Fish chatter with each other in order to stay together as a unit and better their chances of safety.
That was the finding by a team of researchers from the University of Auckland, which says it has found the first evidence of fish using communication calls for the purpose of maintaining cohesion of the overall group.
VIDEO: How Our Teeth Evolved From Ancient Fish
The researchers studied captive wild bigeyes (Pempheris adspersa), whose "pop" calls have been shown to max out at about 100 feet in range. They played two kinds of sound recording for the fish through underwater hydrophones. The first was of the normal ambient sounds of the reef tank where the fish were kept, while the second was of previously recorded bigeye vocalizations.
When the recordings were played, the fish grew five times more communicative with their calling rates, "talking" over the background sounds to stay in touch and swimming close together. But, when no sound recordings were played, the bigeyes swam farther apart.
These Fish Are Oddly Shaped For A Reason: Photos
The researchers note that while it was already known that fish use their contact calls for mating and for defense, it had yet to be clearly demonstrated that their vocalizations were also used to stay together as a group, something animals such as chimpanzees and elephants do.
"This study means that fish are now the oldest vertebrate group in which this behavior has been observed," said study lead Lucy van Oosterom, in a release, "and that has interesting implications for our understanding of evolutionary behavior among vertebrates."
The team's findings have been published in the journal Scientific Reports.