For the three-toed sloth, a trip to the restroom is no rest at all. It’s a long, slow descent into mortal danger from the safety of home among the upper branches of the forest.

But the harrowing, and excruciatingly slow trip may be key to staving off starvation.

“What is striking about this behavior is the vulnerability,” says Jonathan Pauli, CALS professor of forest and wildlife ecology, who studies the deliberate, molasses-slow animals in northeast Costa Rica. “It’s very dangerous. And the energy required is non-negligible for an animal that has such a restricted diet.” Read more.