The five senses are pretty standard among living creatures. Some animals will have an extra sense thrown into the mix -- directional, barometric, fashion -- but five or six is generally the limit of mortal perceptions. Unless you're a snake. They can have up to nine senses that we know about. No, they can't see dead people or anything -- it's just that they double up on all of the basic ones. Snakes have two types of hearing, two types of smell, and two types of sight.
"And 12 types of kickass."
A snake's jaw is linked directly to its inner ear, allowing it to literally hear surface vibrations. Snake jawbones are so sensitive that a horned desert viper can accurately strike at a small, quiet mouse coming up behind him ... in the middle of a pitch-black night. Further, their lower jawbones are separated into two halves, and the difference in timing between the vibrations received by the two sides informs the snake of the direction of its scampering prey. Snakes have high-fidelity directional hearing in their mouths.
Better yet, because snakes "smell" by "tasting" the air with their tongues, and because those tongues are typically forked, they also have incredible directional smelling. Snakes effectively smell in stereo. Finally, many varieties of snake have heat-sensing pit organs that can detect infrared light. For their relatively tiny size, these sensors are up to 10 times more sensitive than anything our technology has managed to create, and they come in several different types that all focus on different wavelengths.
Sichert, Andreas, et al.
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