First sighting of Geitodoris on Helgoland, North Sea
April 16, 2003
From: Philipp Schubert
Dear Bill,
I just wanted to let you know that we found the first Geitodoris planata on Helgoland in the German Bight, North Sea. The individual was found last summer (2002) while diving in a sheltered harbour ("Südhafen") on a wall with diverse sponges, laying egg ribbons. I wrote my masters-thesis about Nudibranchs on Helgoland (and their interactions with bryozoans, actually) and found this big opisthobranch incidentially while searching for other slugs. It has never been found on this Island before, although it could possibly have been confused with Archidoris pseudoargus, which is quite common here.
With the background of an "explosion" of Geitodoris last summer in the Oostershelde, it is possible that this is a sign for a gradual advance of this species in the North Sea, where it was missing before, if we believe the literature (Thompson & Brown, 1984; Thompson, 1988; Picton & Morrow, 1994).
Sorry that I passed this information on to you so late, but first I thought it was nothing special...
The upper photo was taken in the aquarium from above [All photos were taken by Heidi Zanker]. The star-shaped glands are not quite good visible, but were present.
The lower left illustration is copied out of Thompson & Brown (1984), showing the differences between A Archidoris pseudoargus, and B Geitodoris planata. The lower right photo of the oral region was taken in an aquarium to prove, that this is in fact Geitodoris and not Archidoris.
I really like your site and think it´s a very good possibility to get actual informations about Nudibranchs, so keep on rocking!! In future maybe I´ll try to add some Nudis from Kiel/Baltic Sea, this part of of the world's oceans is still under-represented in your forum, put in fact we have some nice species here, too.
So long,
Philipp Schubert
derschubi@web.de
Schubert, P., 2003 (Apr 16) First sighting of Geitodoris on Helgoland, North Sea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9588
Thanks Philipp,
An interesting find. It's often difficult to know whether a 'new record' means an animal has just arrived or whether it means a human who can identify it accurately has just arrived. I guess that's why Picton & Morrow say 'No records exist for the North Sea coasts', meaning no-one has recorded it from there rather than it doesn't live there.
Whatever the reason, it is good to get new information on even the most common species. I hope you will be publishing information from your masters-thesis and will look forward to seeing it. I also hope you will send us some information on the Kiel/Baltic Sea fauna.
Best wishes,
Bill Rudman
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