The secret behind those jaws

Associated Press

Alligators locate their prey in the swamps by using nerve-packed bumps on their jaws so sensitive that they can detect ripples from a single drop of water, a study says.

Alligators have hundreds of such bumps that cover the face like a beard, said Daphne Soares, who recently finished work toward her doctorate at the University of Maryland.

Half-submerged alligators rely on the sensory array to pinpoint splashes, whether caused by a fallen hatchling or an animal stooping for a drink, Soares said.

“These are armored creatures, but they have developed this elegant way to be sensitive to their environment,” she said. Her study appears in today’s issue of the journal Nature.

Fossil evidence suggests the sensory ability emerged 200 million years ago in the ancestors of modern alligators.

Soares first noticed the honeycomb of bumps while sitting atop an 8-foot bull alligator “hog-tied and duct-taped” in the back of a pickup truck as they bounced down a Louisiana back road. She had been studying the auditory similarities alligators share with birds.

Previous research described the bumps simply as sensory organs but did not elaborate. Soares, her curiosity piqued, began studying Louisiana alligators she had flown to laboratories in Maryland and Massachusetts.

She found the nerve endings in each bump fed through the bone and led to the largest nerve in the alligator’s skull – a nerve so big she initially mistook it for a muscle.

Creating ripples in the tank where anesthetized alligators floated, half-submerged, stimulated the nerve in a way light, electricity, food and other stimuli did not, she said. When she dribbled water into the darkened tank, the alligators would lunge toward the spot.

To ensure it was the dripping that provoked the reaction, she plugged the animals’ ears with petroleum jelly. Even without hearing or seeing, and with nothing to smell, the gators would pounce repeatedly, even on a single drop.

“Once they sense a drop of water, they go toward it and bite it. Some kept biting it. They didn’t believe there was nothing there,” Soares said.