Diving lizards use air bubbles to breathe underwater

Semi-aquatic lizards, such as the water anole (Anolis aquaticus), have a unique ability to remain underwater for extended periods of time by creating an air bubble around their snout. This behavior, first observed in 2018, has now been confirmed in 18 other anole species. The air bubble helps the lizards breathe underwater, allowing them to remain hidden from predators for longer periods of time. Researchers recently discovered that this bubble is not just a side effect of their water-repellent skin, but plays a vital role in their survival.

Air bubbles extend dive times

In a study led by Lindsey Swierk, assistant research professor of biological sciences at Binghamton University, 28 water anoles were observed to determine how long they could stay underwater with and without their air bubble. The results showed that anoles with the air bubble could stay underwater 32 percent longer than those without. This extra time underwater helps them avoid predators in their natural habitats along riverbanks in Costa Rica and Panama.

How the bubble works

Water anoles produce the bubble by exhaling, which is then held in place by their hydrophobic skin. As they dive, the bubble expands and contracts, allowing the lizard to redistribute oxygen, allowing for longer dives. The longest recorded dive for an unmodified anole during the study lasted more than five minutes. However, anoles whose skins had been treated to prevent the formation of the bubble had shorter dive times.

Future research on bubble breathing

Swierk suggests that if the study had been conducted in the wild, the difference in dive times might have been greater, as pressure from real predators might encourage the lizards to stay underwater even longer. The research team now wants to investigate whether the bubbles act as a “physical gill,” similar to how diving beetles use captured air to replenish their oxygen supply.