For humans, living in a bubble is a figurative coping mechanism. For water anoles, it is a literal description of an underwater survival strategy. The semi-aquatic lizards found in Costa Rica’s forests sometimes escape attackers by breathing a bubble over their heads that act as a scuba helmet when they dive and swim to safety, according to a report in Biology Letters.
Lindsey Swierk an assistant research professor of biological sciences at Binghamton University in New York, and an author of the study, had previously observed and documented this behavior. But she wasn’t sure to what extent, if any, the bubble played in helping the lizards stay underwater longer.
“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,” said Swierk in a press release. “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?”
Testing How Water Anoles Breath Underwater
To find out, Swierk and colleagues devised an experiment. They covered one group of the pencil-sized lizards’ skin with a substance that blocks bubble formation. They left another group of lizards’ skin untouched. Then they compared how long the two groups could remain underwater.
The untreated group could stay underwater about 32 percent longer than the group whose bubble-forming capacity was impaired.
“This is really significant because this is the first experiment that truly shows adaptive significance of bubbles,” Swierk said. “Before, we suspected it – we saw a pattern – but we didn’t actually test if it served a functional role.”
Read More: The Lizard That Walks on Air on Water
Anoles Unique Survival Strategies
Because anoles are the ‘chicken nuggets of the forest,’ according to Swiek, they need multiple ways to protect themselves from birds, snakes, and other predators. Their camouflaged skin helps them escape detection. Their narrow, lithe bodies help them slither away and hide in crevasses. And, as a last resort, they can seek underwater refuge for as long as 20 minutes.
Next, Swierk wants to determine whether the lizards are using the bubble as a “physical gill,” a mechanism some insects use when diving. That mechanism allows them to breath in the oxygen that diffuses in the water — not just the air trapped in the bubble.
Swiek suspects anoles do this too, because the bubble tank alone doesn’t appear to hold enough air for them to stay under water as long as they do. Siek’s group is testing that hypothesis by changing the level of oxygenation in water and, once again, measuring how it affects their dive time.
Studying how the anoles’ skin produces the bubbles could also serve as inspiration for man-made materials that mimic that ability.
Read More: 4 Ways Animals Adapt To Life In The Rainforest
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Before joining Discover Magazine, Paul spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
