BY The Press Association

Crocodiles and alligators behave like sophisticated submarines to dive, surface or roll sideways without flippers or fins, researchers have discovered.

Biologists in the US found that the aquatic reptiles manoeuvre silently by turning their lungs into internal flotation tanks.

Using their diaphragm, pelvic, abdominal and rib muscles, they shift air towards the tail for diving and towards the head for surfacing. Moved to the left or right of the body, it helps the creature to roll.

Modern submarines use a similar system to adjust their buoyancy, pitch and roll. Air is pumped into different compartments to help a vessel dive or surface.

Scientists made the discovery by studying five young American alligators from the Rockefeller Wildlife Refuge near Grand Chenier, Louisiana.

The animals were only 15-20 inches long, making them much easier and safer to work with than adults which can reach 15 feet.

Electrodes were implanted on five sets of muscles so their activity could be monitored as the alligators swam around in 100 gallon fish tanks.

Four muscle sets were found to be involved in shifting the lungs to help the alligators dive and manoeuvre.

As part of the study, small weights made from shotgun pellets were taped to animals.

Attached to the snout, they helped the alligator dive, causing reduced activity in the muscles needed to help diving. When a weight was taped to the tail, it made diving more difficult and the muscles were found to work harder.

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