Journal of the Marine Biological Association of the UK



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


M.S.  Grisley a1, P.R.  Boyle a1, G.J.  Pierce a1c1 and L.N.  Key a1
a1 Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland

Abstract

Octopuses (Eledone cirrhosa) feeding on crabs (Carcinus maenus) may penetrate the crab by a carapace borehole or puncture of the eye. In ad libitum feeding trials (632 crabs eaten), 31% of the predated crabs had a punctured eye, 57% had a borehole in the dorsal carapace. Eye puncture and boring occurred 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 showed 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. Increasing the proportion of small crabs in the diet increased the subsequent incidence of carapace boring at all crab sizes. The results are discussed in relation to differences in prey handling efficiency at different prey sizes.


Correspondence:
c1 Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland