All forms of life have an instinctive urge to survive. Nature provides 31 with the means of survival. We have learned much about survival from 32 forms of animal life. Lizards, 33 can change the color of their skin and 34 the trees and leaves around them. 35 , they cannot be detected by other animals that threaten them. Nature provides other forms of protection 36 environmental dangers. Human beings, too, 37 special devices to protect 38 . Their skin is very 39 to temperature changes. 40 warm weather, sweating helps humans regulate their body temperature.
37