Sedentaria | |
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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 |
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]
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]
The phylogeny of polychaetes is slowly being resolved. Sedentaria and Errantia are the two biggest clades of polychaetes, and together they compose clade Pleistoannelida. Sedentaria's most basal clade is Orbiniida. [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]
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]