Hesionidae

Hesionidae are a family of phyllodocid bristle worms. They are marine organisms. Most are found on the continental shelf; Hesiocaeca methanicola is found on methane ice, where it feeds on bacterial biofilms.
A characteristic apomorphy of the Hesionidae are the cirrophores of the anterior segments, which are well-developed cup-like sheaths; the cirri of the subsequent segments insert into the parapodia directly, or with just a vestigial cirrophore.

Systematics

As phyllodocids, the Hesionidae belong to the order Aciculata, one of the three main clades of polychaetes. They appear to be part of the basal radiation of the main lineage of phyllodocids, alongside such families as the ragworms, the Pilargidae and Sphaerodoridae which are closely related to each other, the very ancient Syllidae, and perhaps the more advanced catworms.
Numerous genera are still treated as Hesionidae incertae sedis, not reliably assignable to either of the three generally recognized hesionid subfamilies:Alikuhnia Anoplonereis Giard, 1882Cirrosyllis Schmarda, 1861Elisesione Salazar-Vallejo, 2016FriedericiellaHesiodeira Blake & Hilbig, 1990Hesiolyra Blake, 1985 Hesionella Hartman, 1939Heteropodarke Pleijel, 1999Leocratides Ehlers, 1908Mahesia Westheide, 2000Neopodarke Hartman, 1965Orseis Ehlers, 1864Oxydromus Grube, 1855Parahesione Pettibone, 1956Parapodarke Czerniavsky, 1882Periboea Ehlers, 1864Podarke Ehlers, 1864Pseudosyllidia Czerniavsky, 1882Sinohesione Westheide, Purschke & Mangerich, 1994Sirsoe Pleijel, 1998Struwela Hartmann-Schröder, 1959