Bacterial Flora

These macroareonts, which have been christened Pocupoa, have only recently been discovered around temperate mountain streams leading from Hadriacus Mons into the Hellas Basin. They are perhaps among the most wonderful creatures, for they are multicellular, centimetre-tall prokaryotic organisms. Multicellular prokaryotes do exist on Earth as well, in the form of myxobacteria and some blue-green algae, but none have ever been observed growing to this scale. Pocupoa are characterized by having a rigid and porous outer shell and either an internal layer or spicule skeleton, all made from silicon dioxide, similar to diatoms. Most of the body is made up of this skeleton or hollow, water-filled spaces, with the actual living cells only making up a small amount of the volume. How exactly these organisms work is still being debated. On Earth, multicellularity in prokaryotes is usually associated with harsh living conditions and nitrogen starvation. When lacking enough nitrogen, cyanobacteria-filaments will form special cells called heterocysts which do not participate in photosynthesis but are instead surrounded by the other cells of the body to create anaerobic conditions under which the heterocyst can better fix nitrogen from the air or water. On Mars, nitrogen makes up only 3% of the atmosphere, so such organisms would be under a constant state of nitrogen starvation. It seems very likely then that these primitive cells have become permanently multicellular to combat these conditions through teamwork. The siliceous shell structure has likely evolved to both help separating photosynthesizers from nitrogen-fixers, as well as creating anoxic conditions inside the body for the nitrogen-fixers. In addition to these two cell-types, there also seem to be cells dedicated towards building and holding together the structure. Despite this specialization into different cell-types, Pocupoa do not possess genuine tissues, as every cell seems to be capable of morphing into a different type when the need arises, a condition that can also be seen in sponges.

Several types of Pocupoa have been identified, though we do not know if these are genuinely different families or simply a variety of morphs the colonies can assume. The most common type are the Durupoa, which have a tube-like build. In the Acupoa, the tip instead consists of an ornate cap resembling the Kremlin-towers. In the Sporopoa, the cap is formed into a mushroom-like hood, potentially to protect the soft fruiting-bodies underneath. In the Scutrapoa the hood seems to be inverted into a bowl, for reasons unknown. Sporopoa interestingly seem to be the only members who reproduce through wind-carried propagules. Most other types instead seem to go for a stolon-based reproduction, as their bases form long-winding, thin roots both above and underground that interestingly connect both with conspecifics and other types of Pocupoa. While all of these organisms likely reproduce asexually, it is not unthinkable that horizontal gene-exchange between individuals might occur through these networks.

Some role of the Pocupoa in the Sulphur-Cycle is also suspected, though what role is uncertain. The assumption stems from close association of these organisms with Cochleophyta, which are corkscrew-shaped plants and among the most primitive of the Arephyta, as they lack symbiosis with sulphur-reducers and therefore require free hydrogen sulfide in the environment.

Direct interactions between animals and Pocupoa have not been observed so far. Most seem to either ignore them or in some cases even avoid them.