Dendronotus robustus from Spitzbergen, Nth Atlantic

March 7, 2007
From: Erling Svensen

Dear Bill,
I have been diving at Svalbard (Spitzbergen) in the Arctic Ocean, quite far to the north of Norway (aprox. 80 degrees) while on voyages on the research vessel Jan Mayen. In Kongsfjord with Ny Aalesund, just out from the glacier, I came across this Dendronotus robustus. At that time, in 2002 - I was using film, so I show only two pictures. One of an adult, more than 15 cm long, and one juvenile. I enclose the pictures. The water temperature was minus 1 degree Celsius and the depth aprox. 15 meters on a very silty bottom.

Locality: Svalbard  (Spitzbergen), 15 metres, Norway, Arctic Ocean, 2002, Very silty bottom out of a glacier. Length: 15 cm.. Photographer: Erling Svensen.

Thanks for very nice and helpful WEB-pages. Here is a new one for the Forum.

Best regards
Erling Svensen

Svensen, E., 2007 (Mar 7) Dendronotus robustus from Spitzbergen, Nth Atlantic. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Erling,
I felt very cold just reading your message. Thanks very much for these photos of Dendronotus robustus. It is indeed a new one for the Forum and I don't recall ever seeing a photo of this species alive before.

Although Gordon Robilliard listed a number of differences between D. robustus and his new species D. albopunctatus, from the NE Pacific, they certainly look very similar externally. Do you know much about the biology of Dendronotus robustus? My first thought when seeing your upper photo was just how similar in body shape it is to a number of other unrelated opisthobranchs which live on soft sediments such as Euselenops luniceps and Kalinga ornata [see Fact Sheet], with a relatively wide foot, wide oral veil with tentacles along the edge, and flattened body. It would be interesting to know if D. robustus is also a burrower.

We know little about this species, which was first described by Verrill (1870) from Massachusetts, on the Atlantic coast of Nth America, and a few years later from Norwegian waters by Sars, (1878) as Dendronotus velifer. Thanks for this very interesting addition to the Forum.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Mar 7). Comment on Dendronotus robustus from Spitzbergen, Nth Atlantic by Erling Svensen. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from