A team of biologists from the University of Toronto (United States) has discovered that anole lizards (Anolis) have the ability to breathe underwater with the help of a bubble that adheres to their snouts. Additionally, the research results have been published in Current Biology .
These lizards belong to a very diverse group that inhabits the Caribbean, Central and South America. Thus, some anoles are found in streams, and these semi-aquatic species often dive underwater to escape predators. In fact, they can stay submerged for up to 18 minutes because they breathe air into a bubble that sticks to their skin, scientists conclude.
The researchers measured the amount of oxygen in the air in the bubbles and found that it decreased over time, which is why, according to the researchers, the lizards exhale and inhale the same air. They probably developed this way of breathing because the ability to stay underwater longer helps them avoid predators.
Investigation Development
The scientists analyzed six different species of semi-aquatic anole lizards, and concluded that they all possessed the rebreathing trait (even though some species were very distantly related). Furthermore, although rebreathing has been studied in some arthropods such as water beetles, lizards were not expected to have this trait due to physiological differences between vertebrates and arthropods.
On the other hand, according to the authors, this trait could have developed because the skin of anole lizards is hydrophobic (that is, it repels water). A characteristic that probably developed in anoles because it protects them from rain and parasites. Thus, underwater, air bubbles adhere to the skin and, as a result, the ability to use these bubbles to breathe was developed.
However, as the lead authors of the study point out, more research is still required to understand exactly how the process works. For now, the researchers suggest forming in which this rebreathing might work.
The simplest theory is that the air bubble works like a scuba tank, providing the lizard with a supply of air in addition to air in the lungs. This is what various aquatic arthropods do to extend the time they can remain submerged.
However, a more complex theory suggests that the rebreathing process could make it easier to use the air found in a lizard’s nasal passages, mouth and windpipe that it would not otherwise use for breathing.
