Factors affecting prey handling in lesser octopus (Eledone cirrhosa) feeding on crabs (Carcinus maenas)

Octopuses (Eledone cirrhosa) feeding on crabs (Carcinus maenus) may penetra te the crab by a carapace borehole or puncture of the eye. In ad libitum fe eding trials (632 crabs eaten), 31% of the predated crabs had a punctured e ye, 57% had a borehole in the dorsal carapace. Eye puncture and boring occu rred together in 6% of cases but 18% were neither punctured nor bored. Feeding trials in which size of prey and size of octopus were controlled sh owed that the incidence of boreholes was greatest (> 70%) in small crabs (< 50 mm carapace width). Incidence of eye puncture (10% in small crabs) rose to 25% in crabs of over 50 mm carapace width and to over 40% in the largest crabs used (65-80 mm carapace width). Large octopuses used eye puncture less frequently than small octopuses. Inc reasing the proportion of small crabs in the diet increased the subsequent incidence of carapace boring at all crab sizes. The results are discussed i n relation to differences in prey handling efficiency at different prey siz es.