Dietary and anatomical specialization of mitrid gastropods (Mitridae) at Rottnest Island, Western Australia

Abstract

Three species of mitrid gastropods, the tropical Mitra scutulata and M. ticaonica and the temperate M. badia inhabit the intertidal platforms of Rottnest Island, Western Australia. All three species feed almost exclusively upon the abundant sipunculan species, Phascolosoma rottnesti. Compared with other neogastropods the Mitra species have a highly modified proboscis with several unique structures: the epiproboscis, peristomal papillae, a broad multicuspate radula and brush-like lining to the buccal cavity, all probably associated with the very specialized diet. Other predatory gastropods coexisting with the Mitra species on the Rottnest platforms, such Dicathais orbita, Cronia avellana, Conus dorreensis and Bursa granularis show little or no dietary overlap with the mitrids.