A Really Keen sea slug
The sea slug in this picture is the nudibranch Tritonia myrakeenae, which was first described in La Jolla, California in 1986 and named after a famous biologist/malacologist A. Myra Keen (She was a professor at Stanford University). It is usually very tiny (5-10 mm) though it can reach up to 18 mm. In La Jolla, it feeds on the octocoral Clavularia. Tritonia myrakeenae has the same peachy color as its prey Clavularia and is hard to spot. The Clavularia colony grows using creeping stolons and the polyps arise at regular intervals from the stolon. The extended polyps of Clavularia look rather like gill tufts on the back of the Tritonia. The only hole in this Tritonia’s camouflage are the two what spots on the usually present on the dorsum.
Tritonia myrakeenae ranges from Santa Barbara, CA through Isla Cedros, Baja California, Mexico and has been found in Costa Rica. With a range this large it seems odd that it wasn’t described till 1986. In parts of its range outside of California, it feeds on other octocorals and gorgonians.
This picture was taken at South Casa Reef (Hospital Point), La Jolla, CA. Tritonia myrakeenae is in the suborder Dendronotacea (Trapania velox below was in the suborder Doridacea.)
References
Behrens, D.W., and Hermosillo, A. (2005). Eastern Pacific Nudibranchs: A Guide to the Opisthobranchs from Alaska to Central America. Sea Challengers, Monterey, CA.
Bertsch, H. and Mozqueira, O.A. (1986). A new species of Tritonia (Nudibranchia) from southern California and Baja California. The Nautilus 100(2): 46-49.
The Sea Slug Forum - Tritonia myrakeenae