Smithsonian.com

Photo: Rickydavid

Human fingertips are exquisitely sensitive to texture and touch, but they’ve got nothing on crocodilian jaws. Thousands of tactile microscopic bumps cover the jaws of American alligators and Nile crocodiles, new research found, helping to snap them into action at the slightest detection of prey swimming in the murky waters of the animals’ habitats.

To arrive at this conclusion, researchers dissected some of these so-called tactile domes. Beneath the domes, they found bunches of nerve endings, a special structure that senses vibrations and clusters of cells that respond to sustained pressure. The entire jaw, they found, contained an intricate, delicate network of nerves. “The innervation of these jaws was incredible,” the researchers commented in a statement.

To see just how sensitive the crocs’ and gators’  jaws were, the researchers gently touched one of the domes with a tiny hair —a method commonly used to measure human touch sensitivity. The animals  jaws proved even more sensitive at detecting these seemingly minuscule stimulants than human fingertips.

When the researchers observed captive Nile crocodiles at night, the predators reacted to the smallest stirring of prey within 50 milliseconds. But they’re not just snapping at any log that comes floating by, the researchers say. Their fine-tuned sensitivity allows them to distinguish between unpalatable debris and tasty prey in a split second. This physiological feature may also explain how mother crocodiles can dexterously aid their hatching young escape eggshells with their jaws without accidentally taking a nibble or two.

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