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The Sensitive Alligator
Tiny Face Bumps Help Predator Detect Victim
 Listen to Christopher Joyce's report.
University of Maryland doctoral student Daphne Soares holds the skull of a gator she calls "Sammy."
Photo: Vikki Valentine, NPR News
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Tiny bumps that line the jaws of alligators are actually specialized sensory organs that can detect and locate small movements in the water surrounding a gator.
Photo: Adam Britton
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Alligators wait, half-submerged, for their land-bound prey to come to water for a drink. According to Soares' research, gators detect the water disturbance through the bumps, and instantly attack.
Photo: Adam Britton
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May 15, 2002 -- It's not often that a novice scientist discovers something that the experts have missed. New research in the journal Nature reports on an overlooked body part that was in plain view -- the snouts of alligators. NPR's Christopher Joyce has the story on a study that reveals how truly sensitive an alligator is.
The first time Daphne Soares sat on an alligator was in the back of a pickup truck, riding through the swamps of Louisiana. She noticed that the 8-foot-long gator had dots all over its face.
Soares, a graduate student at the University of Maryland, asked around about the dome-shaped bumps, and discovered that nobody had studied them very closely. Soares found herself with a new research project on her hands.
She put young alligators in a small tank and inserted delicate probes into a big nerve in the skull that runs to the brain. The dots were connected to that big nerve, and she discovered that the dots sense pressure changes on the water's surface.
Alligators hunt with their faces half-submerged in water. When something hits the water, the dots send a signal to the gator's brain and the gator lunges at the source.
The dots, called dome pressure receptors, are so sensitive they can detect a single drop of water.
Researchers think the bumps may serve other functions as well; Soares is looking into that. Meanwhile, she suspects there may be a creature even more sensitive than alligators: the crocodile. They have dome receptors all over their bodies -- even inside their mouths.
Other Resources
• Hear crocodilian calls and learn to speak croc.
• Learn how fast gators and crocs run, how long they live and get reptile lore at crocodilian.com.
• Find more about Soares' research are her Web site.
• University of Maryland Neuroscience and Cognitive Science Program
• Nature online.
More NPR stories about crocodilians:
More than 100 million years ago, a crocodile-like reptile that was as long as a school bus lived in Africa. Listen to Richard Harris' report about new insight into how these hyper-giant crocodiles lived and grew.
The venerable Florida tourist attraction known as alligator wrestling is hemmed in these days by Super Bowls, casinos, Disney World, and declining interest among Seminole Indians. From Hollywood, Fla., Pippin Ross reports.
Robert Siegel talks with Kevin Foster, former owner of Florida's largest alligator farm. Foster inherited the farm from his father, but he decided to get out of the business. He talks about what it's like to run such a business.
Scott Simon speaks with Jim Metzner, producer of the radio feature Pulse of the Planet, about Nile crocodiles.
Scott Simon speaks with children's book author Daniel Pinkwater about a new book called I, Crocodile, by Fred Marcellino (Harper Collins).
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