João Pedro Silva

Don't worry, they use smell to tell their mates from the preys :)

Thanks, António. Sharing information was what motivated me to start documenting nudibranchs in Portugal 15 years ago.

Thanks for the distinction, Daniele.

Thanks, Leuba. There's a large number of species which live in very shallow water so they're often missed by divers (most of whom think that diving shallower than 10 meters is not "real diving") and also by snorkelers and free divers (most of whom can't really spend enough time underwater to look for very small creatures). Too deep for some, too shallow for others, these species stand in a sort of "depth limbo". But some also have strange habits like being more active in the winter when there are few people willing to dive. So you have to actively look for these animals and study their habits before you see them.

Thanks, Mark and Leuba. I've been documenting local species of nudibranchs for the past 15 years mostly because there was little information available. Believe it or not, the only field guide available for Portugal until 2008 had only half a dozen nudibranchs.

Thanks, Mark. The juvenile form is retained at least until they reach 20 mm. Then they start growing very fast and reach 100 mm easily. The adults are voracious predators and feed on many species of soft corals. Juveniles are difficult to find because they're small and mostly transparent. Adults are difficult to find because they usually live deep, beyond recreational diving limits (~40 meters deep) and also because they're well camouflaged: the bright red is rendered as dark green because the water absorbs most of the red component of the natural light.
If you set a slideshow on flickr with 5 seconds for each image you'll be done in less than 12 hours :)

Thanks, Mark. There are actually several nudibranchs with very good camouflage. I've still many to include but if you browse through my spottings you'll find several species which are far from being exuberant.

The ringed rhinophores, purple pigment on the surface of the cerata (especially near the tip) and the stalked ceratal clusters differentiate Flabellina affinis from Flabellina pedata. Regarding "common" names, very few names have genuine common names so get used to the latin names. There's a very good post about this subject at the Sea Slug Forum: http://www.seaslugforum.net/find/common

The subapical purple pigment is characteristic of Flabellina affinis. The ringed rhinophores also enable to differentiate from F. pedata.

It's not so difficult to distinguish the three "purple Flabellinas" which occur in this area but one must make sure the characteristic features are captured on the photo. Nevermind the white tips on the cerata: all 3 may have them. Flabellina pedata has almost smooth rhinophores and the cerata transparent cerata (the color is given by the digestive gland inside) grow directly from the body. Flabellina ischitana has conspicuous rings on the rhinophores and each ceratal cluster has a raised peduncle at the base from which the cerata grow. Flabellina affinis also has conspucuous rings on the rhinophores and also the peduncles on the ceratal clusters but the wall of the cerata has purple opaque pigment at the surface, usually more concentrated below the tip and sometimes even absent from the base of the cerata. There is also a recently described species, Piseinotecus soussi, which has a purple body but the cerata are covered with minute white specks and dots. Piseinotecus gaditanus also has a pink body (although much faded) but is very small and rare. Recent DNA studies have shown the above mentioned Flabellina spp. are more closely related to Piseinotecus gaditanus and Piseinotecus gabinierei than to other species of the same genus like Flabellina babai. The next revision of the Flabellinidae will probably change the genera of some of these species (if not all).