a picture of lizard

Some tiny lizards have discovered a new ability. Underwater, they can rebreathe exhaled air. They do this, according to recent research, by trapping air on the snouts in bubbles.

Saving Air for Later

“When they are threatened, they dive underwater, detected by one of these lizards. They may also stay for a longer duration — for up to 18 minutes,” according to Chris Boccia. However, it remained a mystery how they could stay underwater without air for so long.

Boccia is a Ph.D. student at Kingston, Ontario, Canada, at Queens University. However, five years ago, at Canada’s University of Toronto, he was a master’s student in evolutionary biology. The anecdote was relayed to Luke Mahler, his then lecturer.

In 2009, Mahler was investigating an endangered species of Anolis lizard in the Caribbean country of Haiti. He observed something strange after releasing a lizard into a clean, shallow stream. As the lizard clung to the rough bottom, it released an air bubble around its nose. Then it appeared to suck the air in and out of that bubble repeatedly. 

Mahler had to go on to his following study location so that he couldn’t investigate anymore. Years later, though, he recalled the air-headed reptile. Boccia agreed to look into its actions. 

Bubble-Breathers

Boccia came to Costa Rica in 2017 in quest of bubble-breathing lizards. His crew and he went out at night to collect the lizards. “Doing this when they are asleep reduces stress for them,” he explains. It also makes it very much “easier for us to catch them,” he says. The crew gathered 120 lizards near streams and 180 lizards distant from streams while using headlamps to find them in the dark. The team included a variety of similar species. 

Without their tails, the animals grow to around 11 centimeters (4.5 inches) in length. Boccia’s party returned the lizards to their camp, where they put up river water containers. They then submerged each lizard in water. They held each other loosely so the creature might emerge whenever it pleased. 

Every lizard carried an air bubble around its snouts when they were overwhelmed. The bubble in and out seemed to breathe. Some lizards on the ground momentarily inhaled the bubble but did not repair much. Leurs relatives from the river rested more frequently and remained for longer durations underwater. “There went a lizard for 18 minutes,” remembers Boccia. “We started worrying about him.”

The lizards’ water-repellent skin might be a factor. A small layer of air may become stuck on the reptile’s skin when it dives into the water. Boccia believes that when the lizard exhales now, the air leaves through the nostrils and increases the trapped air layer. In this manner, the lizard could utilize its lungs to control the size of the bubble. 

However, if a lizard rebreathed the air in those bubbles, their oxygen levels should gradually decrease. Boccia took a small oxygen sensor with her and placed the thin wire-like gadget into the bubble surrounding the submerged lizards’ snouts to test this. 

“It required a lot of work, he adds, to avoid upsetting them. But his intuition was reinforced by this work. The oxygen in the blisters progressively reduced when the lizards were breathed.