Why do Indo‐Pacific bottlenose dolphins (Tursiops sp.) carry conch shells (Turbinella sp.) in Shark Bay, Western Australia?

Abstract

Indo-Pacific bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, exhibit a remarkable array of foraging tactics within a single population (Mann and Sargeant 2003). Those described in some detail to date include: “kerplunking,” whereby dolphins scare fish out from vegetative cover with a percussive, bubbleforming tail slap in shallow waters over sea grass beds (Connor et al. 2000); “beaching,” involving intentional stranding on sandy beaches in the pursuit of fish (Sargeant et al. 2005); and, perhaps most notably, “sponging,” in which particular matrilines of dolphins apparently use marine sponges as protective “gloves” or shields over their rostra when foraging in the benthos (Smolker et al. 1997, Kr¨ utzen et al. 2005). Here, we add a new, rare behavior to this extensive list, hereafter referred to as “conching.”