Autotrophic planktonic organisms that are the primary producers within their ecology, usually via photosynthesis. Most often they are of microscopic size and can be detected only by the colour they give to the water (or more rarely, the air) they float in, though some artificial or xenobiont examples may be centimetres, metres, or even kilometres in extent. Typical phytoplankton of Old Earth, common to standard Terragen-derived biomes of large habs or terraformed worlds, are single-celled algae; microscopic protist eukaryotes such as dinoflagellates, diatoms, or coccolithophores, or even smaller prokaryotic cells such as cyanobacteria. There are of course many xenobiont, gengineered, or lazurogened equivalents.
- Zooplankton - Text by M. Alan Kazlev
Animals that float passively in the water as part of the plankton. Zooplankton feed on other plankton (phytoplankton, bacterioplankton or other zooplankton) and are in turn food for larger aquatic organisms. An important part of the aquatic ecology of any terragen and terragen-type ecosystem.