Biologists recorded sounds in six caves located near three different mountain ranges in the northeast.
The researchers analyzed 44 hours of recordings andfound that the most common sounds that fish made were clicks and a successive series of clicks. There were other types of communication, such as claps, sharp clicks and rumbles, but they were much less common. Therefore, the researchers focused only on the first two types of "words".
Scientists compared the acoustic parameters of sounds,such as the length of each click, the pitch, and the speed at which successive clicks were made. The study showed several significant differences between the caves. In Molino the clicks were relatively high, while in Subterrano they were deep and loud. Fish from the Pachon Cave made clicks 10 times faster than their counterparts, and in Tinaja they used longer sounds.
The researchers suggest that the formationaccents is associated with genetic adaptation, due to a slight change in the shape of the fish's head in response to the specifics of environmental conditions. According to the authors of the work, the further development of differences may lead to difficulties with communication, which will lead to the formation of separate species.
Mexican astyanaxes exist in twovarious forms: one of them with good eyesight lives in open rivers, and the second, a blind fish with a translucent body, lives in caves. Researchers believe that the development of the underground form began about 20 thousand years ago, when individual fish moved from rivers to caves.
Like many other fish, Astyanax usenoise to communicate. To do this, they make at least six different sounds. Previously, scientists have shown that the meaning of individual "words" has changed when the fish moved underground. For example, a particular form of sharp snap used by sighted fish in aggressive encounters is produced by their blind counterparts during feeding.
Cover photo: Clinton & Charles Robertson
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