We humans tend to favor animals that behave like we do.

Dogs? We love their sociability and playfulness. Chimpanzees? Like contestants on Fear Factor, they use sticks to scoop maggots and other insectival snacks from dung piles. We can relate to that. Dolphins? Who can resist their smiling jaw lines, frolicking behavior, and chirping vocabulary?

Scientists have discovered another reason for us to favor dolphins. Like chimps, dolphins use tools to look for food, but while chimps use sticks, a handful of dolphins in Australia's Shark Bay use sea sponges. While poking around for snacks on the ocean floor, dolphins are likely to get stung by spiky creatures that hide in rocks and in the sand. Some female dolphins in Shark Bay have figured out that protecting their snouts with sponges is a good way to keep from getting stung.

How did these dolphins come to cover their noses? At first scientists suspected that genes played a role. In fact, samples taken from the dolphins' DNA showed that all but one of the sponge users are related. However, other evidence suggests that using sponges is not an inherited trait. Instead, scientists now think that dolphin sponge users learned the trick from other dolphins. In other words, at least for this small group of dolphins, using sponges to protect themselves is part of dolphin culture.

We've known for a long time that dolphins are smart. Now we can add them to the distinguished list of animal tool users. Just imagine what dolphins could accomplish if they had opposable thumbs!