Emily Chan
Reptiles are extraordinary creatures with diverse abilities. For example, tiny lizards in Costa Rica’s rainforest have developed a way to “scuba-dive” by creating air bubbles on their foreheads to breathe underwater, allowing them to stay submerged for long periods of time. This unusual behavior could help them hide from predators on land.
The first case of a semi-aquatic lizard known as a stream anole (Anolis oxylophus) breathing underwater was caught on camera in 2018. The footage showed the lizard using a bubble of stored oxygen that surrounded its snout.
The ability had never been seen in lizards before. Since then, at least 18 other species of anole have been found to form air bubbles, too.
Until now, scientists weren’t sure if the bubble enabled the lizards to stay underwater for a prolonged period of time or if it formed as a result of their water-repelling skin.
In a new study, a team of researchers tested almost 30 water anoles and discovered that those using air bubbles remained underwater 32 percent longer than anoles without bubbles. The extra time likely helps them escape predators.
“There are a lot of threats in their environment, and it makes sense that they would evolve a unique way of dealing with them using the resource—water—that they have available,” said Lindsey Swierk, a co-author of the study and an assistant research professor in biological sciences at Binghamton University in New York.
Most of the time, semi-aquatic water anoles sit on boulders near riverbanks in the forests of Costa Rica and Panama. These lizards grow up to eight inches long. When they feel threatened, they will jump into the water to escape. They can stay underwater for at least about 20 minutes, possibly even longer.
The anoles exhale to create a bubble that surrounds their head. The bubble stays in place because of the lizards’ water-repelling skin. The bubble expands and collapses as the anoles exhale and inhale.
The researchers suggest this redistributes the air on and inside an anole’s body, providing it with enough oxygen to make long dives.
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