Tool-Use in Wild Bottlenose Dolphins

Abstract

This chapter discusses the tool-use in wild bottlenose dolphins. Tool-use is generally defined as the exertion of control over a freely manipulable external object (the tool) with the goal of altering the physical properties of another object, substance, surface, or medium via a dynamic mechanical interaction;. Once considered the defining feature of hominids, tool-use is rare in wild animals. Although 10 primate species and 30 bird species are known to use tools, only 0.01% of non-primate mammalian species have been documented using tools in the wild. In Shark Bay, Australia, a subset (11% of adult females) of the Indian Ocean bottlenose dolphin (Tursiops aduncus) population uses marine sponges as foraging tools. This itself is remarkable because tool-use is typically common to all or none of the individuals within a population. Thus, despite interaction between tool-users and non-tool-users in Shark Bay, only specific individuals adopt tool-use as a foraging method, indicating individual specialization in the use of foraging tactics and probably prey species. Shark Bay is unlikely to be the only place where wild dolphins use tools. There are definitive anecdotal accounts of Indo-Pacific humpback dolphins (Sousa chinensis) carrying sponges in other parts of coastal Australia.