Eubranchus doriae – a sea slug
Eubranchus doriae (Trinchese, 1874)
Family:
This cryptic sea slug is rare in Northern Ireland, and possibly under-recorded, being only found off the north coast.
In brief
- This species is rare in Northern Ireland, being found only off the north coast
- Northern Ireland is the UK stronghold for this species
- It can only be seen by diving
- Threats to this species are unknown, as there is little knowledge of the current populations in Britain and Ireland.
Species description
This is a small nudibranch sea slug, with adults only growing to about 12mm. The body is translucent white, with scattered brown or green pigment on the back and cerata. The cerata have two to three rows of tubercles giving an irregular knobbly appearance. The tip of each ceras is covered by a pale patch, and encircled by a brown-coloured ring. The rhinophoral and oral tentacles are smooth; the tips of these tentacles are white with a subterminal brown band.
Life cycle
As with all nudibranch sea slugs, Eubranchus doriae is a hermaphrodite. The spawn is a flared cup-like circle of white ribbon with a basal pad attaching it to the stem of its hydroid prey. Spawning normally takes place in November.
Similar species
There are two similar species: Eubranchus exiguus and E. vittatus. Eubranchus doriae may be easily distinguished from E. vittatus by the presence of tubercles on the cerata. Eubranchus exiguus has few cerata, which are urn-shaped, and is usually found on Obelia sp. attached to kelp.
How to see this species
This species has only been found off the Skerries (near Portrush) and Fair Head in Northern Ireland, in depths of 18-31m between 1982 and 1985 in July and August. It lives on mixed substrates of bedrock, boulders and pebbles. It is carnivorous, feeding on the plumularian hydroid Kirchenpaueria similis.
Current status
This species has not been seen in Northern Ireland since 1985. It is rare in Northern Ireland, being only found at the Skerries and Fair Head. It has been located elsewhere in the Republic of Ireland from Mulroy Bay, County Donegal south down the west coast, to Lough Hyne, County Cork. It also occurs on the south and western coasts of Britain, although it has been found as far north as St. Kilda, and elsewhere the Atlantic coast of France and the Mediterranean. It is probably under-recorded.
Why is this species a priority in Northern Ireland?
- This species is rare with Northern Ireland being the UK stronghold for this species.
Threats/Causes of decline
Threats to this species are unknown, as there is little knowledge of the current populations in Britain and Ireland.
Conservation of this species
Current action
- None known
Proposed objectives/actions
- Perform targeted surveys to ascertain the current status of the species in Northern Ireland
- If refound, ensure that the population is maintained.
What you can do
Records of new sites and sizes of populations are always valuable. Send to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU. Tel: 028 9039 5257, cedar.info [at] nmni.com. If you are a diver, and interested in becoming involved in recording marine life in Northern Ireland through the Seasearch project, contact Claire Goodwin at claire.goodwin [at] gmail.com or look at the web site www.seasearch.org.uk (Northern Ireland web pages).
Further information
Links
Encyclopedia of Marine Life
Marine Nature Conservation Review Database
Literature
Picton, B.E. and Morrow, C.C. (1994). A Field Guide to the Nudibranchs of the British Isles. Immel Publishing, London.
Seaward, D.R. (1982). Sea Area Atlas of the Marine Molluscs of Britain and Ireland, 53pp. + 746 figures. Nature Conservancy Council, Peterborough for Conchological Society of Great Britain & Ireland.
Seaward, D.R. (1990). Distribution of the marine molluscs of north west Europe 114pp. Nature Conservancy Council, Peterborough for Conchological Society of Great Britain & Ireland.
Thompson, T.E. (1988). Molluscs: benthic opisthobranchs. Synopses of the British Fauna (new series) no. 8 (second edition). The Linnean Society of London and The Estuarine & Brackish-water Sciences Association.
Thompson, T.E. and Brown, G.H. (1984). Biology of opisthobranch molluscs. Volume II. The Ray Society, London.
Text written by:
Dr Julia Nunn, Environmental Recorder, CEDaR, Ulster Museum
iNaturalist: Species account : iNaturalist World Species Observations database