Q: Can a hoop snake really put...

Q: Can a hoop snake really put its tail in its mouth and roll away from a predator?

A: The hoop snake is a myth, according to herpetologist George R. Zug of the Smithsonian Museum of Natural History. A snake might bite itself on the tail, he noted, “but I can’t conceive of any way that it could get itself upright and make itself rigid like a bicycle wheel,” he said.

Interestingly, however, a British researcher recently reported in Nature on a caterpillar that can do just that thing. Anatomist John Brackenbury of Cambridge University said that the larva of Pleurotya ruralis has three ways of withdrawing from a threat. With a mild threat, it simply walks backward. With a greater threat, it moves backward like a wave, with only its front and rear legs. In the most dramatic escape, it releases all legs and rolls like a hoop. The momentum is sufficient to produce up to five complete rotations, and the speed of about 39 centimeters per second is 40 times the normal walking speed.