Which dolphin species is known to use marine sponges as tools for foraging?

The Indo-Pacific bottlenose dolphin is known to use marine sponges as tools for foraging. In Shark Bay, Western Australia, some dolphins place a conical sponge over the tip of the rostrum while searching the seafloor for prey.

This behaviour, called “sponging,” appears to protect the sensitive rostrum as the dolphin probes sand and rough substrate. The dolphins often target bottom-dwelling fish that lack swim bladders, prey that can be difficult to locate using the usual combination of echolocation and vision.

Sponging is one of the clearest examples of socially learned tool use in a wild cetacean. Young dolphins typically acquire the technique from their mothers, and genetic studies indicate that many spongers descend from a single maternal line. The behaviour is strongly female-biased and usually begins during the dolphin’s second year.

Spongers tend to make deeper dives and spend more time foraging than non-spongers. They may carry the same sponge for several surfacings, though they sometimes replace it. The behaviour has also been observed with conch shells, which dolphins use to scoop fish from the seabed.