The above FLIR thermal imaging video of a cold-blooded snake striking a heated target is an example of how the snake perceives its prey in the environment. The ability to sense infrared thermal radiation evolved independently in several different families of snakes. Essentially, it allows these animals to “see” radiant heat at wavelengths between 5 and 30 μm to a degree of accuracy such that a blind rattlesnake can target vulnerable body parts of the prey at which it strikes. It was previously thought that the organs evolved primarily as prey detectors, but recent evidence suggests that it may also be used in thermoregulation and predator detection, making it a more general-purpose sensory organ for survival.
Using a special thermal camera, a National Geographic photo team captures the different body temperatures of men and women, most noticeably in their hands.
Degrees of Seperation
The old saying “cold hands, warm heart” may have some truth to it. University of Utah researchers found that though women’s core body temperature can run 0.4°F higher than men’s, women’s hands run 2.8°F colder—87.2°F on average, compared with 90°F for men.
“Blood vessels in the body’s extremities are the first to constrict when temperatures drop. The gender differences in such cold responses are still not completely understood, says Johns Hopkins University’s Fredrick Wigley, but hormone levels and muscle mass could play a role. Women are also up to five times as likely to have Raynaud’s, a disorder in which cold temperatures or even emotional stress can make blood vessels temporarily collapse. Fingers can turn white, blue, or red in even mildly cold situations, such as when opening a refrigerator.” — Eve Conant, National Geographic Contributor
VIDEOGRAPHY: Jason Kurtis
THERMAL IMAGING: Tyrone Turner
EDITOR: Spencer Millsap