Sea slugs, informally grouped as the Opisthobranchia, are
subdivided into numerous (sub-)clades, including the Aplysiomorpha
(sea hares), Sacoglossa (sap-sucking slugs), and
the large subclade of the Nudibranchia (true nudibranchs)
(Bouchet and Rocroi 2005). Predation by sea anemones has
only been reported for the Aplysiomorpha (e.g. Winkler and
Tilton 1962; Johnson and Willows 1999). For the Sacoglossa
there are records of predatory attacks by other sea slugs,
as well as feeding experiments with fish and crabs
(Trowbridge 1994). The majority of the predation records
for the subclade Nudibranchia consist of attacks by other
sea slugs (Rudman 2000).
Sea anemones are sedentary organisms, and are considered
opportunistic feeders; their diet includes crabs, fish,
sea urchins and zooplankton (Ruppert et al. 2004). The sea
anemone in Fig. 1 is identified as belonging to the family
Edwardsiidae, although it has been erroneously referred to
as Condylactis sp. (e.g. Colin and Arneson 1995: fig. 565;