March 2005 Unknown

Butterfly of the Sea � Dendronotus

One of the most fascinating groups of organisms in the sea is the Subclass Opisthobranchia, Order Nudibranchia -- the nudibranchs. Opisthobranchia means "opposite gilled" referring to the position of the gill of these animals in comparison to that of typical snails. In the development of snails, the body becomes coiled, with the gill twisted back to the head region through a process called torsion. Nudibranchs and other opisthobranchs look like snails during their early larval stages, but as they develop, they �straighten out� (de-torsion) to become more slug-like in body form. In fact, they are often called 'sea slugs'. But the name doesn't do justice to this diverse and often strikingly beautiful group of marine snail relatives. Most nudibranchs are somewhat specialized predators, and they feed on a variety of marine life including even anemones and jellyfish. Many species that do this (most are in the Aeolid group of nudibranchs) can capture and utilize the anemone's stinging-cells for their own defense. This lovely species, Dendronotus, is not an Aeolid nudibranch, and although it feeds on some members of the phylum with stinging cells (The Cnidarians) it does not harbor the stinging cells in its lovely branched 'cerrata'. For a full program about nudibranchs and other members of the Phylum Mollusca, see our program on video, DVD, or digital download, Branches on the Tree of Life: Molluscs. Also check our gallery on animal phyla.

For a concise and revealing teaching video about Arthropods, get our video/DVD: Branches On the Tree of Life: Arthropods. For a rich overview of marine intertidal ecology, see our program: The Biology of Seashores.