The Late Hyperpelagene

Scrupostachis (Rough Mustaches) have fully embraced their ancestor's subterranean lifestyle, evolving specialized adaptations to navigate and exploit underground resources. Their mustache-arms, already dexterous in their digistachid ancestors, have developed sharp, chitinous claws at their ends, allowing them to scrape through compacted soil, pry apart root systems, and unearth buried detritus. Their rough, scaly skin serves as both armor against abrasions and a way to retain moisture in the often arid underground tunnels they inhabit. 

When foraging, scrupostachids rely on their highly sensitive bristles, which cover their mustaches and help detect subtle vibrations in the soil. This allows them to pinpoint burrowing prey, such as small invertebrates and root-feeding organisms, before striking with surprising precision. Their clawed mustaches act as both tools and traps-some species will use them to pin struggling prey against tunnel walls, while others have evolved a raking motion to sweep up loose organic material, including decaying plant matter and poremorphs. 

Interestingly, some scrupostachid species, like Scrupostachis Eneris (Gardening Rough Mustaches) cultivate sporepore gardens deep within their burrows. By depositing partially digested plant matter in humid chambers, they encourage the growth of specialized sporepores, which they then consume. This agricultural strategy has allowed them to thrive even in nutrient-poor soils, cementing their role as ecosystem engineers of the subterranean world.

Benthostachis (Benthic Mustaches) have taken to a life of gliding just above or resting on the seafloor their ancestors, the digistachids, once lived under, resembling Earth’s rays in both form and function. Their elongated, flattened bodies allow them to ripple and undulate across the benthic floor, moving with minimal effort while staying close to the substrate. Their mutache-arms, now broad and paddle-like, serve as both sensory organs and tools for manipulating their environment. 

To survive in the dimly lit benthic environment, some benthostachids have evolved camouflage patterns that mimic the textures and colors of sand, rock, or microbial mats. Some species can even change their coloration, blending in with their surroundings much like Earth’s cuttlefish or flounders. Their eyes are positioned on the tops of their flattened bodies, allowing them to watch for threats from above while remaining mostly hidden against the seafloor.

Benthostachids are benthic foragers, feeding on a mix of small burrowing organisms, organic detritus, and microbial mats. Their wide, sensitive mustache-arms sweep across the seabed, stirring up sediment and detecting hidden prey like pleruplods, platyglosses, and small cyanophyte grazers. When prey is found, the benthostachid will use a sudden suction motion-created by flexing its broad, muscular body-to draw food into its downward-facing mouth. These foragers live in the shallows, drifting just above the benthic floor in search of food.

Like their larger relatives, the adrectastachids, Dimustachis (Small Mustaches) has successfully adapted to the deep, high-pressure environments of Atmos’s abyssal zones. However, while adrectastachids took on an upright posture, dimustachids resemble deep-sea fish, with compact, streamlined bodies that allow them to move efficiently through the water. Their small but stout frames help them withstand the immense hydrostatic pressure of the deep ocean. 

Their mustaches, extending wide from either side of their face, are critical to their survival, serving multiple functions. Lined with pressure-sensitive cells, the mustaches allow dimustachids to detect even the faintest water movements, helping them locate prey in the darkness. Some species have also developed fringe-like bristles along their mustaches, which function like nets, passively trapping drifting organic matter. Additionally, their mustaches contain a gelatinous tissue that provides slight buoyancy control, reducing energy expenditure as they hover in the water column. 

Dimustachids feed on a variety of deep-sea food sources, making them efficient foragers in an environment where resources are scarce. Like their larger relatives, they filter-feed on deep-sea sporepores, capturing drifting reproductive spores of abyssal sporepores. However, their smaller size allows them to specialize in micropelagic plankton, particularly tiny, bioluminescent organisms such as microglosses, larval tristags, and other minuscule zooplankton. In addition to their planktonic diet, dimustachids spend more time near the seafloor, scooping up nutrient-rich detritus that steadily falls from the ocean above. 

Rigiducoclis (Rigid Shells) is a line of inmoticochlids that have become entirely blind and sessile in their matrifer stage. Their early life is highly mobile, albeit planktonic, but as they mature, they gradually become more sedentary until, in their final stage, they are permanently encased within their protective shells, relying entirely on their hair-covered mustaches to gather food from the surrounding water, living lives akin to Earth's bivalves. 

Juvenilafers, their first stage of life, are small, shell-less, and free-swimming, resembling their distant mystaceverm relatives. These tiny larvae drift through the water, actively feeding on microscopic plankton. As they mature, rigiducoclids transition into the virifer stage, where they begin forming a hard, protective shell that covers most of their body. Virifers are blind and sluggish, but they still retain limited mobility, crawling along the seafloor in search of food and living by grown matrifers. They resemble their coclestachid ancestors, using their mustaches to sift through detritus and small organic particles.  

The matrifer stage marks the completion of their journey toward sessility. Once a virifer reaches sufficient size, it undergoes a final metamorphosis, fully encasing itself within its shell. At this point, they become entirely immobile, relying on their extended, hairy mustaches to capture drifting organic matter. Some species anchor themselves beneath the sand, with only their mustaches exposed to the water above, while others lie on their sides, allowing ocean currents to carry them to new feeding grounds. Some are large, and some are small. All, however, are imobile upon reaching matriferhood.

While they still rely to some degree on plankton and organic debris for nourishment, the ability to photosynthesize has granted lumevescids an edge in competitive shallow-water environments, reducing their dependence on external food sources.  This dual strategy of filter-feeding and photosynthesis has enabled lumevescids to colonize environments where traditional rigiducoclids would struggle. While other filter feeders must constantly contend with the unpredictable availability of plankton and detritus, lumevescids can persist even in nutrient-scarce waters, relying on their symbiotic cyanophytes to sustain them through lean periods. 

As a key part of the ecosystem of the shallows, lumevescids filter organic material from the water and support entire micro-ecosystems within their branching structures. Some species have developed specialized relationships with other marine creatures, such as tiny symbiotic invertebrates that clean debris from their mustaches or small filter-feeders that take shelter among them.

Panducoronis (Bowed Crowns), or "Pandis,"  are swift and nimble swimmers, darting through the water with speed and precision. Their long, arched dorsal fin, for which they are named, serves as a stabilizer, allowing them to make sharp, sudden turns to evade predators or ambush prey. Unlike their bulkier dumbocrown relatives, pandis are exceptionally social, often seen flitting through the shallows in loose, shimmering schools that move as a single, coordinated unit. 

One of their most fascinating behaviors is their “ribbon dance”-a mesmerizing display where groups of pandis swim in synchronized spirals, their arched fins slicing through the water like flowing banners. While this behavior serves multiple functions, including courtship and group cohesion, it primarily acts as a form of predator confusion, making it harder for larger hunters to single out an individual.

Repaxiscoronis (Rapacious Crowns), also known as "Raptors" are swift and voracious predators. Descended from the alacricrowns, they have taken speed and precision to an extreme, relying on their powerful propulsion system to outmaneuver prey.

Where mordeverms are pack-hunting endurance predators, raptors rely on speed, agility, and precision strikes. They use their powerful tails and crown fins to propel themselves toward their prey at high velocity, swallowing it whole in a single, rapid movement, as raptors possess no teeth. While raptors dominate in the realm of speed-based ambush predation, mordeverms excel in persistence hunting and cooperative takedowns. This divergence in hunting styles allows them to coexist in Atmos’s oceans, minimizing direct competition.

One lineage, Perritosrepaxis (Odd Raptors),  abandoned active hunting in favor of an ambush-based strategy, lurking motionless in the sand and waiting for prey to pass overhead. Their bodies have grown plump and lethargic, sacrificing speed in favor of energy conservation. Their mouths have expanded disproportionately, allowing them to engulf large amounts of water-and, ideally, prey-in a single strike. However, the true oddity of perritosraptors lies in its method of attack: rather than lunging forward with traditional musculature, it uses a powerful burst of water expelled from its crown to shoot its bloated body toward unsuspecting prey in a sudden, erratic motion. 

While this bizarre adaptation allows them to ambush vorms and other small creatures, it is not an efficient long-term strategy. Their sluggishness makes them vulnerable to faster predators, and their reliance on perfect ambush conditions limits their hunting success. Over time, more efficient hunters and scavengers outcompete them, leading to their eventual disappearance from Atmos's seas.

One group of raptors, Densrepaxis (Tooth Raptors), has adjusted its hunting strategy, making them far more formidable predators. While early raptors relied on sheer speed and suction to swallow prey whole, densraptors have evolved a sharp, spear-like tooth at the tip of its elongated mouth. This adaptation allows it to stab and impale prey mid-pursuit, preventing slippery or agile creatures from escaping its grasp. 

The evolution of its spear-like tooth allows densraptors to pierce through the soft bodies of smaller organisms or deliver a decisive stab to the vital regions of tougher prey. This adaptation greatly expands its menu-densraptors are no longer restricted to tiny, easily swallowed creatures but can now target larger, more resilient prey that would have previously been out of reach. 

Its behavior and hunting tactics have also evolved in response to these physical changes. Unlike the rapid, darting strikes of its toothless cousins, densraptors stalk their targets more carefully, often tracking them for brief moments before launching a devastating burst of speed. It uses its powerful crown-fin propulsion system and muscular tail to close the distance in a matter of seconds, delivering a precise, high-speed thrust of its tooth into its prey before letting the struggling victim weaken.

Iuvenalelaruis (Youthful Ghosts), or "Infants," are a of neoteny-driven parasitism, mimicking the juvenilafer stage of their conmuniaruid ancestors to exploit the communal nesting system. Rather than undergoing the typical transformation into virifer or matrifer stages, infants retain their juvenilafer morphology throughout their entire lives, reaching sexual maturity while still resembling helpless young. 

This deceptive strategy allows them to blend in seamlessly with the true juvenilafers of conmuniaruid colonies, avoiding detection while benefiting from the colony’s protection, food resources, and care. The virifers, tasked with raising the next generation, unknowingly invest time and resources into these impostors, mistaking them for legitimate juvenilafers.

Crasiostis (Fat Mouths) is a massive, slow-drifting descendants of the ostiverms, having further specialized for their ancestors’ mouth-agape filter-feeding strategy. Their cavernous mouths allow them to gather enormous volumes of water for plankton, spores, and organic debris. Unlike the more active feeders of Atmos’s oceans, crasiosts are nearly passive in their foraging, relying on ocean currents to bring food directly into their gaping maws. 

Their bulk and buoyancy make them gentle giants of the sea, slowly gliding through nutrient-rich waters with minimal effort. Despite their passive nature, crasiosts are remarkably resilient, with thickened, blubbery bodies that deter most would-be predators. Like their ancestors the ostiverm, many species have developed symbiotic relationships with smaller scavengers, which clean debris from their filtering structures in exchange for protection and a steady source of food.

Rhynchostis (Nose Mouths) are a lineage of ostiverms which have evolved an enormous, fleshy “nose.” This structure, a thick pad of fatty tissue above the upper lip, serves no role in feeding but has become a critical element of sexual selection and dominance displays. 

Among virifers, the nose is both a status symbol and a weapon. Larger, more pronounced noses indicate health and strength, making individuals with the most exaggerated features more attractive to mates. During the breeding season, rival virifer rynchosts engage in head-to-head shoving contests, pressing their bulbous noses together and attempting to push each other backward. These contests help establish dominance hierarchies without resorting to lethal violence, similar to how elephant seals or certain deer species on Earth use physical contests to determine access to mates. Upon becoming matrifers, a rynchost's nose will typically atrophy, becoming smaller and less prominent.

Piscatauris (Catching Centaurs) is a lineage of stocky, heavily armored ambush predators descended from the centauriplods. Their thick shells provide both protection and effective camouflage against the rocky seabed and sediment-covered hunting grounds where they lurk. Their reddish-orange coloration, reminiscent of some crustaceans on Earth, helps them blend into their environment, making them difficult for prey to detect. 

Piscataurs have evolved highly specialized limbs suited for their voracious vormivorous diet. Their lower arms have elongated, becoming long, dexterous appendages capable of swiftly snatching unsuspecting vorms from the water. Once captured, vorms are drawn toward the piscataur’ short, robust pincers, which grind and tear apart their meals before consumption. 

A typical piscataur hunt is an exercise in patience and precision. These ambush predators remain motionless, nestled among the rocky seabed or buried partially in the sediment. Their stocky bodies remain hidden, while their long, spindly lower arms stretch outward, waiting for an unsuspecting vorm to wander too close. 

When a vorm unknowingly drifts within reach, the piscataur strikes with astonishing speed. Its elongated arms snap shut around the prey, pulling it inward toward its compact but powerful short pincers. These pincers quickly crush and masticate the struggling vorm, breaking it down into digestible pieces before the piscataur finally consumes it.

Caesitauris (Blue Centaurs) is a lineage of small, upright centauriplods that have found success in the cyanophyte meadows of the shallows. Unlike their stockier, ambush-hunting relatives, the piscataurs, the caesitaurs have taken on a tall and broad posture, allowing them to maneuver easily through dense cyanophyte growths in search of food. Their mineralized spinal shell, a hallmark of their lineage, provides them with protection while allowing for flexibility and mobility as they navigate their habitat. 

These small creatures are specialized diggers, primarily feeding on poremorphs which thrive in the soft, nutrient-rich sediment of the meadows. Their lower arms, once adapted for grasping, have become more robust and shovel-like, allowing them to dig into the substrate with precision. Their upper pincers have similarly evolved, functioning as secondary digging tools as well as effective implements for grasping and consuming prey. 

Living in the shallows, caesitaurs are diurnal creatures, relying on their keen vision to spot disturbances in the sand that indicate the presence of burrowing poremorphs. Their blue coloration, from which they get their name, serves as camouflage among the cyanophytes. Though they are primarily solitary foragers, they will tolerate the presence of others in highly productive feeding areas, occasionally engaging in claw-waving displays to establish foraging boundaries.