A phylum of animals from Old Earth, originally with about 17,000 species. Examples are earthworms, ragworms, fanworms, and leeches. Annelids are long soft wormlike animals, typically composed of a number of similar segments, and lacking any internal or external skeleton, and the original species ranged in size from microscopic individuals less than a millimetre long to animals as large as 3 metres in length. They were native to moist or aquatic environments ranging from damp earth to streams and ponds to marine intertidal, pelagic, and even hydrothermal environments. Most commonly burrow in sediment and feed on detritus, but some are sessile filter-feeders, predators or herbivores in the water column, or internal or external parasites.
The original species and their various descendants are important elements in the ecologies of habs and terraformed worlds. Genes from annelid species native to hydrothermal vents have been incorporated into a number of high-temperature tweaks, human and otherwise. Annelid provolves are relatively rare, but a well-known example is Clade Eudore.