Turtle Talk: Exactly how do turtles communicate?
Turtles comprise one of the oldest living groups of reptiles, with hundreds of species found throughout the world. Many have been well-researched, and scientists know very specific things about their various evolutionary histories, metabolic rates, and the ways in which their sexes are determined. But there was one very obvious thing that has been largely left unknown by science until very recently. Turtles can make sounds.
Two new studies published recently in Chelonian Conservation and Biology and Herpetologica find that two turtle species vocalize when they reproduce and during some social interactions, and that their vocalizations are many and varied.
But why exactly did researchers go so long without discovering this aspect to turtle behavior? According to Richard Vogt, a herpetologist and turtle conservationist with the Brazilian Institute for Amazon Research and Director of the Center for Amazon Turtle Conservation, dogmatic assumptions are to blame.
"Because no one studied it, because some of the literature on reptiles published back in the 1950s claimed that turtles were deaf as a stump and did not vocalize, and everyone just believed [it] without investigating it," Vogt, who is a coauthor of both studies, told mongabay.com.
However, Vogt wasn't very surprised when he and his colleagues discovered that turtles were making sounds. He had long suspected this to be the case, but circumstance prevented him from studying it.
"While filming courtship behavior of false map turtles (Graptemys pseudogeographica) in captivity in the mid 1970s for part of my PhD thesis at the University of Wisconsin - Madison I noticed that the males were opening and closing their mouths while they were titillating the females with their vibrating foreclaws, and not trying to bite," Vogt said.
"At that time only the Navy had hydrophones and since the war protesters had blown up the army math research center at the UW. I did not think it a wise idea to be associated with the military, so my ideas laid fallow until 2005 when an inquisitive Australian student had access to underwater recording equipment and dropped a hydrophone in an aquarium with side necked turtles and found out they were vocalizing."
But Vogt held on to his curiosity, and later investigated the phenomenon with one of his students while studying turtles in the Amazon River. He attributes part of the reason for the knowledge lag about turtle vocalizations to technological limitations and the fact that the noises turtles produce are low and quiet.
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Turtle image via Shutterstock.