Europan Ecosystems

Early exploration missions used melter probes to bore through the ice to reach the (then theorized) salt ocean below. These probes were designed to send out remote vehicles for aquatic exploration below the moon’s surface. The first probes sent back nothing but images of a massive, lightless ocean, punctuated only by an occasional “snowfall” of heavy salt-laden ice particles from the inner surface. Those commanding these first missions assumed that the most promising location for non-Earth life was sterile. They were wrong.

On Earth, the top was sunlit and relatively warm (even near the poles) and the deeper parts were dense and cold. Europan oceans is the opposite since the warm currents come from hydrothermal vents along the floor so the warm, flowing water is near the bottom and the cold, dense water is near the top. This accounts for the earliest observations of the subcrustal ocean (discussed above) which sampled only the relatively empty upper ocean. Dr. Penelope Tarrison's work in exploring the deeper sections revealed that the ocean depths extend down 100 km in some places, deeper even than the Marianas Trench on Earth. In these depths, towering lithodermic reefs form pseudo-mountain ranges and create varied ecosystems for the abundant deep-ocean life.

Author's Note: Most of the entries here are from either published Eclipse Phase sources or sourcebooks for the Blue Planet RPG, notably the Moderator's Guide and Natural Selection.

Common Ecological Terms

  • Ana: Fish-analog species. These species form the bulk of Europan biomes, like fish in Earth’s oceans. Anas have two rows of multiple eyespots running head to tail along their flanks, and they appear most sensitive to infrared light. The typical body form is more elongated than the average terrestrial fish, lending a distinctly eel-like motion to anas swimming. Ana gills are physiologically similar to those of Earth fish, but are couched in slits running the length of the animal's body, just below the row of eyespots, with thin undulating muscular flaps to keep them supplied with fresh water. Most species have two sets of jaws - a secondary, horizontal set on the sides of the primary, vertical jaws. This gives ana mouths a characteristic four-part structure.
  • Haploid: The type of genetic reproduction found in many Europan organisms as well as fungi on Earth. Haploid organisms can reproduce sexually, with two organisms contributing genetic materials, or asexually, with spores originating from one.
  • Hexipedal: Six-legged. A number of non-swimming species on Europa are hexipedal, including the hellbenders commonly seen clinging to the ice around Pwyll and Connamara.
  • Medusoid-stage: Many Europan species reproduce through a stage similar to the medusae of Earth cnidarians (jellyfish, anemones, etc). On Earth, the medusa stage is the immature, mobile stage of animals like jellyfish which further develops into the mature adult. Europan species follow this model but they are morphologically different: long, ovoid forms with lines of cilia down the side to propel them.
  • Microkrill (Order Pseudophausiacea): These microscopic creatures, found from the abyssalpelagic to the mesopelagic zones, resemble something between Earth krill (crustaceans) and mold colonies. Individually, they are on the order of micrometers (a thousand times smaller than Earth krill) but they band together into large rafts that can be up to 2 centimeters in length. Colloquially, microkrill is also used to describe all the small-scale organisms in the Europan oceans, including the medusoid-stage of larger animals.
  • Tetramaxillan: Four-jawed. The vast majority of Europan fish analog species have four jaws: two for biting and holding and an inner two for chewing.

Epipelagic Zone

Subcrust to 10km Depth
The Shallows, the Subcrust

On Earth the epipelagic zone of the ocean was characterized by increased sunlight and life, but on Europa it is characterized by cold and empty waters. The heat in the Europan oceans comes from the hydrothermic vents at the bottom of the ocean so the upper levels are the coldest. Consequentially, they are also unable to hold dissolved salts as well and thick brine deposits form along the underside of the icy crust and on the ships and habitats of transhumanity. When the brine frost becomes too thick it will tear loose and fall into the depths, carrying a shower of ice with it. This is usually not much of a hazard for submersibles or synthmorphs, but swimming biomorphs and podmorphs can be seriously injured by the chunks of ice and salt.

Big Round Thing


BRTs are a recently-discovered enigma on the ice surface east of Tethys Cluster. In the initial publication of their discovery they are termed Mat Colonies, but a lifelog from one of the discovering scientists has come to dominate the conversation. Most people have heard mesh reports by now of the “Big… round… things!” broadcast and call them BRTs or Rounders. They appear to be some form of superorganism that is actually a collection of smaller units that some xenobiologists argue should be classified as separate species. These subunit organisms are seldom encountered independently, however, and in captivity quickly enter a state of dormancy that invariably precedes death. This implies that the organism is not simply a colony of individuals, but an organic manifestation of the physiological interdependence of its smaller units. There are a variety of these subunit forms, though beyond subtle differences in shape and coloration, the uninitiated find them difficult to tell apart.

Europan Hellbender

Os venenifer

Hellbenders are named after the large Earth salamanders they vaguely resemble. Unlike their namesake, Europan hellbenders are hexipeds, have a dozen ruddy-colored eyespots along the length of their marbled brown backs, and possess a segmented shell similar to an armadillo’s over most of their bodies. The animals have feather-like external gills and tails which are long and laterally compressed making them very efficient swimmers. Their feet are long toed and tipped with small claws that they use to latch into the ice undersurface where they spend a significant amount of time waiting and sifting microkrill from the water. Europan hellbenders are mostly seen around Conamara and Pwyll where they skuttle across the ice and often disrupt external equipment. Explorers who aren’t careful might accidentally disturb these creatures when navigating the icy stalactites, and hellbenders can be surprisingly dangerous when provoked.

Grip Vine

Vinea carpo

Grip vine is a troublesome aquatic growth that poses a nuisance or hazard for submersible vessels depending on the size of a particular patch. Grip vine is a thick-stalked, kelp-like species that is common in temperate, mesopelagic areas. The algae analog has bright orange fronds with mottled brown stalks, and grows in large anchored patches that form tangled thickets in quiet areas.

Mesopelagic Zone

10km to 40km Depth
The Mid-Ocean, the Tops

The mesopelagic zone encorporates the tops of the lithodermic reefs and their upper peaks. It is where nearly all of the habs not directly attached to the ice are located, the barnacle habs that are anchored to the reefs themselves. Though nutritionally poor compared to the lower sections of the ocean, they are also free of strong currents and violent thermals. Xenobiologists have identified the most number of species from these depths, though this is more likely due to the increased observation than because they are any richer in life. Still, there is a wide range of creatures at these depths and some of the most well-known analog species can be found in the mid-ocean.

Mid-Ocean Reefs

Class Lithakmaza

Microscopic lithoderms, analogous to Earth’s coral species, have formed vast mountains and forests of Europan coral throughout the depths. In the mid-ocean, lithodermic reefs resemble mountains more than coral reefs in terms of Earth’s features. Many divers thought that they were simply geologic features for a long time and even after xenobiologists had published studies on the lithoderm organisms, off-world scientists resisted their claims until the more organic abyssal lithoderms were documented. Mesopelagic lithoderm species are slow-growing, on par with Earth’s coral polyps, though they have ready access to oceanic ions to build their habitats with. The low temperatures of the waters where they grow, however, and the severe slopes that can develop in Europa’s slight gravity mean that mesopelagic lithoderm colonies are in constant danger of collapse. Because most of the barnacle habs on Europa are rooted on these structures, knowledge of their strength and stability is very important and has been gained at some expense, as the ruins of Atlantis in the New Hawai’i chain can demonstrate.


Medusus bolatus

Many of the animal-analog fish have an immature stage in which they resemble fungi before metamorphosing into free-swimming adults. One such is the bolatee, a five-meter long schooling creature that grazes on tiny microkrill with branching masses of tendrils that resemble roots or jellyfish tentacles. While large, mobile, and exhibiting some animal-like behaviors, the bolatee has a rudimentary nervous system and reproduces with spores.

Chain Beetle

Dorsalis givenis

Chain beetles are actually not insectoids, nor are they crustaceanoids as their amphibious behavior implies. Their phylogeny is unclear, but they appear to be some sort of large mollusk-analogs with chitonous coverings over their pseudopods. They vary in size, but individuals can grow rather large, and colonies can reach more than five meters in length. Their coloration is cryptic and typically matches the muds and sands in which the animals commonly bury themselves. Their bodies are flattened dorsa-ventrally and their shells are extremely thick and strong. The creatures' four lateral limbs are used for locomotion, and a pair of strong ventral appendages are used for collecting and processing food. Alternatively, they can latch on to another chain beetle to form long colonies that move like one centipede-like creature to hunt. One chain beetle is not much more than a nuisance to a transhuman, but a chain of them can cause significant damage if surprised enough to lash out.

Digger Crab

Cancersimila fossionis

While crabs are the nearest comparison as far as Earth species in terms of ecological niche, they more closely resemble a cross between sea urchins, lobsters, and isopods: a spingy, round body which is armored with large chila (pincer claws) and compact legs which lend it a scuttling motion. Two rows of eye pots flank the crab laterally, but its primary sensory organs consist of a series of antenna along its legs. The female is as much as three times again as large as the male, and lacks the carapace common to most terrestrial arthropods. Functionally little more than an egg factory, the bloated, soft-bodied female suffers from limited mobility and underdeveloped eyespots.

Europan crustaceanoids have several life stages: a medusoid stage, a sexually-active intermediate stage, and an adult stage. During the intermediate stage, digger crabs exhibit sexual dimorphism and mate, though the specifics are still under study. Once the crabs have procreated, the equivalent female of the pair carries the nascent spores and spends much of its time resting deep within the maze-like tunnels constructed by her multiple male partners in the upper reaches of the reefs. The third, fully mature stage of the organism is of moderate size (between the large females and smaller males) and spends much time hunting in the area around warren-nests. Its most common prey includes insect analogs. smaller crustaceans, and other invertebrates. There seems to be a symbiotic relationship between this stage and the sexual intermediate stage as the male drones get a significant amount of their food from the scraps of the mature stage.


Piscis refero var.

Echo/fish is the interspecies name for a genus of related ana species that inhabit the mid-level reefs close to the Haven and Zion habitat clusters. The various species have names in Neo-Cetacean which translate to collections of concepts like soft/swift/diver/twitch/soft and bony/rough/speeder/juice/bony, but among other transhumans they are generally lumped together as “echo/fish.” Neo-cetaceans generally find the inability of other transhumans to readily distinguish between these species (even with the aid of echolocation) to be baffling and many are always ready to offer long explanations of the nuances of their acoustic signatures, swimming habits, and textural variations. Transhuman psychologists believe that this ongoing discourse is a subtle commentary on the physical limitations of non-cetaceans that the Mercurial community finds humorous and counter-cultural.

Echo/fish range in size up to a quarter of a meter and share basic elements of shape and color. Most species are some version of silver, gray, or brown, and have what could be considered the archetypal body form for Europan fish analogs: long, sinnuous bodies with multiple jaws and linear eyespots. Most live in large schools and are found throughout the Haven-Zion region and beyond.

Gladiator Crab

Cancersimila preliator

The gladiator crab is a large crustacean analog whose name comes from its single-minded territoriality. The animal is believed to be a close relative of the digger crab and is the most heavily shelled and densely muscled of Europa’s poorly-understood crustaceanoid species. Sporting comically large chila, or pinching claws, and an unusually thick carapace, the gladiator is a formidable animal that is typically eaten by only the largest and most determined predators.

Greater Rewera

Timore dominatus

Along with the mazimus, this is one of the planetary apex predators of Europa. They are long and lean with sharp teeth which invites comparisons to sharks, but their physiology is much closer to an elongated octopus than a fish. The rewera’s six tentacles wrap together while swimming to make a whip-like tail that allows it to swim quickly after prey. Once prey has been secured in its jaws, the rewera unwraps its limps to wrap around the creature and pry it open. The rewera is particularly adept at wrenching past the armored plates of some ana species with its tentacles, but it also can use these to pry open the hardsuits and submersibles of transhuman colonists. The greater rewera has a terrifying reputation as a result, which earned its common name (“devil” in Maori).

Lesser Rewera

Timore timore

The collective term "lesser rewera" refers to any of a dozen smaller relatives of the greater rewera which fill many of the ecological niches of Earth’s smaller sharks like dogfish and bramble sharks. Around the New Hawai’i Cluster they are particularly common and significant both ecologically and economically. Many are well known to the natives and carry common names like surf cutter, black back, and red devil. These animals vary greatly in size, behavior, and superficial physical characteristics, but they share a basic anatomy and predatory ecological role.


Tripudio tripudio

Peke-peke is the local name for a common ana species that forms large schools near the New Hawai’i chain of habitats. These animals range in size, but seldom exceed two kilograms. They are nondescript and grey, though some have reddish or yellowish hues to their fins. They stand as examples of typical Europan tetramaxillan anas, and have little to distinguish them save their abundance and their domestication by colonists in the New Hawai’ian chain. Peke-peke forms a large part of some colonist diets, and makes up a large portion of the fish-analogs consumed by Europans since it is one of the few species to be regularly harvested. Peke-peke flesh is yellowish and flaky when cooked and has a nutty flavor that is an acquired taste for most transhumans with typical taste buds. Soaking the uncooked meat in clean salt water makes the fish more palatable to the average newcomer, but is considered a crime by New Hawai’an cooks.

Reef Serpentis

Serpentis cautes

The serpentis is a large species of predatory ana known for its exceptional speed and clever huntsmanship. The serpentis is streamlined and flexible with a well-muscle, eel-like body that can reach up to two meters in length. The animal's primary jaws are long and narrow and lined with dozens of serrated teeth. The species lateral jaws are wide and sport razor sharp bony spurs along their outer edges. The serpentis specializes in hunting among the twisted spires of the lithodermic reefs where its flexible body allows it to follow smaller ana species into their hiding places. In places where its territory overlaps the mazimus mazimus’s, the serpentis also uses its flexibility defensively, to stay out of the larger predator’s way.


Ambulo infitialis

The wraparound is a nasty parasite that is occasionally found in various species of anas. As the parasite grows in length, it coils repeatedly around its host's notochord, drawing nutrients from the animal's body fluid by osmosis. When it reaches sexual maturity the worm embeds its posterior end into its anterior aperture, and the two ends of the coil quickly grow together, fusing the creature into a seamless helix. The worm then asexually produces thousands of tiny eggs that fill its own body structure, eventually killing it and causing significant neurological damage to its host. The wraparound parasite has proven very dangerous as it is the only Europan organism known so far to survive in terrestrial species, including transhuman morphs. Luckily, the wraparound is only transmissable by eating infected species and cooking it will kill it. Even if a morph does contract the parasite, basic biomods will find and counteract its growth until it can be purged with medication.


Peloris vergrandis

Xenosilicabenthoids, or X-clams, are innocuous benthic invertebrates that are relatively unremarkable except as a nuisance and hazard. These small animals are best described as a cross between an urchin and a bivalve. The organism has a two-part spherical shell hinged at the dorsal edge and cover in thin spines that can eject a painful neurotoxin. Its internal body consists of a visceral mass and a snail-like muscular foot, the entirety of which can be sealed within the ball-shaped shell. The species is geographically limited to the reefs southwest of Westcape Cluster, although cross-contamination by submersibles is always a danger.

Bathypelagic Zone

40km to 70km Depth
The Deep, the Bath

The bathypelagic zone about halfway to the ocean floor is about as far as most colonists on Europa have gone. It is a dark place full of extreme currents as the warm waters of the abyss flow up and trade places with the cold water of the subcrustal ocean. Consequently, it is the level known as the Deep despite the fact that there are forty kilometers on average until one reaches the seafloor.

Deep Reefs

Class Lithakmaza

The root of the lithodermic reef mountains is a place of large-scale formations of amazingly vibrant lithoderms and dead zones of rubble and waste. The deep waters of the abyssalpelagic zone are some of the richest in terms of mineralogy and the lithodermic species that live there can create shells of material at astonishing speeds for those who still think of these creatures as basically coral. Xenobiologists leaving navigational markers often find them covered with 3-4 cm of new growth just a few months after emplacement. Counteracting this growth, however, are large blocks falling from slope failures above and pressurized explosions from vent networks below. Both serve to destroy lithodermic colonies in this area meaning even more turnover for the landscape.

Aurora Borialgae

Autus fervens

Aurora Borialgae is the unfortunate common name for one of the more spectacular species of parastitic organisms growing on Europa’s lithodermic reefs. The species has only been seen in great numbers in the region around the Westcape Cluster, though xenobiologists have reported samples of borialgae or similar species to the south as well. Borialgae is a protist analog, though it is colonial and has some features in common with blue-green algae (cyanobacteria). It grows at shallow depths, in high-salinity, nutrient-rich waters near sites of deep-ocean upwelling. Colonies of borialgae grow in massive, monogenetic patches across lithodermic reefs that can stretch for kilometers. It gets its common moniker from its extreme conductivity, owing to its high salt content. Colonists in the Westcape region discovered by accident (according to a dozen local stories) that a moderate electrical current applied to the patch will cause a bioluminescent discharge through the entire colony. The individual organisms are small, fleshy clusters that surround themselves with crusty, interconnected shells made of ions extracted from the lithodermic reefs, and these connections are primed for conducting electrical currents as well.

Barrister Fish

Mellisus kopilatus

These fish-analogs are actually invertebrates with a rudimentary nodal chord, resembling a combination of sea cucumbers and eels. They spawn through a medusoid stage which hides among the hive colonies built by the adults. Barrister fish create their colonies by gathering sediments and fragments of the lithodermic reefs then mixing them with an extruded mucus which hardens into tunnels and chambers for the medusoids to live and hunt in during their first few months of life. Several different adults can contribute to a hive with medusoid young from many different pairings coexisting. Once they reach adult stage, however, the medusoids prey on each other as much as microkrill and small anas.

Blood Hunters

Venator cruentus

Blood hunters, or hunters as they are more commonly called, are voracious fish analogs that inhabit the deep waters in the valleys between lithodermic reefs. These anas fill a niche similar to piranhas: schooling, carnivorous creatures that mob their prey and protect each other with numbers. They are dark green to black with an iridescent sheen from a sort of conductive mucus of unknown purpose. They are sleek bodied, fast swimmers with two rows of exceptionally sharp slicing teeth on each of their four jaws.



Xenobiologists have only gathered a few samples of this creature for study and many questions still abound. Resembling small lancelets, rarely more than a centimeter or two in length, gelfingers can be found among the worn sands of the lithodermic reefs and are somewhat difficult to locate and study. Gelfingers are sometimes found individually and sometimes as mucus-covered clusters, and there is significant variation in shape and size. Currently, there is much debate about whether gelfingers are larval or adult creatures and whether they are a single species or several different ones which only resemble each other superficially.


Mazimus tromosus

This five-meter ana resembles an Earth viperfish, though it is roughly ten times the size of that animal (adults reach 3 to 5 meters). This predator is capable of attaining swimming speeds in excess of 55 kph and biting through plate steel up to 2 centimeters thick, making it one of the most dangerous creatures in Europa’s depths yet discovered. The long, curved teeth of the mazimus would be relatively fragile if they were made of something like bone but the mazimus’s teeth contain a significant amount of the metallic ions found in Europa’s oceans. The result is a hard tungsten-rich material which gives the ana its powerful bite.

Sea Seraph

Poena maris

These ctenophore-analogs drift through the ocean currents, planktonic sifters feasting on microkrill in the lower, warmer waters by Tethys Cluster. They have flat, transparent bodies and pairs of wing-like paddles that help them to maneuver between currents, although they tend to follow the dominant flow. hen they catch the light from submersibles, iridescent colors shimmer across the paddles, ostensibly giving the species its name. The reason for such irridescence on a lightless world is still a matter of discussion. Angel wings typically hang vertically in the water, trailing a short, thin mass of tentacles as they drift with the current.

Abyssalpelagic Zone

70km to 100km Depth
The Abyss, the Dark

Abyssal Reefs

Class Lithakmaza

The root of the lithodermic reef mountains is a place of large-scale formations of amazingly vibrant lithoderms and dead zones of rubble and waste. The deep waters of the abyssalpelagic zone are some of the richest in terms of mineralogy and the lithodermic species that live there can create shells of material at astonishing speeds for those who still think of these creatures as basically coral. Xenobiologists leaving navigational markers often find them covered with 3-4 cm of new growth just a few months after emplacement. Counteracting this growth, however, are large blocks falling from slope failures above and pressurized explosions from vent networks below. Both serve to destroy lithodermic colonies in this area meaning even more turnover for the landscape.

Europan Leviathan

Europus tarrisoni

The first transhuman to personally visit the ocean below the surface of Europa was Dr. Penelope Tarrison, a biological oceanographer from the Woods Hole Oceanographic Institute. Her initial descent occurred in a custom synthmorph designed to withstand aquatic pressures far greater than any experienced on Earth. During a later incursion, she descended to the very ocean “floor,” a dense slush of water ice punctuated by thermal vents and the towering edifices of endolith coral. There, she encountered what is thought to be the largest Europan life form, the europus tarrisoni—the Europan leviathan. A sleek, streamlined creature twenty meters in length akin to a vampire squid, it fills the same role as Earth’s whales, screening microscopic and small macroscopic organisms from the ocean for food.

Sea Ghoul

Voro inferi

In keeping with their name, ghouls are ugly creatures, with mottled gray and white skin. They have segmented legs which they use to cling to the lithodermic reefs and crawl across it but also flapping, wing-like fins that they can use to swim in a swooping fashion. Ghouls prowl the peaks of the reefs in search of dead creatures to scavenge, pulling their catches into small caves to eat. Particularly large corpses can gather packs of the creatures, scuttling over the body and pulling it apart while their corpse-like flaps shuddering in the frenzy. Their small jaws match their small heads, but are tipped with pairs of bony plates that can saw effectively to cut through most biological materials given enough time.



Serious xenobiologists have always considered stories about the so-called singer-in-the-dark just tales to tell in the bar after a voyage. Europan mesh sites and lifelogs are full of references to the “singer-in-the-dark”, or the “night singer” from the earliest days of colonization. Many deep-ocean navigators swear they have heard the creature's haunting calls or knew someone who was lost to a singer particularly solo voyages through the deeper parts. The only feature consistently attributed to singers-in-the-dark is a mournful, strangely beautiful song. The descriptions in the available stories vary, but the call is supposed to be low and musical, carrying through the Abyss. The singer-in-the-dark has a significant mesh presence and is something of a local celebrity for Europans.

Hadopelagic Zone

Below 100km Depth
Hades, the Lightless Black

Hydrothermal Zones

Anywhere 60km to 100km depth
The Vents

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