Difference between a Squid and an Octopus

Updated on March 22, 2017

Lurking beneath the ocean are two of the most intelligent invertebrates on earth. These are the squid and the octopus. They are both said to have impressive learning capabilities when it comes to adapting to their environment or surroundings. They are also known to employ awe-inspiring techniques when trying to catch their prey or trying to avoid a predator. How then can we distinguish a squid from an octopus? In this article, we’ll inform you about the differences between the two.


A squid

A squid is a cephalopod, which is a marine animal characterized by its bilateral body symmetry, a prominent head, a torpedo-like mantle and 8 arms. In addition to its 8 arms, the squid also has 2 tentacles. The squid belongs to the order Teuthida, which has more than 300 known species. The squid has fins, hooks and sucker rings. It also has an internal shell called a pen or gladii. Squids live in the open ocean either by themselves or in schools.


The majority of squids are less than 25 inches long. However, there are also giant squids which can reach up to 43 feet long. Cephalopods such as squids are noted to be masters of camouflage. Their skin changes color in order to adapt to their surroundings. There are tiny organs in their skin called chromatophores. These chromatophores are basically sacs filled with pigment. These sacs grow big when squids are threatened or when there’s a need to hide. When the muscles relax, then the sacs become small again. This trait gives them the ability to sneak up on their prey (usually shrimp and fish) as well as to protect themselves from predators since they don’t have protective outer shells. Squids, like most cephalopods, squirt ink or a dark pigment into the water as a means of escape. Some squids live up to 5 years.

Squids as food

One dish made from squid which is very popular in different countries is calamari. The squid is cut into rings, dipped in batter and deep fried. In other dishes, the body of the squid is sometimes stuffed whole or cut into pieces. Other parts of the squid are also eaten, including the ink. Only the beak and pen are removed. Squid is a good source of vitamin B12 and riboflavin.

An octopus

The octopus is also a member of the class Cephalopod. It belongs to the order Octopoda, which also has more than 300 species. An octopus has a rounded mantle, a beak, and 4 pairs of arms. It can regrow its arms when severed, leaving no permanent damage. It also has no internal or external skeleton which gives it the ability to squeeze into very tight spaces, provided its beak can fit through. An octopus usually lives in a den on the sea floor and tends to live alone.


This marine animal has 3 hearts and 9 brains. It has a central brain and one at the base of each arm. Studies have shown that octopuses are very smart and have good problem-solving skills. They can escape tanks and return to the ocean, open bottle lids from the outside and the inside, and make use of coconut husks and shells as tools. Apart from being able to perform these feats, they are noted to have a good memory. Octopuses are also extremely good at the art of camouflage. Their skin can change color as well as texture to blend in with the surroundings. They can also release ink and move quickly through the water. All octopuses have venom but only the blue-ringed octopus is identified to be deadly to humans. Octopuses usually have a short lifespan and live only up to 3 years.

Octopuses as food

The octopus is prepared in various ways, in many dishes, in different cultures. In some countries, it is eaten alive. However, this became a controversial practice since there is scientific evidence that the octopus can experience pain. One of the more popular ways of eating octopus is through Japanese cuisine. Takoyaki is a popular Japanese street food which contains octopus. They are ball-shaped snacks made of batter and minced or diced octopus along with other ingredients. The octopus is also a popular fish bait since the arms tend to move and wiggle even when already cut off.

Squid vs Octopus

What is the difference between a squid and an octopus?

A squid has a torpedo-shaped mantle, an internal shell, fins, hooks, and sucker rings while an octopus has a rounded mantle, no stiff bones or shell, and no fins, hooks, or sucker rings. Squids usually live in the open ocean by themselves or may live in schools. Octopuses, on the other hand, are solitary animals which mainly live in dens, usually on the sea floor. Squids mostly feed on shrimp and fish and use their tentacles to capture their prey. octopuses, on the other hand, feed on bottom-dwelling crustaceans. They use their arms then pierce the shell of their prey and inject poison to paralyze them. In terms of lifespan, squids live longer and can live up to 5 years compared to octopuses which only live up to 3 years.

Comparison Chart

Squid Octopus
Mantle is torpedo-shapedMantle is rounded in shape
Has an internal shell called a pen or gladiiNo stiff bones or shell in their body
Equipped with 2 fins, hooks, and sucker ringsNo fins, hooks, or sucker rings
Lives in the open oceanLives in a den on the sea floor
Some are solitary creatures but they may also live in schoolsAlways lives alone
Uses tentacles to capture preyUses arms to capture prey, pierce their shell, and inject poison to paralyze them
Feeds on shrimp and fishFeeds on bottom-dwelling crustaceans
Has a longer lifespan – up to 5 yearsShorter life span – up to 3 years


Watch this video to see the main differences between a squid and an octopus.