Abstract

During night dives along randomly selected transects across sand, seagrass, and rubble on the reef flat of Looe Key, a spur-and-groove coral reef, spiny lobsters (Panulirus argus) from dens on the forereef were observed foraging on the reef flat, particularly on the extensive rubble ridge and also relatively frequently in Thalassia. Subsequent sampling of the rubble revealed hundreds of taxa of appropriate prey items, many at high densities; the density of Cerithium litteratum, a favoured food item, was as high as 180 individuals m^-2. Arthropods, especially spider crabs (Pitho spp.), were common in seagrass. Gut contents of 75 intermoult lobsters caught on offshore reefs at Biscayne National Park and Dry Tortugas National Park included a myriad of prey items, predominantly molluscs—especially gastropods (49%), chitons (15%), and bivalves (11%)—and arthropods (12%); many of the species in lobster guts were rubble dwellers, but some guts contained multiple prey peculiar to seagrass and sand. It is concluded that Panulirus argus can forage successfully wherever suitable prey items, especially molluscs, are abundant. However, where a wide range of substrata, including rubble, is available, rubble is preferred because of its abundant, accessible prey.