Page 92 - Engineering in Nature

Engineering in Nature

THE HEAT DETECTION SYSTEM IN SNAKES
The facial cavities
on the front of the
rattlesnake's head
contains heat sensors
that the snake uses to
detect infrared rays
given off in the form

of body heat by
warm-blooded birds
and mammals
nearby. Those sen-

sors are so sensitive that they can identify an environmental tempera-
th
th
ture rise of 1/300 of a degree, in just 35/000 of a second. The rattler
can follow prey that has moved away from it simply by detecting the
heat given off by its footprints.
Nor does its sensitive heat-detection system serve only to find
prey. The snake is a cold-blooded reptile that can maintain its vital
functions only when the ambient temperature is higher than 30 de-
grees. For that reason, its heat sensors are a great help in finding
warm caves or tree trunks where the snake can hibernate over the
winter. Of the fourteen species of snake only two have heat sensors,
and there are differences in the sensors between these two species.
Vipers, for example, bear their sensors on the front of the head under
their eyes.

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