Snakes That Can See Without Eyes
by Andrew Durso
Pit vipers have an amazing and little-known ability to see infrared light. They do this by means of their eponymous pits, which are essentially a second pair of eyes located in the loreal region of their face, between the normal (visible light or “lateral”) eye and the nostril. Some snakes, such as Emerald Tree Boas (Corallus caninus), have up to forty pits, meaning that in effect they have forty-two ‘eyes’: two lateral eyes and forty infrared eyes.
Pit vipers have just two, but these organs are among the most exquisitely sensitive sensory organs in the animal kingdom. Other animals can also see wavelengths outside of the spectrum of light visible to humans. For example, bees and many birds can see ultraviolet wavelengths, and the complex eyes of mantis shrimp possess at least 16 different photoreceptor types, allowing them to see visible and ultraviolet light with fine sensitivity, as well as polarized light, thought to allows them to see their transparent prey…
(read more: Life is short, but snakes are long)