The octopus is an invertebrate animal (it has no backbone) and belong to the phylum (group) Mollusca. Its closest relatives are the various species of squid and cuttlefish. Snails and slugs are distant relatives of the octopus. The common octopus has a relative called the giant octopus, whose tentacle span is up to 7metres! These huge creatures live in deep water along the northern Pacific coasts from the Sea of Japan east to Alaska and south to California.
The octopus lives in a hole or rock crevice in shallow water. Sometimes digs nest in gravel, or uses tentacles to construct a "fortress" out of rocks on the sea bed. These can often be identified by piles of discarded shells lying in the entrance.Read More: Food and Hunting