Crustaceans, such as crabs and lobsters, are the primary diet of the
octopus. Squid have more of a tendency to stick to more immediate family
such as clams, snails, and sometimes octopus. Gives a whole new sense to
the phrase "Keeping it in the family".
Cartilage, which is also found in squid and octopus, is a type of
protein which is a natural polymer.
Protein looks like this:
Cartilage is found in all living things,
including sharks. It is also found in your bones
and hair.
Octopus live around caves, which are made of stone (not a polymer) and
some smaller species can be found among coral
reefs. Squid are mainly in the deeper parts of the
ocean, and are very rarely seen. Sometimes they can be found in the
belly of sperm whales, which quite honestly is
a place that I would not want to be.