The nictitating membrane's function is to provide the eye with a special extra level of safety while the creature is still able to see.
Natural? I know that it has 4 factors -<span>Variation. Organisms (within populations) exhibit individual variation in appearance and behavior. ... <span>Inheritance. Some traits are consistently passed on from parent to offspring. ... </span><span>High rate of population growth. ... </span><span>Differential survival and reproduction.</span></span>
Answer: The receptors are highly specific.
Explanation: yes