Crustacea in the Diet of Eledone Cirrhosa (Mollusca: Cephalopoda) determined by Serological Methods

Abstract

Serological methods for prey identification have been applied to the gut contents of a field sample of 100 Eledone cirrhosa from the Moray Firth and 7 from the Sound of Jura. Protein extracts from the crop were electrophoresed (Laurell rockets) into antisera raised against potential crustacean prey species, Cancer pagurus, Carcinus maenas, Crangon crangon, Liocarcinus spp. and Nephrops norvegicus. The strengths of the resulting reactions were evaluated on the basis of peak height, staining density and the number of homocentric peaks of immune precipitates. Sixty-two of the 100 Moray Firth animals gave a positive reaction to one or more of the antisera and the most critical assessment of the results ranked the incidence of the prey as Liocarcinus (15) > Nephrops (10) > Cancer (8) > Crangon (2) > Carcinus (0), a total of 35 reactions from 28 animals. Absence of a reaction in the 38 animals from which appreciable sample volumes were also obtained indicates that alternative prey had been consumed. Of the 7 Sound of Jura animals, 4 gave a positive reaction to Nephrops alone. A total of only 24 animals gave any indication of diet by visual recognition of remains. The value and difficulties of the methodology are discussed.