What kind of radiation can a rattlesnake detect with its heat-sensing pit organs?

A rattlesnake can detect infrared radiation with its heat-sensing pit organs.

Rattlesnakes have a pair of facial pits between the eyes and nostrils. These specialized organs detect tiny differences in infrared radiation from warm objects, allowing the snake to sense the approximate direction and location of prey even in darkness.

The pits do not provide ordinary sight. Instead, their signals are processed alongside information from the eyes and other senses, giving the snake a thermal advantage during hunting. This system is especially useful for detecting warm-bodied mammals and birds.

Several other pit vipers also possess similar organs, as do certain boas and pythons. The ability is therefore not exclusive to rattlesnakes. It is also different from the vomeronasal system, which analyzes chemical particles delivered by the tongue.