Dolphins use sponges to catch fish

A new study found that some bottlenose dolphins gather up sea sponges in their jaws and use them to uncover fish hidden under the sand – but the behaviour is largely restricted to females for unknown reasons. This is the first and only clear case of tool-use in a wild dolphin or a whale.

In animal species that use tools – such as the chimpanzee – usually all individuals in a population use the tools. But in one population of dolphins, in Shark Bay, Western Australia, only 41 dolphins, in a population of thousands, are known to use sponges.

The scientists found that the "spongers" would slowly swim along the sand of the sea floor, intermittently disturbing it with the sponge in order to find small burrowing fish such as the spothead grubfish (Parapercips clathrata). Their survey also revealed that spongers are nearly all female and the behavioral trait is often passed from mothers to daughters.

Because there is a wide variety of prey available to bottlenose dolphins, but each prey species is highly adapted to escape predators, individual dolphins specialize in different hunting techniques.

Original article here.