How is the frog skin different from human skin

Frog skin has like slimy stuff on the outside

Frog skin is the way frogs exchange a lot of materials with their environment. It is very permeable. Many frogs don't drink because they can absorb / excrete water through their skin.

Human skin is not easily permeable. It is a barrier that protects us. It can't absorb water. It has sweat pores that excrete water to cool you off. It is continously shedding dead cells and replenishing them with new ones. Melanin darkens your skin to protect from sun exposure. 

Where’s the selection?