What covers and protect arthropods bodies?

Answer 1

The exoskeleton covers and protects arthropods. It is mostly made of a tough protein called chitin, a long chain polymer comparable to cellulose. It fills the same role as the protein keratin in other animals, found in hair, nails, hooves, claws, beaks, etc. Some arthropods, like crustaceans, further harden their exoskeleton by biomineralization with calcium carbonate. Because it is inflexible, the organism has to periodically shed it in order to grow.

Answer 2

Arthropod skin or exoskeleton is made out of a tough protein called chitin, a long chain polymer glucose derivative chemically comparable to cellulose. Crustaceans further harden it through biomineralization with calcium carbonate. Because it is inflexible it needs to be replace periodically as the organism grows, through ecdysis (moulting).