, as egg sacs are always heavily skewed towards male offspring, due to the sex roles of the species.

The larvae are burrowing detritivores, hatching only a few millimetres long, spending the first few months of their life growing and moulting unseen beneath soil and leaf litter in more forested regions from where the females deposited their eggs. Males emerge and moult into their imago form en masse, usually after the first heavy rain of the season. Typically, there are two, sometimes three, emergences per year, although the timing of these emergences varies by tickada populations and weather conditions across the continent, so it's possible for migratory animals to have the misfortune of experiencing them more often than two or three times a year. Broods time their emergence to within 48 hours of each other, and soon black clouds of them, many hundreds of millions strong and stretching in congregations tens of kilometres wide, descend upon the savannah, forming a dark haze over the land, the beating of billions of wings together audible for miles around, like a horde of vampiric locusts. For a period of about two weeks, they feed and mate as much as possible; their occurrences every bit as destructive to life as the mega-hurricanes and super-monsoons that periodically devastate the lands. Although there are several tickada species, this is by far the most numerous, widely dispersed, and largest (up to an inch in body length for males), for it has adapted to feed on the bodies of the giant skuorcs roaming across the prairies, while the other species feed on smaller animals in the denser forest.

Particularly long and broad wings for a tickada allow them to soar hundreds of miles across the savannah in search of warm-blooded megafauna and return to tree cover to give its meals to a receptive female. Such huge numbers of the tickflies are a massive detriment to grazers and promote a huge increase of both blood-borne sicknesses and post-feeding secondary infections from the incisions the tickflies make, or simply anemia from the great quantities of blood being consumed or lost; healthy gantuans and skulossus adults can generally weather this onslaught, although they often lose several gallons of blood in these events, but smaller animals may actually die of blood loss if caught out in the open in the tickada clouds, as the arachnids cover every part of their exposed skin in the rush to feed as much and as quickly as they can, and continue to carpet even on their freshly dead corpses, as long as warm blood continues to fill their veins. The distant impending drone of the countless ravenous arachnids approaching can send animals of all kind to stampede for cover, as it's not unheard of for entire herds to be wiped out by the mites. For insect-eaters, this occurrence on the other hand, this is an endless deluxe banquet, as the bloated male tickcadas are easy prey, but their occurrence in such vast quantities ensures predation makes little impact on the overall population, as well as additionally crowding out competing micropredators simply through sheer numbers.

Either through eventual stress, predation, or other means, the hordes gradually dissipate as the males die off. Females take much longer to mature and live much longer overall; while the male completes its lifespan within four to six months, the female can last over eight years, living through many swarming events and producing hundreds of thousands of offspring over her life; during the peak of a swarming event, a female can lay egg sacs totalling over two-thousand eggs in a single day. Unlike the highly gregarious males, females are solitary, defending their thickets from other females in aggressive shoving contests. Although the ability to fertilize egg clutches with multiple sperm sources frees the males from competition during their very brief adult lives, mating as frequently as possible increases the chances that more of the resulting offspring in the next generation belong to those with greater mating success in the earlier swarm.