Sedentaria

Sedentaria are mainly found within marine environments that have low oxygen levels and are specially adapted to these low oxygen environments by increasing gill surface area and having high-affinity respiratory proteins. Furthermore, they go through a process of metabolic depression which lowers their energy use so that they can inhabit these low oxygen zones.

Etymology

The name Sedentaria - to sit or remain in place - describes the habits of this group of worms, contrasted to its sister group, "Errantia" - meaning to wander. Thus, Sedentaria worms are known for staying in a certain vicinity: this includes tube-dwellers (see, Riftia), or burrowers, such as earthworms, who tend to stay localized in their tunnels. By contrast, Errantia roam more freely.