In 2021, assistant research professor Lindsey Swierk from Binghamton University in New York and her team, discovered a new type of semi-aquatic anoles lizard. The lizards can stay underwater for at least twenty minutes by using an air bubble.

Researchers documented rebreathing for the first time in several species of Anolis Lizards, such as the water anole, anolis aquaticus, a semi-aquatic lizard that lives near streams in the forests of southern Costa Rica. Rebreathing allows air-breathing animals to inhale air that has previously been exhaled and take in additional oxygen.

Rebreathing is named after the scuba-diving breathing equipment. It is a unique skill shared by invertebrates, including species of spider and beetle, involving the use of bubbles of air, which cover the nose to increase the amount of time they are able to spend underwater.

This is the first time this behaviour has been documented amongst lizards, with researchers believing that the lizards use rebreathing as a defence mechanism.

According to Swierk, “Anoles are kind of like the chicken nuggets of the forest. Birds eat them, snakes eat them. So, by jumping in the water, they can escape a lot of their predators,”

“We know that they can stay underwater for at least about twenty minutes, but probably longer,” Said Swierk. Researchers questioned whether the bubble extended the water anoles’ ability to stay underwater and hide.

To test this, Swierk and the team applied a bubble impairing substance to the skin of one group of lizards.

“Lizard skin is hydrophobic. Typically, that allows air to stick very tightly to the skin and permits this bubble to form,” says Swierk, “But when you cover the skin with an emollient, air no longer sticks to the skin surface, so the bubbles can’t form.”

The team then measured how long the bubble impaired group was able to stay underwater compared to a control group of normal anoles. They found that the control group on average stayed underwater for 32% longer than the impaired group, with the findings showing the adaptive nature of the anoles and the importance of the bubbles they used.

According to Swierk, “This is significant because this is the first experiment that truly shows adaptive significance of bubbles. 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.”