> To hunt at night, rattlesnakes use which kind of sense?And the answer: infrared vision.Snakes that are known as pit vipers, like rattlesnakes and moccasins, have thatdescription not because they live in pits, but because they have specialheat-sensing organs, located in pits between their eyes and nostrils. Thisallows them to notice a slight rise in temperature nearby.For predators whose primary prey are small, warm-blooded mammals, pit vipers areperhaps almost too evolutionarily prepared. These snakes are able to sensemovement and heat in complete darkness, and can strike their prey dead-onwithout a moment's hesitation. However, while scientists originally believed that these infrared pits weresolely for hunting, recent evidence points to its function as a means ofthermoregulation. In an experiment where scientists placed pit vipers and truevipers (snakes without infrared abilities) in a dark, warm maze, true vipersstruggled to find refuge while pit vipers had no problem. This suggests thatheat sensors help the pit vipers make decisions like seeking refuge, and fleeingprey. Now, scientists have begun to theorize that pit vipers' infrared visionoriginally evolved as a defense mechanism. Regardless of its evolutionary origins, pit vipers' infrared abilities combinedwith their deadly venom work to create some of the most dangerous predators inthe world. Check out this video to see the top cut of deadly snakes in action: