Answer :

Snails are invertebrates because they have exoskeletons. The shell is the exoskeleton. Animals which have an internal skeleton with a backbone are called vertebrates. For example, Humans are vertebrates.          

Hope it helps         

is an invertebrate because is a mollusk, and mollusks doesn´t have vertebraes, another examples of mollusks would be clams, slums, mussels and oysters any of them has vertebraes