The Bottom of the Food-Chain
So let’s start at the beginning. You want to populate the living world? It starts with energy. Usually that energy comes from the sun, so the first issue I should tackle in designing an alien ecosystem should be harvesting sunlight.
Terran plants capture sunlight primarily with chlorophyll (there are a few other pigments that help out such as melanin, anthocyanin, and various carotenoids) which collects the energy necessary to drive the proton pumps that turn water and co2 into oxygen and glucose sugar. Sugar can then be oxidized to produce CO2 and energy when needed. an estimable process and one we’ll probably see evolve independently elsewhere, but are there alternatives?
Steel-wool trees
Rather than carry out photosynthesis through living tissue, steel-wool trees extrude filaments of laden with arsenite, which oxidizes under sunlight to produce arsenate and carbon monoxide. Since this biome produces no oxygen (and indeed, oxygen is toxic to most of its inhabitants), it is violently incompatible with all surrounding biomes. It is theorized that this form of life was uncommon on the Steel-wool home-world when it was linked to Junction (~100 MYA), but became dominant after a later planetary catastrophe. The presence of more familiar photosynthesizers on the edges of the steel-wool zone support this hypothesis.
Kelp Trees
Kelp trees use methane and water to produce glucose and hydrogen, which they store in gas bladders to provide buoyancy in the air. As with the steel-wool trees, this form of metabolism is probably a relatively recent development, possibly in response to a global release of methane hydrate in the kelp-tree home-world’s past. The kelp tree zone now maintains an active methane cycle, which operates alongside an Earthlike carbon-dioxide-oxygen cycle. The need for methane puts kelp trees at a disadvantage that is only somewhat offset by the extremely efficient dispersal of their hydrogen balloon-seeds.
Kelp tree forests are common at high altitudes, along mountain ridges. How these colonies established a working methane cycle so far from their home wormhole is unknown. Native superstitions regarding tool-using aliens are entirely unsubstantiated.
Kinetotrophs
Kinetosynthetic “clappers” use motion to build up charge in piezoelectric crystals deposited in a hinge or bearing between the clapper’s vanes and its holdfast. This energy is used to ionize hydrogen to form a proton gradient and synthesize chemical energy-storage, similar to ATP synthesis in Terran organisms. The source of the motion may be the omnipresent wind currents of their tidally-locked home-world, or from the action of symbiotic animal life.
Even boring old photosynthesis can look very weird if you do it right. Consider, for example, the unmoving light-source of the tidally-locked home-world of the clappers.
Spangletrees
Like the clappers to which they are distantly related, spangletrees’ principle structure chemical is polyester. This material can be spun into structures of many forms, ranging from hard and waxy near the roots to the flexible, selectively transparent filaments that grow from the crown in place of leaves. Some of these filaments simply pipe sunlight into photosynthetic nodules at their base, but others redirect sunlight to clone spangletrees that bud of the roots of the parent.
This adaptation originally evolved to gain competitive access to a single unmoving source of light and energy on a tidally-locked world. A single colonial forest can feed sunlight to its colonies across the day/night terminator in exchange for nutrients. Even at the antestellar point (or “Night Pole”) of the planet, sunlight imported from the day side provides enough energy to drive photosynthesis. Spangletree filaments can also be grown to shade competitors or, focus sunlight and burn them.
Diatoms
Rather than stretching around an expanding skeleton of dead wood like Terran trees, diatom-zone plants excrete a “test” of transparent silicate plates held together by flexible silicone. For ground-covering “tureen grass” the test is flat and grows outward until its edge hits the edge of another tureen plate. Growing en masse, tureen forms an array of hexagons of various width (depending on the underlying ground). When a plate matures, it sporulates, converting all of its tissues into bead-shaped reproductive packets and removing silicone from its test, making it brittle. Animals can now smash the test to drink the nutrient soup inside, thereby spreading the spores. Other animals smash healthy plates (usually by disgorging sulfuric acid onto them first to dissolve the silicone component of their tests) and can be regarded as herbivores or parasites.
Under the soil, more symbiosis is going on with another species of sponge that creates glassy tubes that transport water and mineral salts in exchange for sugars manufactured by the plates. While the plates usually sporulate and die within a year, the aqueducts live much longer.
Treelike diatoms grow by extruding a glassy spire, around which a thin ribbon of water-filled photosynthetic chambers winds like the thread on a screw.
And no speculative biology would be complete without plant-animals…
Worm Trees
Diploid, sessile ‘trees’ produce monoploid, mobile “worms” (more properly “zoophytes”). In many species, zoophyte stage can reproduce parenthetically. Parthenogenic clones may remain in colonial swarms or split up, and take up many of the roles filled by Terran arthropods and annelids. Zoophytes swap genetic material through intercourse, which expressed when they germinate into diploid trees. Commonly, swarms of clones gather to create a many-branched or thicket-like diploid form. In one lineage, a fraction of the swarm does not germinate, and take on specialized roles to protect, gather nutrients for, or weed around their sibling tree.
Neotonous, permanent zoophytes never become sessile, but instead grow photosynthetic flaps as zoophytes.
