SURVIVAL SKILLS SURPASS : MASTER GLOBAL ESSAY

 

'' Why this tiny lizard dives with a natural scuba tank '' : Water anoles, semiaquatic lizards that are shorter than a pencil, are highly sought after snacks among predators in Costa Rican and Panamanian rainforests.

Preyed upon by snakes, birds, small mammals and larger lizards, the anoles hide in vegetation along rocky banks of streams.

Faced with danger, a lizard dives into the water and produces a bubble behind its nostrils that allows it to remain submerged up to 20 minutes, and perhaps much longer.

Lindsey Swierk, a behavioral ecologist at Binghamton University in New York, worked with Luke Mahler and Chris Boccia at the University of Toronto and other researchers to document the scuba-diving prowess of water anoles. But the purpose of their underwater antics was unclear.

Dr. Swierk wasn't sure whether the adaptation was a function of survival or just a strange side effect of their hydrophobic skin. While water can stick to a lizard's skin, it's composition allows air bubbles to form around parts of its body.

But in findings published in the journal Biology Letters, Dr. Swierk found that the bubble allowed this lizard to stay underwater much longer than it otherwise could, supporting the theory that it evolved this ability to evade hungry predators.

Using an underwater camera, Dr. Swierk first viewed the bubble appearing and disappearing atop the anole's snout. The bubble, which forms mostly as a result of air stored in the lizard's lungs but also from air pockets on its water-repellent skin, centers over the snout so the animal can rebreathe air underwater.

Researchers allowed 28 lizards collected from a rainforest in southern Costa Rica. Half were smeared with body lotion [ a daily moisturizer from Honest Company, according to the study] so the respiration bubbles wouldn't stick to their skin.

The other half got a splash of water to keep their hydrophobic skin intact and allow for normal bubble formation.

Lizards with intact bubbles stayed underwater 32 percent longer than those with impaired bubble production. When the lizards weren't able rebreathe air in the bubble, they couldn't  remain submerged for nearly as long.

Still, scuba diving is a last resort. It's not something the species uses often, said Kurt Schwenk, an evolutionary biologist at the University of Connecticut who was not involved in the study.

Water anoles are cold-blooded and regulate their temperature based on their environment. When diving into a cool stream, it takes them time to warm back up.

While this is the first vertebrate species to produce bubbles for underwater respiration, it's behavior that's found in aquatic insects like alkali flies and diving beetles, and in some arachnids.

The World Students Society thanks Sara Novak.