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/find/eubrexig

Related messages


Eubranchus exiguus from Massachusetts, USA

July 22, 2003
From: Alan Shepard

Bill -
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.
Alan Shepard
Tolland, CT, USA

alan.chepard@snet.net

Dear Alan,
With the proviso inherent in Bernard Picton's message I would agree that this is most probably Eubranchus exiguus.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Jul 22). Comment on Eubranchus exiguus from Massachusetts, USA by Alan Shepard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10463

Eubranchus exiguus from Europe

June 7, 2002
From: Bernard Picton


Dear Bill,
To accompany my message on Eubranchus, here are some pictures of Eubranchus exiguus from the British Isles

UPPER: Skomer Is, Pembrokeshire, South Wales - Jun 1991 - 8mm
LOWER: Mulroy Bay, Co. Donegal, Ireland - April 1978 - 8mm

Bernard

bernard.picton.um@nics.gov.uk

Picton, B. , 2002 (Jun 7) Eubranchus exiguus from Europe. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7153

Thanks Bernard,
Bill Rudman


Eubranchus exiguus from Scotland

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.

Jim Anderson

jander4454@aol.com

Anderson, J., 2002 (May 27) Eubranchus exiguus from Scotland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7026

Thanks Jim,
Bill Rudman


Regarding Eubranchus exiguus

April 21, 2002
From: Alan Shepard

Bill-
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.
Thanks,
Alan Shepard

alan.chepard@snet.net

Shepard, A., 2002 (Apr 21) Regarding Eubranchus exiguus. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6783

Dear Alan,
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.
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Apr 21). Comment on Regarding Eubranchus exiguus by Alan Shepard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6783

Eubranchus? from Massachusetts

April 8, 2002
From: Alan Shepard

Bill -
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.

Thanks,
Alan Shepard

alan.shepard@po.state.ct.us

Shepard, A., 2002 (Apr 8) Eubranchus? from Massachusetts. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6658

Dear Alan,
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
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Apr 8). Comment on Eubranchus? from Massachusetts by Alan Shepard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6658