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
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