Sedentaria
Subclass of annelid worms
From Wikipedia, the free encyclopedia
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.[1]
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| Sedentaria | |
|---|---|
| Examples of Sedentaria (clockwise from upper left corner): Sabellida, Echiura, Maldanomorpha, Clitellata, Terebelliformia, Siboglinidae. | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Clade: | Sedentaria Lamarck 1818 |
| Orders and families | |
Incertae sedis | |
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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.[2]
Phylogeny
The phylogeny of polychaetes is slowly being resolved. Sedentaria and Errantia are the two biggest clades of polychaetes, and together they compose clade Pleistoannelida. The Orbiniida are sister to all other Sedentaria lineages.[3] Other groups that are nested within Sedentaria are: Clitellata, the Sabellida/Spionida clade, Opheliida, Echiura, Cirratuliformia, Terebelliformia, Maldanomorpha and the families Siboglinidae and Capitellidae.[4][1][5]
| Pleistoannelida |
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Some taxa, such as Spintheridae and Myzostomida, are still difficult to place due to their long branching, but they likely belong to either Errantia or Sedentaria.[1]