The word Invertebrate describes any
animal which does not have a spine. Although lacking an internal
skeleton, many invertebrates make up for this by developing a shell
(as with snails), or a hard exoskeleton that protects their entire
body (as with lobsters and insects.) Having a shell doesn't qualify
an animal as an invertebrate, however; many invertebrates are soft-bodied,
relying on other ways to protect themselves from their environment. Click here for more info...