• Norwegian: brun frynsesnegl

Characteristics:

Color is a very uncertain method of identification. In Norway grey and orange color variations are common. Brown, yellow, red or white individuals can be found too. Hidden among the white tipped cerata, there is sometimes a white line running along the back. F. verrucosa is normally 15-25 mm long, but individuals reaching more than 60 mm have been reported. It lacks the small warts on the rhinophores (tentacles on the head) seen on the Flabellina nobilis. Some of the pictures above indicate that the anterior corners of the foot are rounded. Others have reported a more angular shape of the foot. This may suggest that we actually are talking about more than one species. It sometimes hosts the colorful parasite L. agilis.

Habitat:

F. verrucosa has been reported on all depths down to 300 metres. Sand or rocky substrate on current exposed locations seems to be preferred. If is usually encountered grazing on hydroids.

Distribution:

It is widespread in the North Atlantic Ocean and also reported from the North Pacific Ocean. The wide range of coloration of this species may have confused some of the reporters.

Taxonomy:

The taxonomy of the F. verrucosa is uncertain. The original identification of the species was done in 1829, and accompanied by a drawing (check The Sea Slug Forum) very similar to the images presented here. The drawing and the image show the same ice-cone-shaped, white-tipped, quite short cerata. Other individuals shown on The Sea Slug Forum and by Moen and Svensen (2004) have significantly longer and slimmer cerata in a very different pattern on the back. They also lack the clearly visible hump (the heart). Some of them look very much like F. nobilis to me. I am not convinced that identification solely from pictures is possible in many of these cases. The individuals shown on this page are very close to the original drawing by M. Sars, and there is little doubt that these are real F. verrucosa. The experts seem to agree that more research is needed to clarify if what we call F. verrucosa is actually more than one species.