The life forms of Ilmatar are a rich and diverse ecosystem completely unlike anything on Earth.
The fundamental energy source for life on Ilmatar is hot, mineral-rich water flowing from seabottom volcanic vents. All life on Ilmatar ultimately depends on these vents. Organic compounds rich in phosphorus and sulfur support microscopic organisms in the water, which conduct chemosynthesis to power their metabolic systems. Most species on Ilmatar are single-celled chemical-feeders.
Larger multicellular organisms feed on the single-celled life, either by filtering seawater near vents, or by scouring rock surfaces. By common convention, we refer to the immobile filtering organisms as "plants" and the mobile scourers as "animals" although genetic studies suggest they are often closely related.
At the top of the food chain are large predators, including the intelligent, social, tool-using beings we call "Ilmatarans."
The intelligent, tool-using beings of Ilmatar have the species name Salletocephalus faber. The name literally means "helmet-headed builder." When Ilmataran settlements and structures were discovered by drone cameras, scientists were initially unsure if their constructions were consciously-planned architecture, or instinctive constructions like anthills or bird nests. The question was resolved as soon as humans observed Ilmatarans working in organized groups, making and using tools, and engaging in what appears to be economic specialization of labor.
An adult Ilmataran is typically 3 to 6 meters long. Larger individuals have been spotted, but they typically are solitary and may be a different species. There is no visible distinction between male and female Ilmatarans.
An Ilmataran's body is covered by a rigid, segmented shell, which gives them a superficial resemblance to Earthly crustaceans. At the front is a large, domed head which serves as the Ilmataran's echolocation organ. They apparently use their echolocation ability for communication as well as sensing their environment.
On the underside of an Ilmataran's head is the mouth, surrounded by 7 rough-textured feeding tendrils. These scrape bits off of whatever the Ilmataran is eating, and convey it into the mouth. The two segments behind the head have limbs specialized for manipulating; they resemble the forelimbs of a praying mantis insect. Behind those are four pairs of walking limbs. The tail has broad horizontal flukes, for use when swimming in open water.
Ilmatarans reproduce by spawning: a female lays a clutch of eggs, which are then fertilized by whichever males come along. There may be some social constraints on which individuals may do so, but that isn't well understood by humans yet. Young Ilmatarans don't get much parental care after they hatch, and most wander off to the periphery of settlement areas until adulthood. The survival rate among juveniles is low.
Their anaerobic metabolism means Ilmatarans (like other organisms on their world) tend to engage in short bursts of intense activity rather than long, sustained effort. They are more active in warm water than cold.
Ilmatarans apparently live a long time. Isotope assay of Ilmataran remains suggests a lifespan greater than 100 years.
Humans have only studied a few Ilmataran settlement sites, and then only by remote sensing devices, so our knowledge of their society and culture are very limited.
We do know that Ilmatarans make and use tools. They employ a wide variety of materials: stone, animal and plant tissues, and shells. Some of the animal and plant materials appear to be "cured" or "tanned" using heat or chemicals. Metals are entirely absent, due to their scarcity in Ilmatar's crust and the lack of combustion for smelting.
The Ilmatarans are highly adept at working stone. They build large structures, including domes and arches, and construct elaborate systems of pipes around thermal vents to capture and circulate the rich hot water.
They cultivate a large number of other organisms. Settlements cluster around thermal vents, and the pipe networks convey nutrient-rich water to a variety of sessile organisms. These "farms" are the basis of most Ilmataran settlements. Other Ilmatarans catch free-swimming animals, and sometimes "herd" groups of them. They employ the large Kolympidelta for towing cargoes or groups of Ilmatarans.
We currently do not know very much about Ilmataran society. They form communities, but we know nothing of how they govern themselves or resolve conflicts. We believe they are capable of keeping and passing on knowledge, but we don't know how that is done.
We can see what the Ilmatarans make, and watch them from a distance as they go about their work. But what they think, what they believe, and what they talk about are still a mystery.
You can learn more about Ilmatarans and their culture at the Carl Sagan Institute for Xenology Web site.
Other Ilmataran Life Forms
Abroxyrum: a small (10 cm.) shelled organism, with very sharp bladed claws.
Absolophage: a flat circular animal 1-2 cm. across, which feeds directly on carbon compounds near seafloor vents. The largest purely chemosynthetic organism known.
Abyssoptyon: A sessile "plant" shaped like a large fan, sometimes up to 10 meters in diameter.
Achroiamphiblestrum: A common filter-feeding organism which floats freely in the water but has no way to propel itself. It resembles a network of pale fibers, up to 5 meters across.
Aenocampus: The largest and most dangerous predator in the Ilmataran ocean, Aenocampus has an armored body 10 meters long, equipped with a cluster of sharp claws.
Aethalophage: A family of very common microorganisms found in the hot water plumes above seabottom vents.
Astacomorph: The name given to the large family of Ilmataran segmented organisms with external skeletons.
Benthosestrum: Another sessile "plant" related to Abyssoptyon, it resembles a net anchored to the seabottom, typically 1-2 meters across.
Cnestodactyl: A small, shrimp-like scavenger, sometimes as big as 10 cm.
Corydocephalus: A species apparently related to the intelligent Ilmatarans, resembling a 1-meter lobster with a bulbous head.
Cylindrodaptes: The largest mobile organism in Ilmatar's ocean, it is a filter-feeder with a huge, open-ended tubular body. Some are as big as 6 meters across and 20 meters long.
Echinoartamous: A small (20 cm.) but dangerous predator armed with sharp claws.
Echinosacus: A 1-meter bottom-dweller, possibly related to Absolophage, with a circular body topped by sharp spines.
Ethmonectris: A common mobile filter-feeding organism, it has a tube-shaped body about 1 meter across and 2 meters long.
Kolympidelta: A large (5-meter) flat-bodied organism which swims by rippling its delta-shaped body, much like a manta ray. Possibly related to Tachyagreus. Ilmatarans have been observed using Kolympidelta as a "beast of burden" to tow loads.
Laematohelix: A sessile filter-feeding organism, this grows in dense thickets of coiled fibers, which may sometimes entangle large mobile organisms.
Megalonetrum: A large filter-feeder with a spindle-shaped body about 10 meters long, covered with trailing filaments.
Ocypsalis: An active "pouncing" predator about 2 meters long, with unique scissors-like claws.
Oncioglottis: An unusual soft-bodied predator about 50 cm. long, using a barbed tongue-like structure to capture prey.
Psammoclyster: A very common seabottom filter-feeder, it has a simple tube-shaped body and tunnels into the silt to create a U-shaped burrow.
Sagomeniscus: An armored rock-scourer about 2 meters long with a distinctive crescent-shaped head.
Tachyagreus: One of the fastest organisms on Ilmatar, this creature strongly resembles a 2-meter manta ray.
Theiotroph: A family of very common microorganisms, found throughout the Ilmataran ocean.
Xysterobrachium: A 20-centimeter rock-scouring organism with large rasping claws.