Study confirms that nose bubbles allow anoles to breathe underwater
The anole lizard may be a popular pet, but here's something that not many people may know: some of the things can breathe while underwater. A new study has confirmed their ability to do so, and explains what makes it possible.
First of all, anoles have hydrophobic skin, meaning that it repels water. In everyday life, this likely helps protect them from rain and parasites. In certain semi-aquatic types of anoles, however, it also allows an exhaled air bubble to cling to the skin above their nostrils when they go underwater.
Led by University of Toronto biologist Chris Boccia, a team of scientists recently verified that the lizards are able to breathe oxygen from within that bubble, staying submerged for up to 18 minutes at a time. Known as "rebreathing," this capability allows them to escape from land-based predators.
The behaviour was studied in six semi-aquatic anole species – that aren't particularly closely related – living in Costa Rica, Colombia and Mexico. Scientists had observed the phenomenon as far back as 2009, although at that time it couldn't be investigated further. In fact, no other vertebrate has ever been known to rebreathe – it has previously been seen mainly in aquatic arthropods such as water beetles.
Boccia and colleagues confirmed that breathing was taking place based on the fact that the oxygen content of the anoles' air bubbles steadily decreased the longer they remained submerged. It is additionally suggested that exhaled carbon dioxide may be dispersed from the bubble and into the surrounding water, keeping it from being breathed back in.
And although more research is required, it's even possible that the bubble may act like a gill, absorbing oxygen from the water. Both the CO2 dispersion and the oxygen absorption have already been documented in water beetles' air bubbles.
"It’s too early to tell if lizard rebreathing will lead to any particular human innovations," says Boccia. "But biomimicry of rebreathing may be an interesting proposition for several fields – including scuba-diving rebreathing technology, which motivated our naming of this phenomenon."
The research is described in a paper that was recently published in the journal Current Biology.
Source: University of Toronto