In 1984, researchers spotted dolphins doing something unusual in Shark Bay, Western Australia. When the animals got hungry, they ripped a marine basket sponge from the sea floor and fitted it over their beaks like a person would fit a glove over a hand. The scientists suspected that as the dolphins foraged for fish, the sponges protected their beaks, or rostra, from the rocks and broken chunks of coral that litter the sea floor, making this behavior the first example of tool use in this species.
In a new report out in PLoS ONE, it is shown that these dolphins go through all this trouble to protect their beaks because fish from the sea floor are more nutritious. This is an alternative to fishing in the open ocean.