THE ANOLE, a small lizard that originates from tropical regions in the Americas, has recently been crowned the world's smallest scuba diver.

The semi-aquatic lizard has been found to evade its long list of predators by darting into water, where it can breathe for at least 20 minutes without resurfacing.

Scientists have known about the anoles' scuba-diving tendencies for some time, they just didn't know why the species was doing it - until now.

New research from Binghamton University, the State University of New York, found that the scrappy species of lizard uses its own breath to create an air bubble that allows it to remain underwater for longer.

Lindsey Swierk, an assistant research professor of biological sciences at Binghamton University, said: "We know that they can stay underwater for a really long time.

"We also know that they're pulling oxygen from this bubble of air.

"We didn't know whether there was actually any functional role for this bubble in respiration.

"Is it something that lizards do that is just a side effect of their skin's properties or a respiratory reflex, or is this bubble actually allowing them to stay underwater longer than they would, say, without a bubble?"

As it turns out, the bubble does allow the anole to remain submerged for much longer than it could without a back-up air bubble.

"Anoles are kind of like the chicken nuggets of the forest. Birds eat them, snakes eat them," added Swierk, who has been researching the anole in the tropical forests of southern Costa Rica.

"So by jumping in the water, they can escape a lot of their predators, and they remain very still underwater.

"They're pretty well camouflaged underwater as well, and they just stay underwater until that danger passes.

"We know that they can stay underwater at least about 20 minutes, but probably longer."

Swierk's research suggests the bubble is less an evolutionary accident or byproduct of being underwater, but instead a functional part of respiration.

The air bubble sticks to the lizard's scales because its skin is hydrophobic, meaning it repels water.

"Typically, that allows air to stick very tightly to the skin and permits this bubble to form," said Swierk.

"But when you cover the skin with an emollient, air no longer sticks to the skin surface, so the bubbles can't form."

Lizards covered with an emollient, a cream or gel-like substance that covers the skin's hydrophobic abilities, could not stay underwater as long without their air bubbles.

Swierk found that the lizards without the emollient could stay underwater 32 per cent longer than those with impaired bubble formation.

"This is really significant because this is the first experiment that truly shows adaptive significance of bubbles," added Swierk.

"Rebreathing bubbles allow lizards to stay underwater longer.

"Before, we suspected it - we saw a pattern - but we didn't actually test if it served a functional role."