Sedentaria is a diverse
clade of
annelid worms. It is traditionally treated as a subclass of the paraphyletic class
Polychaeta
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ...
, but it is also a
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...
group uniting several
polychaete
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ...
s and the monophyletic class
Clitellata
The Clitellata are a class of annelid worms, characterized by having a clitellum - the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, t ...
. It is the sister group of
Errantia.
Phylogeny
The phylogeny of
polychaete
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ...
s 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.
Other groups that are nested within Sedentaria are:
Clitellata
The Clitellata are a class of annelid worms, characterized by having a clitellum - the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, t ...
, the
Sabellida/
Spionida
Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones.
Characteristics
Spionids have a single pair of flexible feeding tentac ...
clade,
Opheliida,
Echiura
The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily lo ...
,
Cirratuliformia,
Terebelliformia,
Maldanomorpha and the families
Siboglinidae and
Capitellidae.
Some
taxa
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
, such as
Spintheridae and
Myzostomida
The Myzostomida or Myzostomatida are an order of small marine worms, which are parasitic on echinoderms, mostly crinoids. These highly unusual and diverse annelids were first discovered by Friedrich Sigismund Leuckart in 1827.
Morphology
A ...
, are still difficult to place due to their long branching, but they likely belong to either
Errantia or Sedentaria.
References
{{taxonbar, from=Q9373141
Polychaetes
Annelids