Patterns of shell penetration by Chorus giganteus juveniles (Gastropoda : Muricidae) on the mussel Semimytilus algosus

Patterns are described for shell penetration by the sublittoral muricid sna il Chorus giganteus during predatory attacks on the mussel Semimytilus algo sus. Location, form and size of shell penetrations were observed in relatio n to the size of the predator. The results suggested that positions of the perforations on the mussel shells were related to size of the attacking sna il. Smaller snails perforated areas near the shell ligament and in the cent ral zone of the shell, while larger snails more frequently attacked shell b orders, principally on the ventral side. These observations may be related to: (a) changes in the process of manipulation of the prey during developme nt of the foot and the shell tooth of the predator, (b) changes in internal structure of the snails related to the shell perforation mechanism, or (c) learned behavior acquired experientially by the snails during early growth . Although in other studies of muricid penetration patterns larger borehole s made in shells of the prey were positively correlated with increasing pre dator size, this relation did not appear to hold with C. giganteus. as larg er specimens often made relatively small shell perforations. Areas of boreh oles made in the mussel shells by this snail varied from 0.01 to 1.1 mm(2), and were unusually variable in size and shape, especially when compared wi th literature results on bores characteristic of other muricid species. (C) 2001 Elsevier Science B.V. All rights reserved.