Gator attack methods revealed

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While watching a group of young alligators swimming in a biology lab, U doctorate student T. J. Uriona noticed that the water didn’t ripple when the alligators changed their positions. Uriona and his biology professor, Colleen Farmer, decided to investigate the peculiarity and discovered that alligators have an evolved tool for attacking prey.

A young alligator can contract its stomach muscles and pull air in the lungs closer to its tail. With air near the tail, it rises and helps adjust the alligator’s position without disturbing the water and revealing its location. This also allows a young alligator to dive into the water for an attack.

“If (young alligators) wanted to change the angle of their body to help them capture prey, it would help them get into the right position without causing ripples,” Farmer said.

Alligators can move more gracefully through the water because they aren’t actually pushing on the water and moving it, she said.

Animals move through water by generating lifts and flaps to swim and attack prey. The air in an alligators’ lungs can creates a buoyant effect by shifting the lungs toward the tail, lifting the tail higher and requiring the alligator to use less effort in movement.

“Air underwater is buoyant,” Farmer said. “It tries to rise to the surface.”

Scientists used to believe that the muscle movement was only used to help alligators breathe. Uriona’s study proves that by moving the lungs toward the tail, alligators are more adapted to moving through the water.

This muscle movement may be an evolved ability that alligators acquired during the Cretaceous period, although there is no solid proof.

“We are suggesting that it evolved when they went back to an aquatic lifestyle,” Uriona said.

Alligators were about the size of a cat when they walked around on land before the Cretaceous period.

Researchers haven’t seen alligators push the lungs toward their heads, but they aren’t ruling out the possibility that they could. Alligators would have to squeeze their abdomens and push the lungs up, but it could happen, Uriona said.

When an alligator pushes its lungs toward its tail, the belly expands and the chest gets smaller as the internal organs are pulled back. The lungs don’t separate from other organs when moving back. The air in the lungs is what makes the tail move.

Biologists don’t know exactly how far the lungs need to move to change the position of the alligator, but researchers plan to investigate this.

“That would be our next step,” Farmer said.

There is a possibility that alligators can also pull the lungs further right to help them roll through the water to choke and tear their prey.

The study was conducted with two-year-old alligators. No tests have been done on alligators older than eight years.

“It would be difficult to work with adult alligators, but they likely have the same ability,” Farmer said.

Other amphibians might also have this ability. Uriona and Farmer are completing a six-month study that tests the muscle movement in frogs and turtles.

The study shows that although turtles use the muscle movement for both breathing and silently adjusting their positions, frogs only use muscle movement to change their positions. This might disprove common scientific belief that frogs use it for breathing.

The study will be published in the April 2008 edition of The Journal of Experimental Biology. The study was published online on March 14.

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