Answer:
I believe you just answered it yourself. they development an immunity to insecticides the more they are exposed to it.
Some of the main functions of skin cells are to provide protection, perceive and transmit sensation, control evaporation and regulate temperature.<span> Skin cells, which are epithelial cells, are also self-repairing and reproduce quickly.</span>
Cartilaginous fish do not contain any bones - their skeleton is made up of cartilage.
