Snakes known as pit vipers are the only vertebrates known with the ability to sense 1) infrared radiation. 2) ultraviolent radiation. 3) electromagnetic radiation. 4) visible light radiation. 5) none of these.

The correct answer is: 1) infrared radiation.

These venomous snakes also called crotaline snakes are distinguished by the presence of the structure pit, (or fossa), in the loreal area between the eye and the nostril on either side of the head with an organ within it. This organ is sensitive to infrared radiation, which enables them to detect and find prey on which they feed.

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