But does Kryptonite make them weak?

This is just bizarre:

Squirrels Use Heat to Threaten Snakes

California ground squirrels look like cuddly, defenseless things. But faced with hungry rattlesnakes, they broadcast red-hot ire to the enemy by heating up their tails. The behavior, reported at a meeting of the Animal Behavior Society in Oaxaca, Mexico, is the first deliberate animal signal known to be communicated via heat.

In the study, Aaron Rundus of the University of California, Davis, put adult squirrels in cages with snakes and filmed the face-off with a heat-sensitive infrared camera. When up against a rattlesnake, the squirrels lashed their tails back and forth, held their tail hairs on end, and emitted a distinct heat glow from their posterior appendage. But the squirrels mustered no such heat response when paired with a gopher snake.

Rundus said the squirrels are warning rattlers in a language the snake can understand. Rattlesnakes use heat sensitive organs on their snouts known as pits to home in on prey. The squirrels can differentiate between enemies and react accordingly, Rundus said, possibly to distract the snakes from more vulnerable young.