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11 animals that have a sixth sense

By: Bryan Nelson on Sept. 22, 2010, 1:20 p.m.
A green pit viper

Photo: Care_SMC/flickr

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Pit vipers

Venomous snakes of this family of are most easily identified by a pair of deep "pits" that can be found between the nostril and the eye. These pits are actually heat-sensing organs that allow the snakes to see in infrared — an invaluable sixth sense for a predator that often hunts at night.

The sense is so sensitive that pit vipers can accurately judge the distance and size of their prey even when their other senses are deprived.