The Sub-Arcuterran Cavern System, with all its strange flora and fauna, is remarkable for its unusual ecosystem that has flourished in darkness. Yet it is not alone: other lightless worlds too are found on HP-02017 in the Middle Temperocene, smaller and less-derived, but ones still harboring endemic ecosystems found nowhere else on the planet.
One such environment is Deeproost Cave, of northeast Gestaltia, a small, subterranean pocket formed at the base of the mountain ranges that formed at the base of the landmass that once was Fissor in the Therocene, before the landmasses fused together once again. Here, where melting snows from the mountains formed valleys and channels as its streams flowed downhill, a small pocket was carved through the rock, forming a cave system underneath that is run through by its own underground river.
Yet it is a very different world than the Sub-Arcuterran Cavern System, in spite of its similarities. Unlike the Arcuterran caves' self-contained environment, nourished by chemosynthetic bacteria that formed symbiotic relationships with shroomors and fungi to create the mocklichens and meatmoss that form the base of the entire food web, the Deeproost Cave ecosystem's main source of energy is delivered to it from the outside by air: in the form of ratbat droppings.
Not quite as cut off from the outside world as the Sub-Arcuterran Cavern System, Deeproost Cave is home to millions of nocturnal ratbats known as dingbats: which emerge at dusk in great numbers to forage at night and Beta-twilight and return to the caves by day to rest and sleep. Here, dingbats of various species, from tiny insectivores to larger frugivores, deposit large quantities of nutrient-rich droppings that blanket the cave floor and wash down to the deeper levels of the cave by rain and water currents: making life possible for the permanent residents who never venture outside.
Cave slingtails (Caudipodius subterrasaltus), small descendants of springtails, feed on the filamentous fungi that grow on the layers of nitrogen-rich droppings, while guano rollbugs (Subterrascarabus guanophilus), cavern-dwelling beetles, gorge themselves on the droppings directly, rolling small balls of it away to consume later, or using them as larders to lay their eggs on as a ready-made meal for their larvae. In the underground river, these nutrient-rich runoffs reach the water too, with small shrish such as the fan-feelered aquedart (Plumantenna subterraqua) using its long, brush-like antennae to forage for detritus that gathers at the bottom of the riverbed, and the thin films of bacterial growth that grows on rock surfaces or forms on the surface of some of the more stagnant parts.
A rather unexpected denizen of the cave are ants, likely descended from some queens and drones that had been swept down into the caverns by wind and rain, survived, and adapted to live in the darkness. Yellow-headed cave ants (Troglomyrmex anopthalmus) live in small colonies of a hundred or so individuals, where they farm their primary source of food, a fungus known as cavern puffmold (Cavernophyton cultivatum), on especially-tended beds of ratbat droppings. Worker ants tend to their fungus gardens, foraging for fresh guano to bring back to their nests to nourish the fungus, which then grows edible fruiting bodies that they harvest for food. Like most of the cave's other permanent residents, the cave ants are blind and have no eyes, relying instead on sensitive, finely-honed senses of touch and smell to navigate their surroundings, locate pheromone trails and recognize other members of the colony.
Yet one surprising exception not only subverts this trend, but inverts it. While the cave is in constant darkness, it is not total, pitch-black darkness, as some miniscule light from the surface and outside reaches in from its openings. As such, the sole permanent resident vertebrate of the cave, the gloomgoozler (Troglosauromys macroculus), a tiny basal rattile only a few centimeters in length, has gone the complete opposite route as the daggoths of Arcuterra: rather than losing its eyes or shrinking them down to atrophy, it instead evolved proportionally huge eyes, each one bigger than its brain, to capture and process what meager light is present. This gives it an advantage over its sightless insect prey, as it can locate them from a distance while its quarry is oblivious of its approach. Long, flattened digits on all its limbs maximize the surface area in contact with smooth, slippery surfaces, allowing it to climb smooth cavern walls with little difficulty as it prowls the caves in search of its next meal.
Like all endemic cave specialists, the gloomgoozler's populations are never too plentiful: only numbering about a thousand individuals at any one time, its species' entire population confined within one small habitat. Constrained by limited space and availability of food, it is a rather inactive creature with a slow metabolism, able to last for months without eating if need be, and reproducing slowly as well, producing only one well-developed offspring at a time which are immediately able to fend for themselves. Their large, dark-adapted eyes make them very sensitive and averse to bright daylight, and their small size makes them easy prey to the same winged creatures that make life in their underground biome possible, so instead they prefer to remain within the safety of their underground cavern homes, where food is readily available, enemies are absent, and this tiny, vulnerable creature enjoys a spot at the top of its local food chain as the unassuming, yet uncontested apex predator of its own little world.
While nowhere near as strange, or otherworldly and diverse as the Sub-Arcuterran Cavern System, Deeproost Cave is still a fascinating and unusual ecosystem in its own right, home to lifeforms shaped under similar and yet significantly different conditions that influenced their evolutionary path. Here, new organisms took shape that convergently adapted to survive in an inhospitable world half a planet away: becoming similar in some ways, and completely opposite in others.
The tropical rainforests of equatorial Gestaltia are easily one of the most biodiverse ecosystems of the Middle Temperocene harboring hundreds or thousands of different species. Here, in warm, humid regions with plenty of rainfall all year round and with no dry season, a wide array of plant and animal life, in many ways illustrating the progress of the seeded life on the planet, thrive in great abundance, the plant life nourished by the plentiful sun and rain, and the animals in turn nourished by the plants from the bottom of the food web up.
This equatorial biome, rich with life, itself plays a significant role in regulating the climate in the tropical regions of the planet, especially during the warmer climate of the Temperocene. Millions of individual plants, excreting moisture through transpiration, create a humid atmosphere that contributes to cloud formation and rainfall, and carbon dioxide sequestered by plant life reduces the carbon present in the atmosphere. In many ways, the rainforest itself acts as a buffer to more sudden changes in the climate, helping keep the local weather patterns stable.
Despite an abundance of trees, especially ones descended from stonefruit trees, due to the leaching from the heavy and constant rainfall, the soils of the rainforests are, paradoxically, very poor in nutrients: further exacerbated by local flora evolving to absorb as much nutrients as they can as quickly as possible before it washes away. On the forest floor, where light is poor and shaded by the forest canopy, smaller plants have adapted to thrive in low-light conditions. These include descendants of clovers, such as forest cloverferns (Polytrifolium spp.) and cloverbushes (Magnatrifolium spp.), growing close to ground level and having dark green leaves maximizing the amount of chlorophyll to increase their rate of light absorption and carbon fixation even in shaded environments. Others, herbaceous cabbage descendants such as the broadleaf brassica (Brassiplatus spp.) have wider leaves for greater surface area, and have a slower rate of growth than most other plants of the forest floor. With a large energy-storing root system, the broadleaf can go dormant when conditions turn unfavorable, only resuming activity when its environment is conducive to its growth once again. This strategy has even been adopted by some trees, such as the dwarf cherryberry (Diminutoprunus spp.), a species of stonefruit tree that has dwarfed itself to miniature proportions and adapted to poor-light conditions instead of competing with the bigger trees for resources, forming part of the understory of the rainforest at heights of only 4-6 feet tall at most.
Many trees of the competitive, resource-poor soils develop wide, criscrossing roots close to the surface as opposed to deep-boring taproots, in order to cover a larger surface area with which to collect water and nutrients from the surface of the soil. And many have help from some very unexpected assistants: symbiotic shroomors. Rootglobs (Theriotoma spp.) are one common example: neither plant nor fungus, they are in fact animals, or parts of them. Specifically, they descended from transmissible tumors of hamster ancestors that have become free-living, and their ability to invade and absorb nutrients from their hosts made them efficient decomposers and, eventually, tree symbionts. Rootglobs, growing on the buttress roots of trees, extend the tree's reach for water and nutrients with their web-shaped, slime mold-like growth, and are in turn nourished by the trees' sugars in their sap. As animal tissue, they can also synthesize proteins, nitrogen compounds and amino acids that they share with the trees, helping them contribute to their host's survival in a display of mutualism.
Not all shroomors are helpful to the trees, however. Woodtongues (Lingusarcophyton spp.), growing on the bark of many trees, are parasites, leeching off the trees' nutrients and feeding on rotting wood, eventually producing tongue-shaped growths that emerge from the wood, whose sporelike "founder cells" can wash off by rain and be carried to the roots of other trees. Fortunately, the abundance of the woodtongue has brought about another organism to keep it in check: woodtongue wasps (Linguluphilus spp.), whose females lay their eggs on the "tongues" as a nutritious food source for their larvae. The voracious grubs feast eagerly on the fruiting bodies, curbing their growth and preventing them from infecting too many healthy trees and overrunning their root systems.
The forest floor teems with many other invertebrates as well. Leaflice (Folisopoda spp.) and springhoppers (Caudisaltus spp.), descendants of woodlice and springtails originally introduced in the seeding phase as detritivores, now are just a few of a wide array of genera and species including scavengers, herbivores, fungivores, and even insectivorous predators among their ranks, filling the niches various small arthropods would in Earth's ecosystems. Less-efficient at retaining moisture than true insects, these plentiful "bugs" thrive in the damp, dimly-lit forest floor where they are safe from dessication, while true insects have sole dominion over drier biomes.
One true insect that does prefer the humidity, however, are the mush marchers (Migratermes mobilicasa). Unusually among termites, who prefer the darkness within tunnels underground and inside wood, the mush marchers travel along in lines in the open, shaded from heat and light on the forest floor and undergrowth. Foraging parties, flanked by big-headed soldiers, scour the leaf litter for edible material to chew up, proccess, and use to nourish their fungus gardens. Here, they again differ from other termites in an unconventional way: these gardens, knotted hollow masses of fungi and processed plant matter, double as mobile homes housing their reproductives, eggs and nymphs. This is advantageoous during seasonal floods, as they are able to move their homes to higher ground, a feat not possible with a fixed, permanent home.
All these abundant forest-floor invertebrates attract the attention of a remarkable little hunter unlike any the planet had seen until quite recently: the wooded squoad (Amphibiocochleoteuthis anuroides), a species of a group of skwoids that, in a first of their clade, have adapted to living on land, taking advantage of the vacant niche of small amphibians to thrive in a diverse array of a hundred or more species. Their harpoon-like radula, inherited from their marine skwoid ancestors, now possess a barbed tip for flicking out to catch small prey, and their six sucker-lined tentacles have become elastic springs, shortening and extending forcefully to launch the squoads forward in jumps that can be up to five times its body length. Despite their new terrestrial lifestyle, however, squoads are still dependent on moisture due to their aquatic eggs and permeable skins, making the damp forest floor of the rainforest an ideal habitat for them to thrive.
Above the forest floor, the understory of the rainforest is comprised of medium-height plants, adapting to survive with somewhat less light blocked by the canopy. Aside from dwarfed trees, other plants of this zone include feathery palmleaf (Plumobrassica spp.), another cabbage descendant but now specialized to have enormous, pen-shaped leaves to maximize the surface area for light absorption in their shaded environment.
High in the canopy, other plants partake of the race for sunlight and water by growing directly on the branches of the trees themselves. Known as epiphytes, these arboreal plants are commensal to the trees themselves, neither helping nor harming them, though if allowed to overgrow without being regularly fed upon by animals, they may end up smothering a tree. Among this are other clover descendants, such as jungle clovervines (Vinotrifolium spp.) whose long herbaceous stems clamber up tree trunks with the help of stolons that grow away from the root system to produce a secondary root system, each one acting as an anchor onto the trees' bark. Others are grasses, such as canopy firebloom (Arbopyrogramen spp.), which warns would-be consumers of its irritating chemical defenses with bright red-orange coloration, and arboreal leaferpool (Arbaquafolium spp.) which collect rainwater in their leaves and stems, which become ideal nurseries and micro-habitats for a host of different organisms. Some are even not plants at all, but lichens: a union of algae and fungus, such as beardmoss (Barbamuscus spp.), which hang down from the undersides of tree limbs and branches.
One unusual plant, the white ghostroot (Phantasmofolium spp.) has taken this relationship to the tree to a greater extreme. It now lives entirely inside the tree, its stems and branches snaking through the tree's tissues just underneath its bark, and sending deep-boring roots into the tree's xylem and phloem to siphon water and sugars from its host. However, it restricts its growth to avoid over-burdening the tree it depends on to survive: such to the point that if any of its stems and roots touch those of a separate ghostroot also attempting to grow on the same tree its roots will bore into its rival's tissues in an attempt to drain it dry and eliminate competition that threatens the survival of its host tree. The only time it ever emerges to the surface is to bloom, in which case a pale, white stem emerges from the bark and produces a cluster of small whitish-blue flowers, opening at night and releasing an enticing aroma just in time to attract its specialized pollinator, the ghostroot wasp (Phantasmophilus noctis).
By far, however, the majority of invertebrate life in the trees are ants: ever successful on their transported planet as they were back on their homeworld, they diversified into a vast assemblage of thousands upon thousands of species, many virtually identical to Earthly ants, but a few novel new standouts have emerged. In the Gestaltian rainforest, one such family of ants are the grubgun ants: unique among ant species in having a neotenic larval caste that never matures into an adult ant at all: instead remaining as an oversized larva whose silk secretions are utilized by other, matured ants as working tools for nest-building and defense. By giving up all other metabolic functions, these permanent larvae are able to quickly secrete large quantities of their silk, and are carried about by their metamorphosed sisters and wielded accordingly as they are needed. Goliath grubgun ants (Megalopaedomyrmex armadus), the largest of the grubgun species at about an inch in length, have two such castes of neotenous larvae: a smaller caste, carried by minor workers, that secretes silk for use in building nests out of leaves, twigs and dirt up in the treetops, and a larger caste, wielded by bigger major workers, that secrete large quantities of silk in long streams, acting as living glue guns that the majors use in battle to ensnare other invading ants. These opponents oftentimes include a smaller species of grubgun ant, the leaping grubgun ant (Saltopaedomyrmex minimus) which possess long hind legs for jumping long distances from branch to branch, while carrying a neotenous larva that secretes a "bungee cord" of silk as its carrier leaps across gaps. This way, they are able to quickly form silk bridges connecting nearby trees, allowing them to quickly send raiding parties to attack other ant colonies and plunder their resources.
Meanwhile, on the leaves of feathery palmleaf, a small, inconspicuous insect feeds upon the nutritious sap: the dairy oxgrub (Bovilarvinus spp.). Though they do not look the part, they are actually descended from lepidopterans: specifically, they belong to a clade known as the Hemimetamorpha or "half-changers", which develop piercing and sucking mouthparts but remain larval and wormlike even as adults. These sip large quantities of sap from leaves, but as sap is primarily sugar and water, they excrete most of these excess as concentrated, sugary honeydew: one that attracts the attention of a resourceful ant species, known as the yellow rancher ant (Agricumyrmex xanthus). These dutiful farmers protect the oxgrubs and herd them almost like livestock, tending to them, protecting them from predators, transporting them from one leaf to another to richer "pastures", and milking them of their sweet honeydew.
This idyllic lifestyle does not come uncontested, however: the rainforest understory is also home to the ranchers' greatest enemy: the white-headed reaper ant (Kleptomyrmex cephalbus). Measuring an inch long and with enormous, serrated mandibles, they are the bane of other ant species. They often prey upon leaping grubgun ants, seizing them in their tweezer-like mandibles and holding them up into the air to prevent them from freeing themselves with a powerful kick of their hind legs. But they are also the deadliest rival of the ranchers and their "cattle", raiding their herds like insect rustlers, making away not only with their oxgrubs but their larvae and pupae as well. The reaper ants kidnap the young of other ants and essentially enslave them, as their massive jaws, while terrifyingly efficient in warfare, leave them unable to chew their own food: and must be fed liquid regurgitated food by attendants of assimilated species with smaller and more manageable jaws.
To defend themselves and their herds, some rancher ants, some have struck up an unusual partnership with the masked lonestinger (Desperomyrmex spp.), a member of unusual solitary ants in which only winged queens and drones exist: never producing sterile workers and soldiers and living a self-sufficient life tending to their own larvae and providing them with food. At almost 1.5 inches long, with a hard exoskeleton, powerful mandibles and a venomous sting, a masked lonestinger is a force to be reckoned with, and can easily repel an advance scouting party of reaper ants before they can overwhelm the ranchers. In return for her protective services, the lonestinger is allowed to prey upon a few oxgrubs as food for herself and her larvae: a small price to pay for the ranchers as opposed to let the reapers wipe out their whole herd, and the rancher ants themselves too.
The aforementioned ant species are only a few of the most remarkable species of the rainforest, and are but a sampling among hundreds more of more-mundane types. This abundance of ants forms a significant part of the diet of an unusual tree-dweller: the magma treesquoad (Pyrocochleoteuthis arboreus). At home in the canopy, this squoad's six gripping tentacles are armed with suckers and are equipped with powerful longtitudinal muscles, allowing it to make long jumps from branch to branch, sticking tight upon contact with the first stem or leaf it touches. Its bright colors are a warning to predators: with a diet of ants, it is not only resistant to their toxins, but incorporates them into its skin secretions as well, causing an irritating burn to any predator that tries to put one in its mouth. While living in treetops, their eggs are still dependent on water, and so they carefully select pools of water in the leaves of arboreal leaferpools to act as their nurseries, with tiny, fully-formed squoadlets hatching from the eggs in a two to three weeks' time, already able to fend for themselves at birth. While young, they are well-camouflaged, as they build up their toxins by eating large numbers of ants, and only upon maturity do they display their bright colors, now fully-armed and an unpalatable experience for any amateur predator.
Meanwhile, the rainforest is irrigated by a vast network of rivers and streams, all of which harbor a varied collection of aquatic life. Aquatic plants grow in great quantities, some anchored in the bottom sediment and fully submerged, such as bottom gunkwort (Hydrolutugramen spp.), a type of freshwater seagrass, or growing along the edges of the riverbanks and peeking above the surface, such as reed bramboo (Calamugramen spp.). Descendants of clovers, their triple-lobed leaves still recognizable, float on the water's surface, some large and lily-like, others, such as clovefloaters (Aquatrifolium spp.) being small and duckweed-like, their long roots trailing freely in the water.
These plants provide food and shelter to various aquatic insects, which use them as refuges to hide from predators as well as ideal homes to rear their young. Reed waterwasps (Aquavespa spp.) clamber upon the stalks of reed bramboo, the adults feeding on the plants' sugary tissues but also using them as lookout points where they can dive into water and catch small aquatic prey to feed their carnivorous larvae. Specialized water-repellant hairs coat the waterwasps to trap air bubbles close to their bodies. Females use their wings as air tanks, allowing them to breathe as they dive: as such, they have become basically flightless, while males, who live only a few days and no longer eat, are fully flighted to search for mates.
Male waterwasps are not the only insects buzzing about slower streams and stagnant pools: an abundance of muckflies (Caenumuscus spp.), small dipteran flies, form whirling clouds above the surface feeding on pond scum and algae, while their aquatic larvae swim beneath in jerky wiggles, filtering out particulate detritus from the water. Less benign, however is the much more fearsome cousin the masaka, with one local species, the red-legged masaka (Culicimimus erythropus) being the largest of its clade, boasting a wingspan of nearly 3 inches. While both sexes feed on sap and nectar for sugar, females, in convergence to numerous other Earth dipterans, have developed a taste for vertebrate blood: piercing their skin with needle-like proboscis to puncture small capillaries and acquire a protein-rich meal. In spite of this gruesome adaptation, however, the masaka provides a vital role to the ecology of the riverside habitat, as, by feeding on larger animals, they return nutrients and biomass from higher rungs of the food web back to the lower trophic levels of the insect scale and beneath. The larvae of maska and muckflies, teeming by the millions in any available body of water, are a vital food source for the shrish and pescopods and aquatic insects of the ponds, lakes and streams, which in turn are themselves eaten by larger animals. In essencce, the masaka's bloodthirsty habits actually make the entire micro-ecosystem possible, as they exploit a food source much bigger than themselves to rapidly swell their numbers. Their larvae are also joined in the water by pond scuds (Allocrustaceus spp.), small crustaceans that, perhaps surprisingly, are not shrish at all, but descended from small freshwater crustaceans introduced accidentally into the biome during the early founding years as dormant eggs, though the immense success of krill-descendants has stopped them from making a large impact and thus remained similar to their small, ancestral forms.
Adult masaka and muckflies are prey to draclets, here represented by the turquoise pond draclet (Vespadraculus caeruleus), long-bodied, stingless wasps that have adapted to hunt other flying insects midair, utilizing unparalleled agility and maneouverability to capture the most evasive of prey. Seizing them with their grabbing, hooked legs, they dispatch their prey with their mandibles instead, either to eat for themselves, or haul back to their nests for their larvae. Each mother draclet can simultaneously tend to up to a dozen different larvae at once, housed in small cuplike nests hidden near water and made of mud and debris: and containing only one larva each, as the young are cannibalistic and would eat one another if kept together in the same nest.
These aquatic insects are in turn a source of food for the many species of shrish and pescopods that inhabit these rivers and ponds. A numerous collection of these mollusks and crustaceans, filling the empty gaps of Earthly freshwater fish, forming a middle rung of the river ecosystem's food chain. Some shrish, like silver shrinnows (Sylvopescocaris spp.) are found almost anywhere, gathering wherever algae and detritus are abundant in more gentle currents, while red-lined brookshrawns (Erythrolineocaris vulgaris) shoal in faster-flowing streams and rivers, braving the upstream currents to spawn. On the silt-covered bottom, flat-shelled mudtrawlers (Platylutucaris sublacuna) rummage for the remains of other shrish's food scraps, droppings and carcasses, helping keep the water clean and preventing it from becoming too cloudy due to a build-up of decomposing waste, which can lead to microbial blooms that can suffocate all the ponds' residents.
Among the pescopods of the rainforest river system, none are as bizarre as the spotted flopsider (Laterocochleus asymmetroculus), a surface-dwelling species that prefers slower-moving currents where insect larvae aggregate. Its most noticeable features are its sideways-swimming posture, and the fact that its eyes are completely asymmetrical: one eye, small and long-stalked, is adapted for seeing above the water's surface, while its other eye, shorter-stalked and larger, is better equipped for underwater vision, with the two eyes differing in the thickness of their lenses to account for the difference of refraction in air versus in water. This asymmetry can happen on either side, linked to the same mechanisms that determine whether other gastropods have their shells coil to the left or to the right, in spite of the flopsider's ancestors having lost their shells a long time ago as they adapted to a more active lifestyle. Able to see both above and below the surface, the flopsider can keep watch for predators both under the water and above the surface.
And it has cause to be wary, as it, and many other small aquatic animals, are prey to the banded cuttercuttle (Venatocochleoteuthis tigris), a freshwater skwoid that is the largest invertebrate predator of the jungle rivers. Measuring up to a foot in length, this powerful hunter is equipped with a saw-like radula to help dismember its prey, as well as small hooks on the suckers of its tentacles that allow it to grip its quarry. While its prey typically consists of shrish and pescopods, it is not picky as an opportunistic hunter, and small pondrats, wading pterodents, and even smaller members of its own species are likewise on the menu.
And of course, while millions upon millions of plants, fungi, microbes and invertebrates form the bases of the rainforest ecosystem, the numerous vertebrate hamster descendants live and flourish in this biome in many shapes and sizes. Dominating as local megafauna, these Gestaltian forms are distict from the fauna of other continents, evolving in geographic separation yet converging in many ways to the other, unrelated animals to whom their niches share.
Notable among them are one of Gestaltia's unique animals, the trunked walkabies. Generalist omnivores, these are represented in the rainforest by large, ground-dwelling omnivores such as the spotted forest trunkuffle (Dipodotapimus punctalbus), a forest-floor forager that feeds on fallen fruit, seeds, roots, fungi, shroomors and invertebrates, while up in the trees arboreal rhinocheirids such as bracelet-nosed treebumms (Nasobrachius annulocheirus) feed on leaves, flowers, fruit, and insects as they climb and leap across the branches on their six prehensile limbs, in many ways being the Gestaltian equivalent to Mesoterra and Arcuterra's lemunkies, absent on this continent, though their cousins the basal squizzels, such as the blacktip squizzel, (Melanocaudosciurumys minimus) are also native here as a few odd species, hoarding the seeds and fruit of epiphytes and helping contribute to their spread.
Meanwhile, ringtailed checkerbacks (Arbosaltocricetus annulus) also occupy the canopy, browsing on the abundant epiphytes that grow on the branches, resistant to their defenses that would make them unpalatable to squizzels and treebumms. They descend from the few remaining hopping boingos, who, displaced from the plains by podotheres called rebounders, have now taken to the trees in a last-ditch effort to survive the changes of the Middle Temperocene, their resistance to toxic bleedweed grass proving useful in occupying the barely-contested niche of epiphyte browser.
Another Gestaltian endemic, the badgebears, are also found in the rainforest, occupying an unusual dichotomy of niches. Some, such as the brown bruinbrowser (Phytoursomys macronyx) are almost entirely herbivorous, foraging on a diet of fruits, plant matter and occasionally invertebrates, others, descendants of the predatory fasbears such as the jungle bearguar (Pantherursomys pardus) are obligate carnivores, and occupy the top spot of apex predator, their diet including walkabies, herbivorous badgebears, and, most significantly, the various species of ungulopes, such as low-browsing pale-rumped junglebucks (Sylvocervimys alboposterius) that eat low understory vegetation and high-browsing rainforest altolopes (Sylvaltungulus conoceros) that browse on leaves of higher canopy trees but also relish the abundant clovervines and beardmoss growing on the tree branches.
One animal even the fiercest bearguars will not touch, however, is the orange-tailed thorntop (Echinospinomys xanthus) a large member of the heckhogs related to the irididescent bluehog, whose sharp quills double both as decorative structures to display to other members of their own kind, and defensive weapons that protect them from predators. Thorntops, while primarily herbivorous, will sometimes catch and eat poisonous squoads, then lick the irritating mixture onto its quills as an additional line of defense. While they are resistant to its compounds, other animals are not, and being pricked by their toxin-laced quills can lead to painful inflammation that can last for days at a time.
Above in the trees, a wide diversity of ratbats call the branches and trees home, their nests secluded in tree hollows where they rear their young until they learn to fly by themselves. While white-streaked barkpickers (Phyllonyctomys melanoleuca) gnaw on the bark of trees to search for insect larvae in the wood, ebony shaderwings (Umbrapteryx corvinyctus) gather berries and seeds that they stash away in larders they chew into trees, and flocks of tricolor aerimuses (Varicolonyctus vulgaris) swoop and dive as they catch flying insects midair. At night, once most of the diurnal ratbats have gone to roost, nocturnal ones, the more basal evening dingbats (Noctopteromys macrotis), take to the air to hunt for night-pollinators like moths. They are distinctive in that their sprawled limbs make them clumsier on the ground than more derived ratbats, and thus prefer to hang from branches to rest, and avoid competition from their diurnal kin by foraging in the cover of darkness: relying on echolocation rather than sight to avoid obstacles and home in on prey.
The rivers and streams of the rainforest, with plentiful food, are frequented by many other hamster species too, which have adapted to a semi-aquatic lifestyle to take advantage of its resources. Forest creek pondrats (Riverrocricetus sylvus) build their nests of sticks and twigs on riverbanks, plastered with mud to conceal it from predators. They are herbivorous, and greatly relish reed-like bramboo that grow on the water's edge, in particular the tender young shoots that spring up feom the main rhizome. Meanwhile, wading pterodents, such as the black-legged swanji (Cygnornimys nigripus), a relative of the mountain-dwelling silver soarers, lives a lifestyle in great contrast to its alpine cousin, foraging in ankle-deep water for the shrish, pescopods and skwoids that make up much of its overall diet. This is in spite of most pterodents being cumbersome at taking off from the ground, but the abundance of trees enable it to make a quick getaway with the help of its wing claws that enable it to quickly scale trees for an easy launch into flight, should any attacker be persistent enough to pursue it up the trees.
With a warm, tropical climate all-year round, the Gestaltian rainforest is unsurprisingly welcoming to ectothermic rattiles, of which many unique kinds are found here too. Scurrying across the leaf litter are red-banded candytails (Saccharosauromys erythrocauda), whose colorful tails act as signals for display, and distractions for predators to draw attention away from their heads and bodies. Uniquely, while they are unable to regrow any lost portion per se, the stub will lengthen its remaining vertebrae to a length similar to that of the original tail but stiffer and with fewer joints, and in some old specimens which had lost their tail several times their now comically-rigid tail can be comprised entirely of just one or two grossly-lengthened bones.
Up in the canopy, the abundance of hundreds of species of ants has unsurprisingly drawn the attention of arboreal burrowurms, such as purple-tongued piedvipers (Erythrophiomys phagomyrmex), which use their short foreclaws and long tongues to break into the nests of ants and gorge themselves on the residents. Their thick keratinous scales are extremely resistant to bites and stings, and their acidic spray has little effect thanks to a transparent third eyelid that protects their eyes when they feed. In fact, piedvipers are able to sequester these compounds to deliver painful stings themselves through the glands on their front claws that they use for self defense. So effective is their weaponry that many other burrowurm species, collectively known as "false piedvipers", mimic their coloration despite not possessing any claw-stings of their own.
And with such an abundance of flora and small invertbrates, the flying wingles are also present, most commonly the goldwing wingle (Aureosauromys splendipteryx) which flits and flutters among the plentiful blooms gorging on nectar, pollen and small insects. At night, they take shelter among the nooks and crannies of tree branches and their own small forests of epiphytes, females and immature males more drab and brown to hide among the mossy bark while mature males sport brilliant yellow tones that make them stand out: perhaps even as a deliberate handicap that any male which can survive in spite of, is a truly fit male and a worthy mate indeed.
Together, all these plants and animals, and the various organisms in-between, form the complex and diverse ecosystem of the Gestaltian rainforest. Thriving in millions of species, be they up in the trees, on the ground, amidst the leaf litter and soil or swimming and wading in the web of rivers spreading across the forest, from small insects to large megafauna, all these living things are inextricably linked to one another, and a testament to the adaptability, codependence and diversity of life on HP-02017 as a whole in the era of the Middle Temperocene.
Surrounding the Middle Temperocene continent of South Ecatoria, the small, pelagic islands off its coasts have become the hotspots of unusual and remarkable evolutionary forms. Here species arrived either from being cut off from the mainland, rafting on debris in storms, or travelling there upon their own accord: and in isolation they have been morphed by time and natural selection into unique species found nowhere else on the planet.
Reef Ridge Isle, to the continent's northeast, is as its name implies: a sandy landmass north of the North Bridge Reef with parts of old dead coral exoskeletons that extend above the surface to form a landmass that, in some areas, piled up with white sand--the eroded remains of old coral chewed, processed and excreted by a wide array of coral eaters over countless millions of years-- and other sediments, upon which plants have taken root, delivered by the droppings of ratbats and pterodents.
These plants are fed upon by one rather unlikely and unexpected grazer: the insular giant landshrab (Megalocarcinocaris giganteus). Largest of the terrestrial shrish, this slow-moving, primarily-herbivorous species lives entirely on land as an adult, with other members of its genus widespread well across the mainland and the surrounding islands thanks to the manner in which they reproduce. While land-dwellers as adults, they return to water to breed, releasing thousands of planktonic young that drift into the sea far and wide, eventually seeking out islands and shores as they mature and moving onto land once molted into miniature adults. The insular giant landshrab, however, has become a distinct species, as it prefers to spawn in tide pools, where its young are well-protected. They bear smaller clutches, but larger and more-developed young, which, with their secluded upbringing, have become reproductively isolated from the other seafaring species of landshrabs.
The beaches and shores of this island, in the meantime, have become the rookeries of another unique endemic species, the ridgeland gnawrus (Macrootariimys dimorphis), an omnivorous bayver that gathers here in great numbers to rest, breed, and birth their pups. Most distinctively, males can grow up to thrice as large as females, and sport powerful incisors and canine-like first molars: useful for both feeding on a wide array of food like shrish, shrabs, bivalves and even marine plants on occasion, and also for fighting rival males to score breeding rights to harems of receptive females. This aggressive dominance-based hierarchy is the reason behind their marked dimorphism, as the larger males held an advantage when it came to battling for mates and territory, pushing smaller, weaker males to the fringes of the colony where they are both more exposed to predation by phorcas and have lesser reproductive success: factors that heavily skew the sex ratio of the adult gnawrus population toward fewer males and more numerous females.
Smaller species live on the island as well. In the absence of typical "basic rodents" such as furbils and duskmice, a small, flight-inhibited ratbat, the ridge rockbat (Micropteronyctus coralinsulus), fills their niche instead, scurrying about on the ground to feed on seeds, roots, tender shoots and small invertebrates, being a poor and infrequent flier that spends most of its time on the ground seeking cover underneath dense vegetation. A small rattile lives here too: the reef ridge rafter (Insulosauromys coralis), which roams the coasts of the island during dusk and dawn, feeding on insects and other small arthropods. Able to float on water thanks to microscopic hairs on its underside that make it nearly completely waterproof, holdovers from its ancestors that lived in the rainy, flood-prone jungles of South Ecatoria, a lucky few survived being washed out to sea and made it to the island by floating there, either on their own accord or hitching a ride on driftwood or beachpeach fruit, a small percent arriving just in time before they succumbed to dehydration or predation.
But rafting is not the only way for a rattile to settle onto a secluded island where they can evolve in isolation. On the Strait Isle, east of South Ecatoria, some have done so in a perhaps unexpected manner: they flew there.
On the forest floors of the island, the thorny quilldrake (Echinopteromys stridulus) roams the leaf litter, searching for the abundant small invertebrates that it eats. It would otherwise be a typical rattile at first glance, save for four spiny appendages on its back that in males, are rubbed together to produce high-pitched noises: a feature that betrays its ancestry as a flightless wingle that had emerged independently from the nephtiles of Isla de Oof.
Unlike the nephtiles, however, the flightless wingles of Strait Isle have remained small and inconspicuous, and no longer produce a flighted juvenile stage. Their wings, modified hair attached to muscular knobs, have been reduced to small keratinous spikes, as is the case with the ground spurwing (Apterasauromys rotundus), a burrowing herbivore that uses its moveable spikes as defensive structures when the solitary creatures tussle against their own species over territory and food.
The forest floor, in the meantime, is teeming with more unusual creatures: golden miteshrabs (Aurocarcinocaris minimus), tiny land shrabs that time their breeding cycles to the high tides as they, like the giant landshrabs of Reef Ridge, are terrestrial crustaceans that still return to sea to breed. They swarm along the ground by the thousands, even millions, carpeting the forest floors and beaches in a bright yellow mass of moving bodies migrating oceanward. Such conspicuous gatherings draw the attention of many predators, such as quilldrakes as well as seagoing ratbats and shore-living skwoids, but, numbering in such quantities, the proportion consumed by predators scarcely even dents their teeming numbers.
The isle's most remarkable and intriguing inhabitant, however, is perhaps the muddy fudgeback (Amphibiocheloimys pterapus), a member of a group of marine shingles known as the sterapins. Uniquely among its clade, which are fully-aquatic as they give birth to live young, the fudgeback retains the ability to haul itself ashore and bask in the warm suns' rays, its dark coloration helping it raise its temperature quicker at such a cool southern latitude. Feeding on mockjellies and sea plants as adults, the young are conversely carnivorous to fuel their rapid growth, and their ability to clamber onto land enables the juveniles to pursue and feast upon the abundance of golden miteshrabs whenever they migrate to the seashore.
North of the mainland is the Peachland Isle: a small landmass once connected to the mainland that broke off at least a few million years ago. As such, most of its species, as recent divergences, still resemble the species of the northern beachpeach forests, yet are still recognizable as their own distinct species.
The entire landmass is basically covered in beachpeach forest, and thus its residents are ones specialized for a mix of the aquatic and arboreal. Present here are the sunkeys, specifically the yellow sunkey (Xanthaquapithecomys insularis), living in social groups that forage in the water for aquatic plants, beachpeach fruit and marine invertebrates, and retreat into the canopy of the overhanging branches to seek safety from occasional transient predators such as bayvers and cricetaceans that sometimes visit the flooded forests. Similarly adapted is the peachland tree rodder (Arbolutromys leptopus), which can climb up the trunks of the beachpeach to rest safely for the evening. They coexist quite amicably with the sunkeys due to them being specialized eaters of quillnobs and other marine gastropods and thus competing very little over food, though during the breeding season when the sunkeys become more territorial the tree rodders are often bullied away by their otherwise usually placid neighbors, and thus wisely learn to keep their distance during this time.
Meanwhile, inching along the branches of the canopy trees is the green beachpeach piedviper (Arbophiosauromys viridans), a burrowurm that much like the sunkeys and tree rodders lives a double life as both tree-climber and semi-aquatic swimmer, equipped with both hooked limbs and tail for clinging onto branches, and a long, flexible body that can undulate smoothly to propel it through the water. Most piedvipers are insectivores, and in this case it plays a similar niche in a very different ecosystem: its diet consists of peachroot mermites (Myrmecocaris spp.). These colonial shrish live among the root systems of the beachpeach trees, and even excavate tunnels in the wood with their claws to build shelters in the roots where their egg-laying queens can reside. The green beachpeach piedviper, while resting amidst the treetops most of the time, descends into the water to feed on the mermites, providing an important service in keeping the mermites under control lest they damage the roots too much and harm, weaken or even kill the host tree.
And furthest east to the mainland is the peculiar Isla Pterodens: an atoll composed of a circular volcanic landmass surrounding a shallow central lagoon. This lagoon is teeming with life where photosynthetic algae grow in abundance and small shrish and pescopods gather in large shoals to seek refuge from deeper-water predators: eventually bringing about one of the most remarkable phenomena of evolution illustrating both its resilience and also its limitations.
Titan prunejaws (Titanopteromys thanotherium), notable for their wrinkled, ridged and brightly-colored lower wattle found on the males as a sexual display, are one of the heaviest of the flying pterodents, and range around the southern coasts of the mainland, primarily feeding on small aquatic prey but also being drawn to beached carrion of dead marine animals, being opportunistic scavengers as well when such a calorie-rich meal presents itself. Due to their weight and laborious takeoff, flight is an energy-intensive effort that remained due to its payoff in allowing the prunejaw to find food and escape danger: which makes it perhaps rather unsurprising that, upon settling onto Isla Pterodens, the prunejaws very quickly abandoned flight in just a few generations when presented with a productive land, with no terrestrial enemies, where they could simply wade through the lagoon and easily forage in the abundance, becoming the insular subspecies known as the inevitable prunejaw (T. thanotherium invictus).
And inevitable indeed they seem, for, prior to their current colonization in the last few hundred thousand years, the atoll of Isla Pterodens had completely sunk beneath the waves during warmer periods of decreased glaciation and elevated sea levels. Their idyllic paradise now an inescapable death trap, the now-flightless prunejaws were unable to escape the demise of their home, and quickly became extinct...at least, for the time being.
In the fluctuating sea levels of the Temperocene, as the polar ice caps expand and recede, the atoll had since submerged, and subsequently, re-emerged, at least several times in relatively recent history, within the span of a couple million years. And each time, as its productive shallow lagoons became ever so suitable, nearly tempting, to the prunejaws, they repeatedly came to settle here, became flightless to conserve energy and resources, and invariably perished when the landmass disappeared into the sea. Evolution, devoid of a goal, had cyclically doomed a small population to repeated extinction in its haste to remove an ability no longer currently useful, without the foresight of it becoming advantageous in a later ecological change. And yet, in seeming display of what could almost be called stubborness, the same species landed upon the same atoll and became the same thing that had lived and died there not too long ago: perhaps again and again for as long that the island's empty niche, and the species built to fill it, continue to exist across the span of deep time. The inevitable prunejaw is but the latest iteration in a series of evolutionary experiments that serve as examples to highlight the absence of any direction to evolution's random progression-- save for whoever or whatever is just 'good enough' to survive in the moment.
While a relatively secluded ecosystem, the caverns of Arcuterra have expanded greatly over the last few million years. Consisting of a network of tunnels, chambers and crevices spanning for miles underground, the floor space of the caves have now exceeded those of a small island comparable to Earth's Tasmania-- and has gotten large enough to have several sub-biomes within itself, some levels more superficial and closer to the outside world where the abundance of nutrients trickling in allows the lush forest-like growth of subterranean pseudo-flora, and others beneath the upper layers where groundwater and detritus accumulates, forming stagnant, muddy swamps where, against all odds, life finds a way to thrive.
One of the ecosystem's most abundant animals are the feelerflits: the caverns' only flying animals. Descended from dipteran flies, their forebearers once did lose their wings in their initial colonization--yet over time re-evolved this ability through atavistic mutations once the caves had expanded enough to make flight advantageous again: though now, in pitch black darkness and without vision.
Feelerflits, however, managed to adapt by developing especially-hypertrophied feelers both on their antennae and their abdominal cerci, giving them the ability to detect movement both forward and behind. This, coupled by pressure sensors and long hairs on their feelers, allow them to discern their environment in flight, while olfactory and theroreceptor cells allow them to pick up thermal and chemical signals to recognize food, enemies, and conspecifics.
Most of the common feelerflits (Phantasmusca spp.) are generalist omnivores, feeding on decaying matter, shroomor spores and fungi, but some, in the abundance of resources and lack of competition, have ascended a rung in the food chain. The murksquitoes (Anophelomimus spp.) have become part-time parasites, supplementing their diet of mocklichen spores by biting larger animals such as daggoths, especially females that require additional protein in producing their eggs. Others, the darkdarters (Quadropteroides spp.) have become predators, preying on other feelerflits. With their halteres enlarged to resemble a second pair of wings but used as organs of balance instead, they are agile in the air, seizing other, smaller feelerflit species with spiny grasping forelimbs and using a sharp proboscis to pierce the bodies of their prey.
This abundance of insects, arthropods and other invertebrates has led to other unique specializations among the daggoths: the cavern systems' dominant troglofauna. Many are specialized insectivores, typically smaller species, but also some unusual outliers among the larger kinds.
One such creature is the trunked tendrilcrown (Oroproboscimys nasocephalus), a member of the cavehopper family that, unlike its other grazing kin, has adapted an elongated snout from the elongation of its lips, forming a trunk-like appendage with its mouth opening at the end, out of which emerges a long, sticky tongue equipped with small barbs, ideal for piercing through mocklichens to get at the interior, reaching into crevices to pull out rootlike mycelia, and most importantly to raid insect nests and feed on the inhabitants. Its trunklike appendage only contains its mouth, with its nostrils set far back behind the top of its head, keeping the vulnerable orfices far from reach of its biting insect prey.
Tendrilcrowns, like most other cavehoppers, are gregarious creatures that seek safety in numbers from predators like blindmutts and tendriltooths. They use their tail, atypically long for a daggoth, as a scent-marking organ to set territorial boundaries and identify related individuals. Yet, as their social behavior are merely for protection, their individual bonds are rather weak. When startled by predators, they individually flee with powerful thrusts of their leaping hind limbs, displaying little concern for their fellows whose company they only partake in to reduce the chances of individually being caught.
The cavehoppers may be agile and flighty creatures, but in the limited space, not all daggoths share their energetic means of movement. Some daggoths are content with a slower-paced life: especially those that live in the lower levels of the cave systems where fewer food is available and energy is better off conserved.
The gloomy squonk (Trogloporcimys nasoculus), one species of the gloomhogs in relation to the biblarodons, lives in the basement-levels of the cavern systems: where the muddy deposits gather into the large, wide chambers into a sort of underground marshland. Here, underneath the organic sludge, specialized filamentuous fungi grow in soggy, fibrous clusters, absorbing and converting the detritus back into biomass that, in turn, is the primary food of the gloomy squonk. Its ghostly eye-like orfices are in fact enlarged nostrils on its inverted, upturned snout, as it has adapted for spending much of its time wallowing in the subterranean swamps scraping off the fungi from the bottom, surfacing time and time to breathe. With larger nostrils as well as a markedly larger lung capacity, it is able to take in more air per breath, allowing it to make the most of the thin, oxygen-poor atmosphere so deep beneath the ground.
Its sluggish demeanor, large fat-storing body and glycogen-storing liver allow the gloomy squonk to survive for long periods without food, in one of the less-hospitable regions of the cavern system, where growths of its preferred forage follow irregular boom-and-bust cycles depending on how much nutrition is available from higher rungs. This, however, makes it an ideal potential meal for younger tendriltooths that may wander down lower crevices to avoid competition from aggressive and cannibalistic adults. However, while slow and typically placid, the squonk is not entirely defenseless. Its jaws, strong enough to tear fungal mycelia from rocky anchors, can also inflict a vice grip onto a would-be predator, after which it submerges into the muddy sludge in an attempt to drown its assailant.
Similarly, while some of the blindmutts became active, pouncing ambush predators, others, the cavegleaners, took on a more slow-paced lifestyle, wandering along as foragers and scavengers, picking on shroomors, insects, small daggoths and carrion, and thus alleviating competitive pressure from the tendriltooths, who now seldom consider them a threat and rarely bother attacking them.
The ridge-headed whiskersaw (Heliconasodon rubrilophus) is one such cavegleaner, often drawn to the leftover kills of tendriltooths to finish off the remains left behind once the predator is sated. Like the tendriltooth, the whiskersaw is equipped with sharp keratinous serrations on its nasal tendrils that function much like teeth. Yet now, with its foraging lifestyle, the whiskersaw now puts its false dentition to a strange use: coiling its two most prominent tendrils into tight spirals with the spines pointing outward, it then rotates them against one another as they uncoil back and forth: forming two abrading "polishers" that cleanly scrape the last residues of meat attached to bones, especially those out of reach of other predators. When uncoiled, these spiny appendages can also be inserted into hollows of bones to access the marrow, or be probed into the burrows of small prey to be extracted from their hiding spots.
The other conspicuous feature of the whiskersaw is of course the two fleshy ridges that adorn its head: the frontmost rims of which are made of highly-vascularized tissue that can be engorged and distended with specialized blood vessels to release a small amount of body heat. These are picked up by the thermoreceptors found on the nasal tendrils of other whiskersaws, in essence being used as a display organ by a species without eyes to see visual cues. Being mesothermic, like most daggoths, the display is a very energy-intensive effort in relative terms, and to the solitary creatures only means one of two things: a dominant male asserting his strength to a potential rival, or a receptive female advertising her readiness to breed. Also like the majority of other daggoths, the undeveloped but precocial young recieve minimal parental care, nursing for only a day or two before being deposited near abundant food sources conducive to their growth and survival.
A wide variety of large fauna now thrive among the drier regions of the caverns, which, while still smaller than surface animals due to the more limited space and resources, nonetheless reach impressive sizes for a cave-dweller. But the aquatic biomes of the caverns are not left out by such trends, as some aquatic daggoths have grown quite large, in particular the deeplake trogadile (Troglomyosuchus pennadactylus) which can reach lengths of up to a meter long or more.
While the tendriltooths are the top predators of the land, the trogadiles are the apex carnivores of the underground rivers and lakes where an impressive array of organisms thrive: aquatic insects, shrish, pescopods, hampreys and tubesnouts alike, dependent on a base producer of chemosynthetic bacterial mats and aquatic meatmoss, growing in thorny fronds like animal kelp. All of these are food for the trogadile: not a picky eater, it catches food with its muscular fused nasal lobes as well as two smaller tendrils equipped with sharp claw-like points, and using its extensible snorkel-like nostrils to breathe at the surface every few minutes, sometimes lying motionless just below the surface with only its snorkels exposed, waiting to strike at unwary prey.
Their specialized limbs, modified into flipper-like paddles, undulate rhythmically to propel themselves through the water, but, conversely, now make them practically immobile on land as grown adults, entirely helpless and vulnerable if beached. Young individuals, a few inches long at birth, however can manage a clumsy scuttle across dry land, enough to be able to disperse into other bodies of water. Once grown, they are permanently waterbound, though populations can still intermingle genetically despite isolated pools being separated, due to the amphibious capabilities of the juveniles.
Many branches of the daggoth evolutionary family have thus produced a wide variety of some of the strangest and most alien-looking forms ever assumed by a rodent: to such an extent that many are scarcely ever recognizable as such. Many of these arise from derived lineages, but, from the gothtles, one of the most basal lineages, bizarre yet oddly familiar forms too have since emerged. These animals, in their basal forms once top predator of the caves, now find themselves at the bottom of the food chain, preyed upon by their distant kin: while some such as the xenomures adapted to flee and hide, others armed themselves with strange weaponry to to ward off and injure their enemies.
The veiled sixclaw (Hexaceratonychus cryptocephalus) is one such unusual species that, when threatened, conceals its face and sensitive nasal tendrils in a fold of thick skin as it curls itself up into a tight ball: leaving only six prominent defensive spines exposed. These long, horn-like projections are, surprisingly, actually elongated claws: attached to mobile, specialized digits, they can point in any direction to painfully stick into a predator's mouth, and, even when moving about and actively foraging, the sixclaw bears its weaponry in arms, raised above and behind its body to make it difficult to grab. Able to move together, they can pinch the tendrils and toes of an enemy, hard enough to draw blood, even if successfully picked up.
This ability for the digits to grip in junction has been put to good use by some species. The shield-faced pintler (Durocephalomus carcinychus) specifically has hypertrophied the first two pairs of its digits to use almost as grasping pincers, able to partly oppose and each equipped with a large, retractable claw. These serve it good use in excavating burrows, tearing apart food, defending itself and, most remarkably, used in intraspecific combat. Males can be up to twice as big as a female, and sport greatly enlarged claws and a larger keratinous facial shield that, while used in the females merely to protect their faces while burrowing, are defenses for males when they fight over territory, mates and resources, lifting each other up and tossing each other away as they tussle for dominance, with the losing combatant occasionally losing a few digits in the process.
These defenses, armor and burrowing abilities all reach their peak in the armored crustster (Carcinocricetus memeticus), a smaller and more placid relative of the pintlers that has evolved a more compact body and a single enlarged shield covering most of its back that, with its sharp-spined edges and smooth curved shape, makes it resistant to all but the most specialized of predators. Its powerful front claws are primarily used for digging, while its back, reinforced by a thick and sturdy spine with multiple interlocking vertebral processes, allow it great strength for its size, able to use it for leverage to wedge itself under large stones or into crevices, both to make itself inaccessible to enemies trying to fish it out of its hiding spots, as well as access small invertebrate prey taking shelter underneath.
From a single founding species descended from the stellasnoots that found a suitable home in the secluded caverns of Arcuterra, the daggoths, a clade of subterranean molrocks of distant relation to the rattiles, have since diversified over the last 25 million years in isolation. As the cave systems naturally expanded over the course of many millennia, the ecosystem too grew bigger, as it created more room for a wider and more diverse range of species to thrive.
Over millions of years, the upper chambers of the cave system became more open to the surface, resulting to not only a slight but significant influx of oxygen into the ecosystem but also nutrients from the surface, such as organic detritus and the abundant droppings of transient species such as roosting ratbats that nest in the surface chambers, washed down into the caves by rain. These fuel the abundant growth of bacteria, mocklichens and meatmoss, the cavern ecosystem's producers in the absence of plants and sunlight. With an abundance of food, space and, relatively speaking, oxygen, the life of the caves have since grown more diverse and complex than ever before.
Many of the daggoths have remained unchanged from the first forms that were the earliest colonists of the caves. The gothtles, small, mouse-sized insectivores, continue to stick to the ancestral lifestyle, as small, slow-moving ambush hunters that relied on stealth to pounce on insects. Yet the ancestral niche now comes with one drastic difference: they are no longer the apex predators of their environment. Abundant and fast-breeding, the gothtles are now the lower rung of the food chain as larger predators have since evolved from other branches of their kin.
While slower basal gothtles now rely on camouflage by scent and touch to evade enemies, numerous lineages have since evolved speed and evasiveness in order to outpace their predators. One such group are the xenomures, such as the four-plumed xenomure (Xenomuris tetradactylopluma), with long, slender legs that allow them to scurry quickly across the fungal and meatmoss mats to escape their enemies and hide among the maze-like growths to lose their enemies' trail. Two pairs of modified digits act as antennae fore and aft, giving the xenomures a vivid perception of obstacles in their surroundings while moving quickly in the pitch black darkness. These timid omnivores, in many ways, have come to be the caves' ecological parallel to "typical" rodents like furbils and duskmice on the surface, with some even harvesting and storing fruiting pods of mocklichens in burrow larders to eat later, and thus helping the mocklichens proliferate to new areas.
Other lineages of the small gothtles have also evolved more active lifestyles as dynamics of the ecosystem have changed. Some, such as the long-bodied common skitter (Longicorpomys polypus) developed slender bodies and shorter limbs to specialize in hiding in small crevices in the rock walls, well-protected from predators, where they can feed on the fungal mycelia, the buried "roots" hidden underneath the organic soil-like detritus mats covering the cave floors. Others have become small hunters of their own right, paralleling the chrews and scabbers of the surface, like the earthumb arthoid (Dactylotomys auricheirus), equipped with two front digits bearing pointed claws positioned next to its head almost like ears, that it uses to root out small prey, such as insects, nematodes and wormlike maggoths out of their burrows and out from growths of mocklichens and meatmoss.
Virtually every surface of the cavern system has offered a habitat for life, including the walls and the ceiling of the caves, with the walls and roofs forming elevated "branches" and dangling "vines" of various vegetative plant-analogues, which are fed upon by "browsers" adapted to reach high up on to access fungal growths inaccessible to other ground-dwellers.
The ceilings, in particular, are abuzz with a surprising diversity of organisms dwelling amidst the overhanging stalactites. In particular, the dangling "vines", in reality complex filamentous fungal hyphae nourished by a symbiotic relationship with chemosynthetic bacteria, produce buds that exude an odorous scent, that draws in the feelerflits: flying insects descended from dipteran flies that, with long and very sensitive antennae equipped with tactile, thermal and olfactory receptors, have secondarily regained their power of flight and are able to navigate even without sight and home in on the buds that produce nutritious carbohydrate-rich liquids in return for it spreading its spores.
One descendant of the roof stalac has since adapted to exploit this relationship. The bulbous-snouted budwight (Nasofungiosus imitator) has developed specialized bud-like growths at the end of its nasal tendrils, that sport modified sebaceous glands that excrete a scent similar to those of the vine blooms, the chemicals of which it acquires and secretes by eating the blooms themselves. Then, lying in wait, anchored onto the surface of stalactites or perched amidst the vines, it waves its tendrils in the air in anticipation of an unwary feelerflit blundering into its trap, to be ensnared by seven long and flexible tendrils and passed into the mouth to be eaten.
Curiously, despite its purpose of mimicry, the budwight's tendrils in fact look nothing at all like the vine buds, being simple enlarged growths at the ends of the knobbly nasal appendages. In a world of darkness, appearances are almost entirely insignificant, as prey and predator alike perceive their surroundings with sound, smell and touch, as well as other more remarkable senses like thermo- and electroreception. As such, mimcry revolves around these senses: not even a vaguely-similar imitation to a sighted creature, but a deception at least sufficient to trap its equally-blind prey.
Of the various small daggoths that populate the caves, however, none are as divergent and unconventional as the maggoths: a lineage of neotenic descendants of the mossmulch, a more typical-looking daggoth whose life-cycle has taken unexpected turns to produce one of the greatest regressions in complexity second only to the shroomors.
Measuring only a centimeter or less, the maggoths, such as the basal lichen maggoth (Vermimys simplisticus) are extremely simplified creatures: their respiration takes place almost entirely through their permeable skin, their skeletons, save for their ossified mandible and maxilla, are completely made of only cartilage, and they move entirely through two sets of muscles, an inner layer of longtidunal muscles and an outer layer of concentric muscles that contract and relax alternatingly to undulate them forward. This body plan arose from the mossmulch's early gestation lasting only a few days and producing barely-developed young, basically just self-sufficient and free-living early-stage embryos, adapted to feed constantly on meatmoss and mocklichens by tunneling through them, and, with an abundance of a reliable food source, some species eventually became neotenic, no longer developing limbs and nasal tendrils and ossified skeletons, and simply reproducing in a larger version of their quasi-larval state.
The simplified anatomy and reduction of surplus organs has allowed maggoths to be quite successful in the vast expanses of the subterranean caverns. In particular, their very simple bodies has reduced their development to but a few days, allowing them to shorten their generations to as little as three or four weeks: at the age of twenty-one days, maggoths are already sexually mature and can mate, bearing litters of up to a dozen or more wormlike quasi-larval young at a time once every five or six days. These 3-4 millimeter-long newborns feed off skin secretions made by the females for the first few hours of their life before departing for good, in a last remaining hint of mammalian history in a species so far removed from a typical mammal's form.
Another, unlikely advantage of their simplified anatomy is that it requires far less oxygen, which coupled by their incredibly small body sizes and their respiration through their skin, has led one lineage into a new frontier: the waters of the subterranearn rivers as well as the underground sumps that form bodies of water such as ponds and lakes. Thus arose the hampreys: the first ever aquatic lineage of hamsters on HP-02017 to evolve fully-aquatic respiration and thus be entirely independent of breathing air at the surface. Specialized vessels directly branching from the heart absorb oxygen diffused through their permeable skin, and thus their lungs have been reduced to simple sacs regulating buoyancy. Perhaps more remarkable, however, is the marked reduction of their nervous system, especially the brain: their simple lifestyle and unusual respiration had no need for such an energy-hungry organ as a complex brain, and thus in the hampreys this otherwise very vital organ, once the pride of mammals in their complexity, now has completely atrophied to basically but a brain stem, capable of little more than basic bodily functions and responses to external stimuli, moving through the water in jerky, wiggling movements toward the taste and scent of food and away from the vibrations of danger.
Some hampreys, such as the rasping hamprey (Vermicthymys micronis), are independent creatures teeming in the underground ponds and lakes, scraping off mats of chemosynthetic bacterial colonies using their jaws: an ossified mandible and maxilla bearing two pairs of gnawing incisors--basically the only remaining visual vestige of their rodent ancestry. Some, however, have specialized these remnant teeth for another purpose: the sanguine hamprey (Atrocivermimys haemophilus) has developed elongated teeth and a "lip" that allows its mouth to function as a suction--enabling it to attach to other aquatic daggoths such as tubesnouts and trogadiles and parasitically feed off their bodily fluids.
Not all daggoths are small, however. In the recent eons, as food and space became more available as the caverns grew and became more oxygenated, some of the daggoths began growing in size. While still small compared to outside surface animals, reaching only a maximum of 90 kilograms in the largest "grazers", their size is nonetheless an incredible achievement given their environment and evolutionary history.
The lineage that would give rise to their largest species eventually diversified into low-level grazers, higher-level browsers, generalist omnivores and specialized macro-predators. But most basal of these are the grummlers, with the largest species being the giant grummler (Macroabyssomys maximus). These represent the earliest lineage of daggoths that began expermenting with size, with them resembling the basic daggoth but simply larger. With their increased weight, their multiple digits became more columnar to support their bulk, their reduced metacarpals forming equivalents of shoulder blades to anchor powerful limb muscles, while their phalanges grew stronger and thicker and developed a bony heel-like protrusion on the second-to-the-last phalanx to support a fleshy "sole" pad: in essence turning the spindly fingers of the smaller daggoths into sixteen proper "legs".
The greater grummler is a large and indiscriminate omnivore, feeding on mocklichens, meatmoss, bacterial mats, arthropods, smaller daggoths and carrion. Depending on the species, the several species of grummlers either lean toward a more "grazer" side or a more "carnivore" side: a distinction that is less drastic than surface animals given that some of their "plant" equivalents are technically animals as well, making them more accurately "meat-grazer omnivores" or "carno-herbivores". This dietary ambiguity of this lineage would lead to the evolutionary split between the "grazers" such as the molepedes and the biblarodons, and the predators such as the blindmutts, with the grummlers themselves representing a more ancestral state of this divergence. Indeed, leaning more on the "grazer" side, the giant grummler itself sometimes falls prey to smaller grummler species with more carnivorous tendencies, especially targeted if sick, young or old.
As larger-scale predation began to emerge among the macro-daggoths, a trend akin to surface animals started to arise among them--an arms race between increasingly armed predators and increasingly defended "herbivores", with hunters specializing to take down prey larger than themselves, and large prey developing weapons to better fend off would-be assailants.
One of the most notable examples of this would be the molepedes: a clade of macro-daggoths that developed elongated bodies and short limbs that allowed them to graze closer to the ground, feeding on filamentous, low-growing mocklichens that, in a loose sense, could be considered an analogue of "grass". These slow-moving creatures were afforded ample protection by their size alone in the earlier days, but as predators too began to grow, the molepedes gradually found themselves becoming outmatched. Over time, the ancestral soft-bodied molepedes disappeared entirely, too vulnerable to the new predators, but from it emerged two lineages: the thorny molepedes and the armored molepedes.
The common thorny molepede (Echinopolypodomys spinosus) repurposed many of the sensory bristle hairs of its body into defensive spines, covering its back, its flanks and even its nasal tendrils. These spines, barbed and loose like porcupine quills, embed painfully into a would-be predator's skin and remain stuck in the flesh as they break off. As a warning, they exude a distinctive scent from specialized anal glands that previously-quilled predators quickly associate with a painful experience.
However, while an effective means of self defense, the thorny molepede's defensive spines pose a significant challenge to its other routine activities: specifically, when it comes to mating. Thorny molepede courtship is an awkward affair, with both partners releasing odorous pheromones to communicate their amorous and non-hostile intentions. Once they reach a mutual agreement, they then very slowly and gingerly back into each other, until their rearmost quills barely touch, and the male, fortunately endowed with elongated reproductive equipment, is able to complete his job from a safe distance.
A less socially-challenged relative of the thorny molepede is the armored molepede (Armopolypodomys edurus), which is a far more gregarious creature than its spiny cousin and gathers in small groups of up to ten to twenty individuals at a time. Rather than spines, the armored molepede instead has fused its hypertrophied, hardened bristles into tough keratinous scutes, which form a coat of plated armor nigh-impenetrable to the claws and teeth of its enemies. When threatened, groups of then huddle together and press themselves down, concealing their vulnerable limbs and nasal tendrils and exposing only their armored backs. Their strategy is one of persistence: eventually, after hours of clawing and biting to no avail, most predators simply give up the hunt and leave to find easier food elsewhere, and once danger has passed, the armored molepedes once more unfurl and carry on their usual grazing.
Both types of molepede tend their young with a significant amount of care until their defenses grow in, even if only passively, with their numerous litters of up to twenty young at once huddling between the adults' legs, afforded protection by their armored or spiny backs. They are, however, quite precocial, grazing and moving on their own shortly after birth, and, once sufficiently developed and defended at the age of five or six months, gradually disperse from their parent to lead an independent life.
Such defenses have become a necessity for the great grazer daggoths, as predation became more of a significant threat with the evolution of the cavern system's first proper apex predators, the blindmutts. Earlier forms simply preyed upon smaller daggoths such gothtles and xenomures, but, as prey species increased in size, so did some predators, leading to the development of some advanced blindmutts able to tackle large prey such as molepedes, biblarodons and grummlers as well.
The mandibled tendriltooth (Abyssatrox xenoailuroides) is, in the Middle Temperocene, the caverns' undisputed apex predator: even if it grows only to the size of a large house cat. Its most notable adaptation is the development of sharp, hooked keratinous spines on six of its seven nasal tendrils, which have become thick and muscular and adapted for gripping: in essence becoming six additional jaws with false "teeth". Two of its foremost digits, its central nasal tendril, and its two rear digits act as sensory feelers able to navigate its surroundings with a delicate sense of touch, while it homes in on prey with a powerful sense of smell and hearing. Once it locates its prey, it tries to grapple it with an ambushing pounce before using its six main limbs to anchor itself with its claws, and using its toothed tendril-jaws to secure a firm grip on the prey's neck before using its true teeth, sharp dagger-like incisors, to inflict a fatal bite to the prey's neck. As it targets prey larger than itself, the tendriltooth may take several days to eat its fill, and will camp out next to the carcass over the following days, fending off rivals and scavengers that may come to steal its prize. As its prolonged feeding lasts for a duration long enough for putrefaction to set in, the tendriltooth has evolved an extremely powerful set of digestive juices that allow it to continue feeding on even decomposing meat. Eventually, however, once it has sated its fill, the rotting carcass is then abandoned, and now unguarded, a buffet of scavengers then descend on the carcass, ranging from insects and worms to maggoths and xenomures to even rumptusks, vulpemousers and grummlers, all clearing up the residues the tendriltooth leaves in its wake.
Tendriltooths may reign as top carnivore, devoid of any predators of their own, yet their existence is still a precarious one, as they are few and far between given their placement on the food web. Throughout the entire cavern ecosystem, filled with millions of daggoths of different species, there are never more than a few hundred adult tendriltooths at any one time, being solitary and territorial, as they need plenty of space to sustain themselves. Tendriltooths are fairly prolific, with litters of up to twenty to thrirty tiny offspring at a time, but these small but precocial offspring, independent after only a few weeks, have a rather high mortality rate: during their early youth, where they prey primarily on insects, they are indiscriminately themselves prey for various medium-sized carnivores such as vulpemousers and smaller blindmutts, and, once they themselves graduate to medium-sized carnivore status hunting larger prey like xenomures, now have to contend with adult tendriltooths who will target the subadults to get rid of potential competition. However, should a lucky tendriltooth survive its precarious first two years, a feat accomplished by less than five percent of all juveniles, it is assured a niche of apex predator, unbothered by any other creature and with only another adult tendriltooth to fear.
