Onchnesoma steenstrupii steenstrupii (Koren and Danielssen, 1875)

A cosmopolitan species often found in mollusk shells and polychaete tubes

Distinguishing characteristics
Spherical or pear-shaped, trunk with thin introvert, five to ten times the trunk length
Tentacles not present; instead there is a flat, circular oral disk

Size
Common trunk length: 0.5-5.0 mm long and 0.3-2.0 mm wide

Color
Grey, yellow, orange, rusty red

Habitat
Inhabits sand and mud in cool to cold bathyal waters

Feeding
Unknown

Life cycle
Unknown

Distribution
Common In the northern Atlantic Ocean, present in the southeastern Atlantic, higher latitudes of the western Pacific and the southwestern Indian Ocean.

References

• Cutler EB (1965) Sipunculids of Madagascar. Extrait des Cahiers ORSTOM. Oceanographie 3:51-63
• Cutler EB (1973) Sipuncula of the western north Atlantic. Bulletin of the American Museum of Natural History 152:103-204
• Cutler EB (1994) The Sipuncula. Their Systematics, Biology, and Evolution. 1-453
• Fischer W (1922) Gephyreen des Reichsmuseums zu Stockholm. Archiv für Zoologi 14:1-39
• Fischer W (1929) Die Sipunculiden, Priapuliden und Echiuren der Arktis. 5
• Gibbs PE (2001) Sipunculans. Key and Notes for the Identification of British Species, Synopses of the British Fauna (New Series). Crothers J.H.// Hayward P.J.
• Gibbs PE, Cutler EB (1987) A classification of phylum Sipuncula. Bulletin of the British Museum Natural History Zoology 52:43-58
• Murina GV (1977) Marine worms of the Arctic and boreal waters of Europe. Identification books of the USSR fauna
• Murina GV, Sorensen J (2004) Marine Worms of the Phylum Sipuncula in Faroese waters. Fr?dskaparrit 51:280-291
• Pancucci-Papadopoulou MA, Murina GV, Zenetos A (1999) The phylum Sipuncula in the Mediteranean Sea. 1-109
• Wesenberg-Lund E (1930) Priapulida and Sipunculidae. Danish Ingolf-Expedition 4:1-44
• Wesenberg-Lund E (1938) Norwegian Gephyrea from the collections of the Zoological Museum of Trondheim. Det Kongelige Norske Videnskabers Selskabs Forhandlinger 11:26-29
• Wesenberg-Lund E (1939) Gephyreans from Swedish waters in the Museum of Natural History of Gothenburg. Göteborgs Kungliga Vetenskaps Vittenhets-Samhälles Handlingar 6:1-35
• Wesenberg-Lund E (1938) Norwegian Gephyrea from the collections of the Zoological Museum of Trondheim. Det Kongelige Norske Videnskabers Selskabs Forhandlinger 11:26-29
• Wesenberg-Lund E (1939) Gephyreans from Swedish waters in the Museum of Natural History of Gothenburg. Göteborgs Kungliga Vetenskaps Vittenhets-Samhauml;lles Handlingar 6:1-35