Sedentaria

Sedentaria
	Examples of Sedentaria (clockwise from upper left corner): Sabellida, Echiura, Maldanomorpha, Clitellata, Terebelliformia, Siboglinidae.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Annelida
Clade:	Pleistoannelida
Clade:	Sedentaria; Lamarck 1818
Orders and families
	Orbiniida; Cirratuliformia; Siboglinidae (=Pogonophora); Sabellida; Spionida; Opheliida; Capitellida Echiura; Capitellidae; ; Terebelliformia; Maldanomorpha; Clitellata "Oligochaetes"; Hirudinea; ; Incertae sedis ?Myzostomida; ?Spintheridae;

Sedentaria is a diverse clade of annelid worms. It is traditionally treated as a subclass of the paraphyletic class Polychaeta, but it is also a monophyletic group uniting several polychaetes and the monophyletic class Clitellata. It is the sister group of Errantia.

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 inhibit these low oxygen zones .