Use of crustacean burrows as habitat by the marine snail Circulus cinguliferus (Gastropoda: Truncatelloidea: Vitrinellidae)

The family Vitrinellidae is a group of tiny marine snails that generally occur in shallow waters of temperate and tropical seas. The biology of most vitrinellid species remains poorly understood. In this study, we report that Circulus cinguliferus (A. Adams, 1850) (Vitrinellidae), distributed widely in the warm shallow waters of the Pacific, inhabit crustacean burrows, including those of the mud shrimp Neaxius acanthus (Strahlaxiidae) and snapping shrimp Alpheus rapax (Alpheidae), in the intertidal and subtidal flats of the Okinawa Islands, southern Japan. They exhibited highly clumped distribution among the host burrows, suggesting that they are attracted by conspecifics. Although the biology of most Circulus species remains unknown, Circulus texanus (D. R. Moore, 1965) is known to inhabit stomatopod burrows in the western Atlantic. Our findings suggest that such a commensal habit may be more widespread in this genus than previously thought.