Janolus hyalinus
(Alder & Hancock, 1854)

Order: NUDIBRANCHIA
Suborder: ARMININA
Family: Zephyrinidae

DISTRIBUTION

Eastern Atlantic from Isle of Man, and Northern Ireland, France, western Mediterranean and Morocco. Also recorded below from the Netherlands.

PHOTO

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.

Reference:
• 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

Related messages


Janolus hyalinus from Europe

June 30, 2001
From: Bernard Picton

Hi Bill,
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.

PHOTOS:
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.

Bernard

bernard.picton.um@nics.gov.uk

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

Dear Bernard,
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.
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Jun 30). Comment on Janolus hyalinus from Europe by Bernard Picton . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4685

Janolus hyalinus - natural history

June 30, 2001
From: Bernard Picton


Dear Bill,
To accompany my other message, on the identity of Janolus hyalinus, here is an in situ photo of an animal on its food, and a photo of an egg ribbon.

PHOTOS:
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.

Bernard

bernard.picton.um@nics.gov.uk

Picton, 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

Thanks Bernard,
Bill Rudman

Rudman, W.B., 2001 (Jun 30). Comment on Janolus hyalinus - natural history by Bernard Picton. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4686

Janolus hyalinus from Holland

September 4, 1999
From: René Lipmann

Bill,
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.

Greetings
René Lipmann
Diveteam Manta,
Amsterdam

lipmann@bvd.nl

Lipmann, R., 1999 (Sep 4) Janolus hyalinus from Holland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1284

Thanks René,
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?
Bill Rudman.

Janolus hyalinus from the Netherlands

September 3, 1999
From: Peter H. van Bragt

Dear Bill,

Here is a photo of Janolus hyalinus to add to the Netherlands' List.

Location: Zierikzee (Zeelandbrug), de Oosterschelde, the Netherlands

With best regards
Peter H. van Bragt

Peter.vanBragt@ftn.hsbrabant.nl

van 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