(Alder & Hancock, 1848)
Atlantic coast of Europe, and NE Nth America
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.
• 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.
Rudman, W.B., 2003 (July 18) Eubranchus exiguus (Alder & Hancock, 1848). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/eubrexig
July 22, 2003
From: Alan Shepard
I've attached a couple of photos of what I believe is Eubranchus exiguus. The photos were taken at Folly Cove in Gloucester, Massachusetts, USA.
The first photo [upper right, lower left] with the pair on a hydroid was taken in approximately 10m of water. These were tiny individuals, no more than 5mm long. Water temperature was approximately 6c.
The second photo [lower right] is of a larger individual, nearly 10mm long. It was taken in shallower water, maybe 5m. In this photo you can make out some of the internal structure of the sea slug.
Tolland, CT, USA
With the proviso inherent in Bernard Picton's message I would agree that this is most probably Eubranchus exiguus.
June 7, 2002
From: Bernard Picton
UPPER: Skomer Is, Pembrokeshire, South Wales - Jun 1991 - 8mm
LOWER: Mulroy Bay, Co. Donegal, Ireland - April 1978 - 8mm
email@example.comPicton, B. , 2002 (Jun 7) Eubranchus exiguus from Europe. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7153
May 27, 2002
From: Jim Anderson
Dear Dr. Rudman,
Here is a photo of Eubranchus exiguus from a recent trip. It was identified by Bernard Picton as a juvenile. It was photographed in a tupperware box after bringing it off Smyth Rock at 18 metres in Loch Nevis on the west coast of Scotland on 21 April this year. It was approx 3mm long.
firstname.lastname@example.orgAnderson, J., 2002 (May 27) Eubranchus exiguus from Scotland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7026
April 21, 2002
From: Alan Shepard
I sent my photo of what you tentatively thought was Eubranchus exiguus to Dr. Larry Harris at the University of New Hampshire and he concurred that it was E. exiguus. He stated that they would be quite numerous this time of year and that I might wish to search areas around pier pilings and the like for more.
email@example.comShepard, A., 2002 (Apr 21) Regarding Eubranchus exiguus. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6783
Why I suggested some more photos would be interesting, is that as far as I can see in the literature, E. exiguus usually had distinctive brown spots on the body and the cerata, which I can't see in your photo. Knowing that there seems to still be some confusion about just how many species of Eubranchus there are in Europe, It is possible that your animal might be something else. Any information on colour variation and egg ribbon could therefore be of interest to anyone trying to sort out the identity of these animals in the future.
April 8, 2002
From: Alan Shepard
I really need help on the ID of this nudibranch. I took the photo on February 24, 2002 at Folly Cove in Gloucester, Massachusetts, USA in approximately 20 feet of water. The nudibranch is about 5 mm long.
I have never encountered this one before and I was particularly taken by the light blue tips to the cerata. I tried looking through Bleakney's book but it's not helping or I'm missing something.
firstname.lastname@example.orgShepard, A., 2002 (Apr 8) Eubranchus? from Massachusetts. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6658
I am pretty sure this is a species of Eubranchus, perhaps E. exiguus, but this group are quite difficult to identify to species without local knowledge. Hopefully someone with a knowledge of the North Atlantic fauna will recognise it