In a new study, scientists found that bumblebees enjoy playing for fun’s sake, just like dogs and dolphins. The results come in the midst of a big news-making year for the bee, which has officially been designated a fish and capable of distinguishing between odd and even numbers.

The study, published in Animal Behavior, set up three different ball-rolling experiments to observe whether the bumblebees’ behavior meets University of Tennessee biopsychologist Gordon Burghardt’s five criteria for play. They are:

1. The behavior is not fully functional.
2. The behavior is voluntary, spontaneous, and pleasurable.
3. The behavior is markedly different than those used for finding food or a mate.
4. The behavior is repeated but not stereotyped.
5. The behavior occurs in a stress-free environment.

During the experiment, it was found that the bees intentionally went out of their way to roll the balls, without an incentive, with the younger bees “playing” more often than the older ones. This research builds upon other behavioral studies that food as a reward.

First, the bees were trained to find free-moving balls in two different colored chambers. The bees showed a preference for the chamber where they had played with the balls. In another, bees were given the choice to walk between either immobile or mobile balls and continuously engage with the mobile balls, without incentive, exhibiting spontaneous behavior.

Check out a video of the bees playing to see this adorable hypothesis in action.

This latest study concluded that bumblebees rolled wooden balls with no benefit other than the rewarding experience of play. The researchers plan further studies to investigate how animal play behavior impacts brain development.