Difference between Octopus and Squid

Key Difference: Octopus and squid, both are aquatic animals belonging to the group of cephalopods. Cephalopod means feet around the head. They both share many common features. However, they also differ in many attributes like habitat, anatomy, lifespan, etc.

Octopus and squid, both are aquatic animals belonging to the group of cephalopods. Cephalopod means feet around the head. The body of these creatures consists of the head, the trunk and the neck connecting head with the trunk.

Octopuses belong to the family Octopodidae and group Octopoda. They can be commonly found in almost all seas. An octopus contains a large head with a strong beak and it has a small oval body. This body contains an internal shell but the fins are absent. An octopus is often recognized by its eight long slender arms.

They prefer to stay alone. It likes to hide in its den which it sometimes digs to occupy. There are many species of octopus and one can find the difference in arm’s length in different species.

There are many types of squids. They belong to the group Decapoda. They have a long and tapered body. They also possess a fin which is present on each side of its body. It has 8 muscular arms and 2 long tentacles. Both arms and tentacles bear suckers. They are widely distributed but they usually occur along shores, on high seas, and also from surface to even great depths.

Blood of both animals is blue in color due to the copper content which is found in oxygen carrying molecule. They also bear hard parrot type beaks which assists them in killing their prey. They both are generally not dangerous for humans. However, the blue ringed octopus produces enough poison which is capable of paralyzing a human being.

They differ in many aspects. Generally octopuses live in dens, whereas squids are commonly found in open seas. Octopus makes use of its eight sucker lined arms to get hold of its prey. On the other hand, squids use their eight arms lined with suckers and two tentacles to reach and capture their prey. They also differ in their diet. Octopuses eat bottom dwelling crustaceans, whereas, squids eat fishes and shrimps. Some scavenger squids may also be found in deep water.

Comparison between Octopus and Squid:

	Octopus	Squid
Classification	Phylum Mulusca, Order Octopoda, Superorder Octopodiformes, Kingdom Animalia	Phylum Mulusca, Order Teuthida, Superorder Decapodiformes, Kingdom Animalia.
Found in	Shallow coastal waters. However, some can be found at great depts too.	squids occur along shores, on high seas, and from the surface down to great depths.
Live in	Not in groups	May live in groups or alone
Example	Paroctopus bimaculatus., Octopus apollyoll	Lolqo peali, L.opalescens
Fins	Are generally absent in an adult octopus	Have 2 fins
Lifespan	1 to 3 years	9 months to 5 years
Body type	Rounded, have eight long arms, lack a shell. Bite the prey with a pair of break like jaws	Elongated, have eight arms and two tentacles , all armed with suckers. They also bear a greatly reduced shell.
Swimmers	Not better than squids	Better than octapus
Food	Bottom-dwelling crustaceans	Squids eat fishes and shrimps.
Attack on prey	They use piercing technique on the shells of the prey. Then they inject some poison which causes paralysis. Salivary enzymes released by them helps in getting the meet from the inner shell	They make use of their tentacles for holding their prey. They use beaks to tea the flesh apart and finally scrap the mean into their mouths.
Size	Ranges from 1 cm to 5 m in length	Ranges from 1 cm to 20 m in length