How is a vertebrates skeleton similar to a arthropod?

exoskeleton
Arthropods have a skeleton on the outside, called an exoskeleton. (By contrast, vertebrates will have an internal skeleton or endoskeleton). The exoskeleton of arthropoda is 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 where it would be found in hair, nails, hooves, claws, beaks, etc. Some arthropods, like crustaceans, further harden their chitin exoskeleton by biomineralization with calcium carbonate. Because it is inflexible, the organism has to periodically shed it (moult) in order to grow, a process called ecdysis.