Question

why reptiles have dry and scaly skin?

Answer 1

Reptiles have dry, scaly skin. But they don't need moisturizer! Their special covering actually helps them hold in moisture and lets them live in dry places.
Reptile scales are not separate, detachable structures -- like fish scales. Instead, they are connected in a "sheet," which is the outermost layer of skin. Every so often, this layer of skin is shed and replaced. In some reptiles the skin flakes off in chunks. In snakes, the skin is usually shed in one piece.
What about turtles and tortoises? You may not think of their shells as being scaly, but they are! They are complex structures made up of bones and scales that develop from the outer layer of skin. It's natural body armor!