Tritonia nilsodhneri colour

Dear Ricardo,
You raise some interesting questions. Have you seen the section on colour in nudibranchs. Some of your questions are discussed there. Certainly some nudibranchs get their pigment from their food so are very well camouflaged, although in species such as the sponge-feeding Rostanga arbutus, they also have bristles all over he back so when they crawl off the sponge and are no longer hidden, they are disguised as a small bit of inedible sponge.

But to your tritoniids. I am not sure if anyone has studied whether the pigment in this species is from their food or a result of their own genetic makeup. Without some experimentation its not possible to say if the presence of one or two pink animals amongst a large population of grey animals on a grey gorgonian, means they are recent arrivals still trying to change colour, or just a couple of animals which are showing the 'pink' phase of the species genetic makeup. If it is genetic, then although it may make life a little dangerous for them, the pink ones are incredibly valuable for the species because they are the variation which gives the species the chance to survive in an area where only pink gorgonians exist.

About other defences. Gorgonians have a great store of nasty chemicals in their tissues, and often gorgonian feeders incorporate some of these chemicals in their own tissues to deter potential predators. Again I am not sure if Tritonia nilsohdneri has been examined for such chemicals but I suspect it probably has such
anti-feedant chemicals in its skin as a second line of defence.
Best wishes,
Bill Rudman