We've seen animals such as dogs and dolphins play for fun, but new research suggests fish can have a good time too.
A research team was the first to document "play" behavior in a member of the cichlida fish species, a group that includes tilapia, the University of Tennessee reported.
"Play is repeated behavior that is incompletely functional in the context or at the age in which it is performed and is initiated voluntarily when the animal or person is in a relaxed or low-stress setting," said Gordon Burghardt, a professor in the departments of Psychology and Ecology are Evolutionary Biology who has defined "play" in a way that has allowed him to observe the activity in creatures such as wasps and certain reptiles.
To make their findings the researchers studied and filmed three male fish individually over the course of two years. They observed these subjects repeatedly striking a bottom-weighted thermometer, even when there was no food or other fish present in the tank; this behavior satisfied the researchers' criteria for "play."
"The quick righting response seemed the primary stimulus factor that maintained the behavior," Burghardt said. "We have observed octopus doing this with balls by pulling them underwater and watching them pop back up again. This reactive feature is common in toys used for children and companion animals."
Burghardt believes humans can gain insight into themselves by correctly defining "play" and observing it in animals generally thought to lack the capacity to do so. He claims play is embedded in species' biology and is part of their evolutionary history as opposed to just "random, meaningless" behavior.
"Play is an integral part of life and may make a life worth living," Burghardt concluded.
The findings were published in a recent edition of the journal Ethology.
