Smart lizards have a trick to breathe underwater for a longer duration

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Smart lizards have a trick to breathe underwater for a longer duration

Terrestrial creatures can’t utilize or live in the aquatic environment because of their inability to breathe underwater. There are some creatures like the frog, who can live both on land and water, as they can breathe inside water. Christopher K. Boccia and his team observed some air-breathing anoles underwater, who can survive for longer durations when hiding from predators or danger. To explore how Anoles can survive underwater, they conducted a study, published in Current Biology. They found re-breathing as their main source of extended breathing underwater.

Lizards can dive in the water if they feel threatened and can withstand extreme hypoxia before resurfacing if the predator is still there. Anoles however can remain for astonishingly 18 minutes underwater, and that has puzzled many biologists. But finding the evidence of water anoles can breathe underwater wasn’t a part of the main research plan and was only serendipitous explained Lindsey Swierk from Binghamton University, that how long diving duration of anole gave her the itch to look closer by an underwater camera. That is when she saw a shining snout of the submerged anole and filmed it.

Pakistan Journal of Biological Sciences

The reason behind the snout formation is that anoles are semi-aquatic and when they exhale air it clings to their skin like a bubble and they can then re-inhale the same air, this ploy is known as ‘rebreathing’. By re-breathing, small, slow anoles can have a great advantage over predators, as they can hide underwater, which makes them very hard, if not impossible to spot. When these water-repelling scales, with petite, portable air pocketswere measured for oxygen levels, they seem to lose air content with time, which ascertains the belief that anoles are using this method for breathing underwater.

These sustained rebreathing features were observed in only 5 groups of anoles that are all semi-aquatic species, however, non-aquatic anole species only appear to have rudimentary bubble-breathing skills.Other diving insects like river bugs and spiders also have been found re-breathing using air bubbles underwater. Spiders are known to have abdominal buddle inside to let thin underwater. Vertebrates however because of their large size and surface area to body ratio require more oxygen to survive with a huge metabolic rate, which limits their ability to survive underwater.

Researchers believe that the scuba bubble of anole can have many advantages, it can let the anole redirect the oxygen-filled air from ‘dead space’ to inside of its body, just like nose and mouth cavity, towards lungs or from plastron. Similarly, this bubble can allow them to eliminate excess carbon dioxide. While another speculation is that anole might be using the bubble to pull in oxygen from water via diffusion. Many researchers believe that this bubble-breathing attitude helps the anoles and other aquatic species to have improved visual hunt.

This sustained rebreathing by semi-aquatic anoles is pointing towards the repeatability of evolution, all the semi-aquatic anoles there were studied by these researchers showed sustained re-breathing, suggesting a high degree of predictability in anole adaptation.

Keywords:

Convergent evolution, adaption, expectation, respiration, behavior, semi-aquatic lizard, hydrophobic skin, plastron, anoles.

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