Squid vs. Octopus

Both squid and octopus are aquatic animals with eight long arms. In addition to their eight arms, squid also have two long tentacles. They also have two fins on their head, unlike the octopus. Whereas an octopus has no hard shell or bone in its body, squid have a stiff backbone-like structure called a pen.

A squid is any of a variety of cephalopod with a long, soft, thin body and 10 arms (eight shorter arms and two long tentacles) and two fins on its head. Squid vary in size from very small to over 65 feet in length. They prey upon fish and crustaceans. Some squid have the ability to emit an inky cloud as a defense mechanism. Their tentacles may have hooks, suckers, or sucker rings. They live in the open ocean.

An octopus is any of a variety of cephalopod with a round head, soft body and 8 strong tentacles, each with two rows of suckers. Octopi range from 1 cm to over 5 meters in length. They live on the sea floor and obtain food by piercing it and injecting it with venom.