(Alder & Hancock, 1854)
Eastern Atlantic from Isle of Man, and Northern Ireland, France, western Mediterranean and Morocco. Also recorded below from the Netherlands.
Zierikzee (Zeelandbrug), de Oosterschelde, the Netherlands. PHOTO: Peter van Bragt.
Grows to about 26mm. Thought (Thompson & Brown, 1984) to feed on species of the bryozoan, Bugula, but Bernard Picton's message suggests they live and feed on Scrupocellaria.
• Thompson, T.E. & Brown, G.H. (1984) Biology of Opisthobranch Molluscs, Vol 2. Ray Society: London.
See Janolus cf. hyalinus for discussion on the identity of a species from Australia and New Zealand considered to be J. hyalinus.Authorship details
Rudman, W.B., 1999 (August 29) Janolus hyalinus (Alder & Hancock, 1854). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/janohyal
June 30, 2001
From: Bernard Picton
I'm quite certain that your antipodean Janolus cf. hyalinus is not the same
as our NE Atlantic Janolus hyalinus. As you point out in your discussion the digestive gland in true J. hyalinus only extends halfway up the cerata and the pigmentation is quite different. I've seen about 30 animals over the years so I'd have some idea of the range of variation. The photograph of John Chuk's Victorian animal looks similar to ours, but Andrew Green's animals from New Zealand are certainly different.
Upper Right, Lower Left: July 1976 - Lundy Is., Bristol Channel, England. This is the specimen illustrated in Thompson and Brown, 1984 and collected in company with Greg Brown.
Lower Right: Aug 1980 - Lough Hyne (Ine), Co. Cork, SW Ireland (also from batch
of specimens mentioned in Thompson and Brown). Photos: Bernard Picton.
Picton, B.E., 2001 (Jun 30) Janolus hyalinus from Europe. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4685
Thanks for adding some northern European input. I have included your information on feeding and egg laying to a separate message. When I get a chance I will prepare a more informative header page for this species.
June 30, 2001
From: Bernard Picton
UPPER: on bryozoan colony Scrupocellaria. Sep 1985 - Boreray, St. Kilda, NW Scotland
LOWER: Egg ribbon. Aug 1980 - Lough Hyne (Ine), Co. Cork, SW Ireland. PHOTOS: Bernard Picton.
This St Kilda animal is more brightly coloured than usual, with a tinge of orange on the cerata. St. Kilda is offshore, with very clear water and many of the animals there seem to be extra brightly pigmented. I suspect that the bryozoan food may not be Bugula as stated in Thompson and Brown but Scrupocellaria as in the
upper (in situ) photograph.
email@example.comPicton, B.E. , 2001 (Jun 30) Janolus hyalinus - natural history. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4686
September 4, 1999
From: René Lipmann
This image I send you of a Janolus hyalinus, is taken in the Oosterschelde, Kats harbour, the Netherlands. Depth 11 meters. Date 8-8-99
The Janolus stay on a little shipwreck.
firstname.lastname@example.orgLipmann, R., 1999 (Sep 4) Janolus hyalinus from Holland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1284
Do you see any sign of them feeding? They must be staying on the wreck for some reason. Perhaps the bryozoan they feed on lives there as well?
September 3, 1999
From: Peter H. van Bragt
Location: Zierikzee (Zeelandbrug), de Oosterschelde, the Netherlands
With best regards
Peter H. van Bragt
Peter.vanBragt@ftn.hsbrabant.nlvan Bragt, P.H., 1999 (Sep 3) Janolus hyalinus from the Netherlands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1264