What this little lizard is wearing on its head may look like a silly hat at first glance, but it is actually its oxygen tank. By producing an air bubble on its snout, the Anolis aquaticus can stay underwater for up to 20 minutes without having to come to the surface for air.
This means that the anole lizard not only has an unusual trick, but one that is vital to survival, because it only dives when there is danger. And there are more than enough of them in its native Costa Rica. “Anole lizards are like the chicken nuggets of the forest. Birds eat them, snakes eat them,” explains Lindsey Swierk from Binghamton University in New York. If one of the many predators has its sights set on the small reptile, it simply jumps into the nearest body of water and stays underwater until the predator has gone away.
As Swierk discovered, the air bubble on the lizard’s head is even more relevant to this escape maneuver than previously thought. It was already known that the reptile gets oxygen from it, but experiments have now shown that it uses the air bubble in a similar way to how a scuba diver uses his mouthpiece: the anole lizard breathes out into the air bubble and then draws the air back in. From the outside, the air bubble on its snout rises and falls. Thanks to this ingenious trick, the little diving pro can stay underwater around a third longer than he would be able to without the air bubble.