Predation by the Nudibranch Dirona albolineata on Three Species of Prosobranchs'

NUDIBRANCHS as a group prey on a diverse assemblage of animals including sponges, coelenterates, tunicates, barnacles, crustaceans, ectoprocts, polychaetes, egg masses, and carrion (see review papers of Miller, 1961; Swennen, 1961; Thompson, 1964) . Only a few nudibranchs are known to prey on other molluscs, usually opisthobranchs. These include: Gymnodoris alba (Bergh, 1877) which eats Favorinus sp. and Aeolidella sp.; Gymnodoris bicolor (Alder and Hancock, 1866) which eats G. okinawae Baba, 1936 and G. plebeia (Bergh, 1877) (see Kay and Young, 1969); Phidiana pugnax Lance, 1962 which eats other eolids (Lance, 1962); and Roboastra sp. which eats Nembrotha eliora Marcus, 1967 (Farmer, personal communication). Hermlssenda crassicornis (Eschscholtz, 1831), in the laboratory, will eat other nudibranchs including its own species, but this behavior is likely to be caused by starvation and is of little importance in the field (Swennen, 1961). In this paper, I report some observations on predation by a nudibranch , Dirona albolineata MacFarland, 1912, on three species of prosobranchs in nature and in the laboratory.