Nudibranch, Kelp and Mussel

June 13, 2016


Photographer: John Stetson
Summary Author: John Stetson

The nudibranch featured above was captured from a dock just a few inches below the waterline in South Portland, Maine -- at Southern Maine Community College. These odd looking mollusks often appear near mussels, another mollusk. Unlike mussels, which have hard, protective shells, nudibranchs (literally meaning naked gills) have other means of protection. The orange colored appendages on this creature aren't legs at all; rather they're cerata. At the end of the cerata are cnidosacs, stinging cells called nematocysts. The bright color is a characteristic of aposematism, warning colors of poisonous animals. Also in this specimen bucket, belonging to marine biologist Megan McCuller, is a mussel covered with bryozoans (bottom), kelp, and hydroids (upper right-hand corner). Hydroids are a source of food for nudibranchs.