Piggyback rides and other crocodile fun

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“There is a lady who has a few pet crocodiles and they play tug-of-war,” says Vladimir Dinets of the University of Tennessee in Knoxville. This is bath time merriment, with crocs pulling on towels.

That’s just some of the fun Dinets has heard about since he published “Play behavior in crocodilians” in the February Animal Behavior and Cognition. He has encountered skepticism as well. “If you see a kitten playing with a ball, everybody will say it’s play,” he says. “If you see a crocodile doing the same thing, it’s ‘attacking the ball.’ ”

Dinets recognizes play based on criteria laid out by Tennessee colleague Gordon Burghardt. The behavior must, among other things, be spontaneous and look rewarding for its own sake. And it must be exaggerated, incomplete or out of context compared with, say, a real killer lunge.

Also, “crocodiles don’t move unless they really want to,” Dinets says. “If the crocodile is doing something for no obvious reason, it’s probably something the crocodile enjoys.”

He diagnosed spontaneous fun in a pair of Cuban crocodiles that routinely gave each other piggyback rides around their pool. Likewise for crocs of two species half a world apart, both of which tossed, nipped at and even gave nose rides to bougainvillea flowers; Dinets speculates that the animals might be drawn to small pink objects.

Or not-so-small objects. Dinets notes a report of a croc tossing around the carcass of a young hippo for about 25 minutes. Even crocs play with food.

Dinets has witnessed the daily play — his word — of a man and the crocodile he rescued. The two became a tourist attraction in Costa Rica. “They would kiss and hug, and the crocodile would make mock charges trying to scare the guy from behind,” Dinets says. They romped for 20 years, and “the guy never got a scratch.”

Dinets proposes 17 examples of crocodile play, a staggering leap in the annals of reptile recreation; Burghardt’s 2005 tome on animal play had five. Burghardt proposes that animals with complex and flexible behavior (which of course crocodilians show) play a lot even if people don’t notice. So Dinets would like to look elsewhere for overlooked funsters, he says. “For example, great white sharks.”