Snake Pits: Viper heat sensors locate cool spots

Researchers who glued minuscule plastic balls onto the faces of live rattlesnakes say the project has revealed the first experimental evidence of an overlooked role for the viper’s heat-sensing organs. The newly tested function: finding places for the desert snake to hide from the scorching sun.

HEAT SENSOR. A western diamondback rattlesnake lost its skill at spotting cool refuges when researchers blocked its heat-sensing pits with tiny balls and aluminum foil (below).