Tethys fimbria
Linnaeus, 1767

Family: Tethydidae


Mediterranean and east Atlantic coast from Portugal to the Gulf of Guinea.


Antalya, Turkey, Divesite: Kiris, Depth: 14m, June 2002. Size: 25cm. Photo: Adnan Buyuk [ado2000tr@yahoo.com].

Tethys fimbria is the sole species of the genus Tethys. Species of Tethys, and the closely related genus Melibe, have a large oral hood, used in the capture of food, and a set of prominent cerata down each side of the body. In Tethys the cerata are smooth, with a pair of small basal gills, while in Melibe the cerata are usually papillate or tuberculate, and there are no basal gills. Like all members of the family they lack a radula. Internally, Tethys has no stomach plates, the posterior digestive gland forms a solid mass, surrounded by the gonad, while in Melibe there are a ring of stomach plates, the digestive gland is usually diffuse, branching or broken up some way, and the gonad lies in masses beneath the digestive gland.

Tethys fimbria can grow to 30cm, and the large oral hood is fringed with sensitive papillae. The rhinophores are small, mainly hidden in the expanded collar of the sheath that surrounds each one. The large flattened cerata are easily autotomised. The animal is a translucent white except for the blackish brown spots on the cerata, and sometimes on the edge of the oral hood and the foot. Locally common on soft sandy-mud from 20 to 150 meters, where they feed on small crustacea. It is reported to swim well.

Compare this species with others, such as Euselenops, which have adapted for a life in soft sediments.

• Cattaneo-Vietti, R., Chemello, R., Giannuzzi-Savelli, R. (1990) Atlas of Mediterranean Nudibranchs. La Conchiglia, Rome. 264 pages.
• Odhner, N.H. (1936) Nudibranchia Dendronotacea - A revision of the system. Memoires du Musee Royal d'Histoire Naturelle de Belgique, series 2, fasc. 3: 1057-1128. (Pl. 1)
• Schmekel, L. & Portmann, A., 1982. Opisthobranchia des Mittelmeeres. Nudibranchia und Saccoglossa.

Authorship details
Rudman, W.B., 2002 (October 14) Tethys fimbria Linnaeus, 1767. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/tethfimb

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