Cossura a small group of polychaetes that inhabit all different depths from the ocean (Zhadan et. al 2012). It only includes one genus with two synonymized genera but that one genus cossura has 23 species (Zhadan et. al 2012). They are unique polychaetes because they have unpaired branchial filament and a weird feeding appartus where their eversible mouth tentacles are attached outside of the buccal cavity (Tzetlin 2012). The body wall in cossura is made of 5 longitudianl muscles which have two dorsal, two ventral, and one ventromedial (Zhadan et. al 2014). Four lingitudinal bands go to the middle of the prostomium and 5-14 paired dorsoventral fibers tale place in its spot (Zhadan et. al 2014). And each muscle contains one thick and two think longitudinal muscle filaments (Zhadan et. at 2014). Finally, the brancial filament contains two longitudinal muscles that do not connect with the body musculature (Khadan 2012)
Cossura are a small group of polychaetes that live in all different depths, it includes one species with 23 species (Zhadan 2012). They are unique compared to other polychaetes because they have an unpaired branchial filament and a peculiar way to feed; their mouth tentacles are on the outside of their buccal caity (Zhadan 2012). Their body wall is made of 5 longitudinal bands with two dorsal, two ventral, and one ventromedial (Zhadan 2014). They have four longitudinal bands that go to the middle of the prostium and 5-14 dorso-ventral muscle fibres (Zhadan 2014). The branchial filament has two longitudinal muscle fibres that don't connect with the body musculature (Zhadan 2014).
