The sea cucumber Bohadschia graeffei... Photo Wilhelm van Zyl and the nudibranch it mimics, Phyllidia varicosa Photo Guido Zsilavecz	Nudibranch mimicry The sea cucumber shown was photographed in Indonesia. At first glance it looks remarkably like a stretched-out Phyllidia varicosa, a moderately common tropical nudibranch. The tubefeet just visible give the animal away, and the shape of the feeding tentacles near the head (the fuzzier yellow blobs near the head on the left) clearly look like those of a sea cucumber, especially tropical ones. Mimicry in nature is not uncommon, and there are numerous examples within the nudibranch world. Several flatworms, a few snails and some sea cucumbers mimic different nudibranchs. In one case both a flatworm and a sea cucumber mimic the same species of nudibranch! As nudibranchs are often unpalatable, mimicking them is a good survival strategy - if no predator eats the nudibranch, chances are good it won't touch the mimicking species either. Nudibranchs themselves mimic other species of nudibranch (not all are unpalatable, so those that are not increase their survival by looking like those that do), as well as other species of animal - several mimic soft coral, for example. In our own waters one species, Corambe sp., has a body pattern which looks very similar to the bryozoan it feeds on, as do its egg cases. Thusfar it has managed to elude us, as we are certain only a very careful look (and a bit of luck), will reveal one!
References: Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987. Nudibranch behavior. DW Behrens, 2005 Nudibranchs and sea snails. H Debelius, 1996.
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