Eubranchus exiguus
(Alder & Hancock, 1848)

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Eubranchidae

DISTRIBUTION

Atlantic coast of Europe, and NE Nth America

PHOTO

Mulroy Bay, Co. Donegal, Ireland - April 1978 - 8mm. Photo: B.E.Picton

The body is translucent grey or yellowish white, with speckles and larger blotches of brown or olive green. There are no large areas of opaque white pigment on the dorsum or the sides of the body. The cerata are relatively few in number and have a large subterminal swelling. The ceratal wall is transparent with scattered spots of the same colour as on the body wall . Ther can be traces of 2-3 white or light-coloured vague rings. The tip of each ceras usually bears a ring of chalk-white pigment which obscures the cnidosac within; there is usually a small band of brown apical to this. The the ceratal digestive gland ducts are pale brown. The tentacles have a subterminal white band followed by 1-2 subterminal bands of brown.

Thompson (1988) reports that it feeds on a variety of calyptoblastic hydroids, but Bernard Picton suggests that it feeds only on Obelia longissima or Obelia dichotoma. It is tolerant od low salinities (down to 5-7 ppt in the Netherlands) and has been recorded from scattered shallow sublittoral localities all around the British Isles as well as from the White Sea, Massachusetts, Connecticut, Norway, the Baltic, Atlantic and Mediterranean coasts of France, Italy to 140 m. Normally grows to approximately 10 mm in length, but has been reported to reach 18 mm on rare occasions. Edmunds & Kress (1969) report that the spawn is reniform and laid in clusters along the stems of hydroids.

See Bernard Picton's message on Eubranchus spp in North Atlantic.

References:
• Alder, J & Hancock, A. (1848). Additions to the British species of nudibranchiate Mollusca. Annals and Magazine of Natural History, 1(2): 189-192
• Edmunds, M. & Kress, A. (1969) On the European species of Eubranchus (Mollusca Opisthobranchia). Journal of the Marine Biological Association, United Kingdom, 49(4): 879-912, Pls.1-2.
• Schmeckel, L. & Portmann, A. (1982). Opisthobranchia des Mittelmeeres.
• Thompson,T.E. (1988). Molluscs: Benthic Opisthobranchs. The Linnean Society of London and the Estuarine and Brackish-Water Sciences Association.

Authorship details
Rudman, W.B., 2003 (July 18) Eubranchus exiguus (Alder & Hancock, 1848). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/eubrexig

Copyright © Australian Museum, 1998-2010