The basic squid has two fins, a mantle and a head with 8 arms and 2 tentacles each endowed with hooks or suckers rings. Some squid naturally lose the tentacles in post-larval stages, so that the adult possesses 8 arms only; some squid can have more than 2 fins. The suckers of squid are armed with hooks or sucker rings  or both. It is the squids' hooks and rings that have enthralled the watchers and animal lovers the most. Squid are mollusks like clams and oysters but they have no shells on the outside of their bodies! They have a shell inside their bodies called a pen.

There are about 375 species of squid. Squid range in size from under an inch to more than 60 feet in length! They have long, tubular bodies and little heads. Squid are very fast swimmers and use a kind of jet propulsion to move. Squid suck water into a long tube called a siphon and then push it back out with the aim in any direction. Squid have superb eyesight and may even be able differentiate the colour. The two tentacles are specially adapted for feeding and they use them to grab their prey. They have a sharp beak on their mouths which is used to break open the shells. Uniquely adapted squids they can change colours, using bio-luminescence to create light, shoot the ink.  Squids like to travel in groups and are found in sunlit zone or twilight zone.