Crocodiles just wanna have fun? Researchers found these cold-eyed reptiles actually exhibit some shockingly human-like traits.

Researchers observed crocodiles surfing waves, playing with balls, giving each other piggy-back rides, the University of Tennessee reported.

Vladimir Dinets, a research assistant professor in psychology, collected data of crocodilian-themed groups on social media and through various conferences. The findings revealed that crocodilians engage in all three main types of play distinguished by behavior specialists. These categories include: "locomotor play, play with objects and social play."

The most common type of play observed in the crocodiles involved objects such as wooden balls, streams of water and floating debris. They were also observed to participate in locomotive play in young alligators, which included behaviors such as sliding down ropes and surfing ocean waves. An example of observed social play included baby alligators riding on older friends' backs.

Crocodiles have also been known to play with other animals, such as river otters. In rare cases crocodilians have even been known to form bonds with humans that have been their playmates for years.

One example of this fascinating phenomenon was seen in a crocodile that was rescued by a man after being shot in the head, the two became great friends and played together every day for 20 years.

"The croc would swim with his human friend, try to startle him by suddenly pretending to attack him or by sneaking up on him from behind, and accept being caressed, hugged, rotated in the water and kissed on the snout," Dinets said.

The findings were made possible by past work from Gordon Burghardt, a professor in the Department of Psychology and the Department of Ecology and Evolutionary Biology, which defined "play" in a new way that allowed it to be applied to critters previously believed to be incapable of it. The recent findings could provide insight into how intelligence evolves and what factors play into this type of development.

"Hundreds of thousands of crocodilians are now kept in captivity in zoos, commercial farms and breeding centers set up for endangered species. Providing them with toys and other opportunities for play makes them happier and healthier," Dinets said.

The findings were published in a recent edition of the journal Animal Behavior.

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