Amphibians come out of the water when they learn to swim

A curious theory has recently been advanced: an evolutionary feature that could have allowed the first amphibians to survive on land could be linked to the ability to blink. These are the conclusions of research published in the journal Proceedings of the National Academy of Sciences. The study was developed by scientists at Penn State University and Seton Hill University.

Coordinating expert group Thomas Stewart And Brett AielloStudy samples from Periophthalmodon Septemradiatusalso known as mud bouncyIt is a type of fish found in marine, brackish and fresh watersIndia inIndonesia. Experts believe that these animals spend most of their day outside the water. They also developed the ability to close and open their eyelids.

Amphibian specificity

This evolutionary feature, according to the researchers, unites a whole group of quadrupeds, or the group of mammals, birds, reptiles and amphibians that took their first steps on land about 375 million years ago. “eyelash – explained Stewart – It is important for many reasons, for example it keeps the eyes moist, clean and protects them injuries, and at the same time they are useful for communication purposes. Understanding how this behavior evolves can be challenging, because anatomical changes That allow the eyelids to close mainly relate to soft tissues, which are not preserved in the fossil record“.

the Septimradiatus, which independently initiated the development of this behaviour, could be considered as a study subject to examine these mechanisms. Scientists analyzed videos of mud bouncy, by comparing their positions with those observed in related but incapable of blinking species. eyes mud bouncy They protrude from the top of the head, like frogs.

What happens when these amphibians blink

When blinking, the fish momentarily retracts its eyes into the sockets, where there is an elastic membrane. “This feature – announced ELO – It appears to have evolved through a rearrangement of existing muscles that favored the formation of this elastic tissue. Our work indicates that, just like us, me Septimradiatus They blink frequently when their eyes are dry. The curious aspect is that these animals do not have glands or tear ducts, but the eyelashes seem to be able to protect the eyeballs from possible injuries and from foreign bodies entering the eye.“.

In the quadrupedsAs the scholars noted,Closing and opening of the eyes is an involuntary yet complex and fascinating action, linked to multiple functions, and essential to the health and well-being of the eyes.”our work – He finished Stewart – Indicates that the cover-closing behavior in the mud bouncy It evolved independently from the first amphibians to land. However, since this trait appears to be related to the same functions, we hypothesize that it is related to the set of characteristics that have evolved in connection with adaptations from aquatic to terrestrial life“.