Only female dolphins seem to do this, usually in a particularly deep channel. The dolphin-watchers are still trying to figure out why the dolphins do it, but Connor and his colleague Dr. Rachel Smolker of Harvard University think that they use the sponges to protect themselves from the poisonous spines of deadly stonefish while foraging along the sea floor. For years scientists thought that using tools was the singular privilege of humans.
Dolphins now join chimps and even some birds as tool users.