Photographed by Bette Jackson



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Hi, I'm Dr. Jerry Jackson, out with the wild things. Dolphins have a conspicuous domed-shaped bump on the forehead, but a look at the skull of a dolphin reveals not a bump but a similar shaped depression on the forehead. The depression cradles a special organ known as a 'melon' because it's shaped like a small melon. The melon is filled with oil and it's the melon that creates the dolphin's forehead bump. A dolphin's oil-filled melon serves as a lens, allowing the dolphin to focus sound in much of the same way that you might focus sunlight with a magnifying glass. That sound is used in communication, as a sonar-like aid in navigation, and as a tool used in hunting. Just as focused sunlight concentrates solar energy enough to start a fire, a dolphin's focused sound energy is strong enough to disorient, stun, or even kill a fish. The sources of the dolphin's sound are its nostrils, located just behind the melon. The dolphin's nostrils have moved back to near the top of the head where they share a single opening for breathing. The bony chambers of the nostrils are different in size, allowing the dolphin to produce different sounds with each nostril, thus increasing its vocabulary.