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

Air bubbles extend the diving time

In a study led by Lindsey Swierk, an assistant professor of biological sciences at Binghamton University, 28 water anoles were observed to determine how long they could stay underwater with and without air bubbles. The results revealed that anoles with air bubbles could stay submerged 32% longer than those without. This extra time underwater helps them avoid predators in their natural habitats near river banks in Costa Rica and Panama.

How an air bubble works

Water anoles create a bubble by exhaling, which they then hold in place with their hydrophobic skin. As it dives, the bubble expands and contracts, allowing the lizard to redistribute oxygen, enabling longer dives. The longest recorded dive for an intact anole during the study lasted more than five minutes. However, anoles whose skin was treated to prevent blistering 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 time might have been more pronounced, as real predator pressure might have forced the lizards to stay submerged for even longer. The research team now aims to investigate whether the bubbles serve as “physical gills”, similar to how diving insects use trapped air to replenish their oxygen supply.