Ecologies of Space

Students of cosmobiology should be aware that there is no exhaustive textbook on the subject. Space spans a dazzling array of extremes: bitter cold of void; fuming chaos of reentry; irradiant calm of an unshielded sun. Threat and boundless opportunity form a darwinian brawl that, plighted by human genetic meddling, holds form too bountiful to count.

Even the largest long-haul ships would struggle to maintain this diversity in vacuum;
this sample is from the liquid core of a comet mine in the house of Taurus

The primary categorisation for a newly discovered lifeform denotes the source of its energy supply.

The most common 'pest' organisms on spacecraft are chemotrophs, and these complex habitats are where they are most commonly found. They may take their energy from raw chemical sources, like the rainbow varieties of plastic-eating bacteria and shipworm. Others prey on other organisms, be they herbivorous teacup crabs or the voracious glass eel. Not all are considered pests, however. Barnacles are often assumed to be a sign of smooth reentry and good luck. Cheaper than a mechanic is a box of shipwright 'mites, dumped into damage to help patch leaks (though they'll eventually hollow the whole hull into an airy nest). 

Chemotrophs are characteristically the organisms most complex, most embedded in their ecosystem, and least likely to survive solar flares, dust storms and reentry. Some simply hunker down into ablative, carbonised shells. Others structure their life-cycles to the schedule of their hosts, like the near-indestructible micro-elvers of many eels and the hurriedly-buried eggs of roaches. The most complex webs of life blossom when undisturbed. Long-haul ships build whole ecosystems, many of which beneficially catch and recycle light and nutrients for the use of the ship.

Phototrophs draw their life from the sun, or other radiant bodies. Some phototrophs may bask in lights on a ridden ship. Some are even grown commercially. Bamboo, potato, spacegrape; sheathed swaddles of roots projecting bizarre appendages into space. Many of those that seem to rely only on the sun in truth would not survive without the thin atmospheres of leaky, ionic spacecraft. 

The most common phototrophs are cyanobacteria, algae and lichens, with many species that are happy riding asteroids or cosmic dust, or simply spinning alone in space until they bump into a host. A growth of more than a few centimetres height is a strong indicator that the organism requires atmosphere, whether leaked from the ship or drive, caught in gravitic or electric potential wells, or clouding lagrange points. Phototrophs are categorised as such when gathering most of their energy from the sun, even if engaging in some predation on other organisms.

Other sources, etheric or plainly odd, feed xenotrophs. By far the most common, though rare enough still, are those that plunder magnetic turbulences. Electrochemical 'ferns', cyberglinidae worms and tiny-shelled fluxoyster have populations preserved in parks around some of the major massdrivers through the system, while more exotic breeds unfurl in the umbrella of Jupiter's magnetosphere.

Many species of xenotroph are wrapped in mystery and mystique. The neutronic 'pearl' of the blackbox clam is claimed to detect ghosts. The 'antenna-eyes' of urban myth (in truth, deepspace cryptographs use not human brains but only optic nerves, from raptors, owls, even mantis shrimp). Caution should be used when registering new lifeforms as xenotrophs. An organism simply not making genetic sense, or being built from a different clade of atoms entirely, does not qualify it as a xenotroph if it is more properly carnivorous, etc.

Stowaways such as this skipjack mussel are considered
pests by shipping companies and delicacies by sailors.

Organisms are secondarily categorised as a function of their environment.

Cataclysmic waves of heat and pressure wash from the prow of a body entering an atmosphere. Even when the apocalyptic forces of reentry are not enough to kill an organism, exposure to the weight and erosion of a world often finish the job. Despite these ferocious hurdles - and sometimes because of them - some life thrives on the rhythm of reentry. Most species of space barnacle are utterly unperturbed by fire and brimstone, and appreciate the burst of fresh gases gleaned from new air. Many species have adapted to suit very tight niches; the regular schedule of certain inter-moon couriers, the atmosphere-skimming flights of Jovian weather balloons. 

Most dedicated reentrant organisms require some consistency from their environment. All recorded species of glass eel require a reentry event soon after spawning, while tiny elvers can shrug off staggering decelerations and heat blooms, and before they're eaten by their parents. There are some creatures - roaches, diamond-backed crabs, screwdriver snails and "star hogs" (more properly macrotardigradum) - that are not considered true reentrants, having no particular taste for sonic booms and pesky gravity, but will nevertheless survive an event, and thrive in the space and resource left behind by one.

In more permanently spacefaring climates, diurnal environments are, narrowly, the most densely populated. With permanent exposure to the sun (or another powerful source of radiation), the challenge in these environments is not obtaining energy, but releasing it. Cold-blooded arthropods sabotage the efficiency of their own bodies, locking excess heat in chemical effluent. Fungal friar's cap grows only on the edge of light, mycelium crawling back into shadow to bleed heat. Many diurnal phototrophs express extreme tropism, contorting white belly to the sun and turning black back on the void. 

The rich wash of energy allows for an explosion of phototrophic life, and in a small pastoral irony one of the great boons of this life is its shadow. Tiny helmeted jesterfish will only leave their host plant in bursts of a few hot seconds. Miasmic morays, ever the bane of propulsion mechanics, expose only their sensitive nose to the heat of sol. And of course that most enduring, taxonomically elusive clade, the manifold forms of life that lurk about spilled reactors, soaking in what bare minimum of high-energy radiation will let them survive, enduring the genetic rebellion caused by this disappetising diet.

A surfeit of chemotrophs, in particular, excel in nocturnal environments with sufficient other sources of food. The seething soup of reactive chemistry that pours out of drives and waste vents, especially on larger ships, holds uncounted microbes: bacteria, algae and nematodes; sizzling stains of RNA and simple rogue enzymes. A whole host of secondary feeders filters this life, from flatworms and hydras, anemones and jellies, to jet-propelled jackboot clams. 

While many species of crab love to sunbathe, they gorge contendely in dark, dense pits protected from solar rays. Even diurnal organisms may need some somnolent shade, and animals such as the greenback spider prey almost exclusively on light-loving creatures that slip into the darkness to rest or nest. Very few nocturnal organisms leave their environment willingly, and though several diurnal species lay their eggs in the protection of perpetual night, most nocturnal embryos would be destroyed if exposed to the light.

The classification crepuscular is reserved specifically for environments with a light cycle, most commonly ship or substrate spinning with respect to the sun. The definition wanders, however. This 'environment' may well be another larger organism, from sky coral to massed lichens to the perennially hibernating floatoad. Habitats may be orbited by lights, periodically submersed by a reflecting moon, or lit by yet more inscrutable means. 

The exceedingly rare xenotroph "Euclides' stone" grows only in tidally locked night, feeding from a wheeling zodiac of neutron stars. It is important to note that faster spinning substrates have a more dispersed atmosphere, increasing livable altitude of atmosphere in strongly dielectric and/or polar environments, while usually reducing it when particulates are primarily held by gravity. These properties are just one reason why lichens and ship-side corals carry so much information about the history of a vessel.

Closeup of a styro-core hull shows colonisation by dark blue gloeophoria in sections of a lichenous growth that have been repeatedly electrocuted by reactor hitch

There is still contention over when an organism itself may blur these definitions. Across all environments are recorded so called obligatory nomads, which must travel continuously across their little world, seeking darkness or light or the perfect balance of both. In this text we will categorise creatures according to the environments they make for themselves. New moon mantis shrimp, ever scrabbling into darkness, are considered nocturnal. Feedstock shrimp, though they must escape the sun's disapproving glare to perform the intricate bioluminescent dance of their mating, are ultimately considered diurnal.

Many organisms require additional, sometimes extremely precise conditions to thrive. Compositions of atmosphere, water, gravity, charge and magnetism are painted in portmanteau throughout the solar system. The next chapters of this work will cover all of these environments in greater detail, with an additional chapter dedicated to some of the pioneer lifeforms that construct their own ecologies, from the complex mutualisms of a shipwright 'mite hive to the soap bubble-world cupped in the body of a solar jelly.