Observations on the feeding habits of the shark Heterodontus francisci Girard 1854 (Chondrichthyes: Heterodontidae), in San Ignacio Lagoon, Baja California Sur, Mexico

Abstract

A total of 108 stomach contents of horn shark (Heterodontus francisci) from San Ignacio Lagoon were analyzed. This species occurred all year round, with low abundance in summer and fall. The index of relative importance (IRI) was used to determine the prey importance. The horn shark feeds mainly on benthic invertebrates, such as gastropods (Lucapinella milleri and Calyptraea spp.), crustaceans (Callinectes bellicosus, Penaeus spp. and isopods), pelecypods (unidentified), sipunculoids (Sipunculus nudus), cephalopods (Octopus spp.), as well as on small fishes (Syngnathus auliscus). This shark is a third-order consumer, because it is a predominantly carnivorous benthic species; it is a selective predator with nocturnal or crepuscular habits.