While they may be visually similar, squid and octopi are quite different from one another. They live different lives and have varied body structures. They are both quite remarkable animals to study.

That being said, these aquatic animals also share numerous features, such as the ability to produce ink, change colors, use their tentacles for hunting, and use their beaks for breaking up their food into chunks. 

Both creatures hold a special place in mythological history, appearing in numerous stories and myths throughout history, including in tales of the Kraken and of the Gorgon of Ancient Greece. 

Squid (left) vs. Octopus (right) – a visual comparison

The Main Differences Between a Squid and an Octopus

Here are the top six key differences between a squid and an octopus: 

  • Physical Characteristics: Squid have tubular bodies with ten tentacles, and a triangular head, as opposed to octopuses with a more rounded head and eight tentacles. 
  • Catching prey: Squid uses two of their longer tentacles, a kind of specialized arm, to catch prey, whilst octopuses can use all of their arms to find prey. Squids also usually travel in large groups.
  • Swim: Squid swims through the water backward. Octopuses do this too but also tend to use two tentacles to walk along the seafloor (as their arms are more flexible).
  • Size: Squid is generally bigger than octopi.
  • Intelligence: Squid is thought to be less intelligent than octopi, although they are still both intelligent animals.
  • Habitat: Squid tend to prefer the open ocean to live in, whilst octopuses prefer seafloor dens as their home.

We’ll explore these differences and interesting facts about each ocean creature more below.

What is a Squid? 

The term “squid” is used to describe a type of soft-bodied mollusk. They are cephalopods of the Decapodiformes superorder. Squids are known for their rapid swimming ability, use of jet propulsion, and ability to actively hunt prey. They are also quite intelligent. Their natural predators include sharks, seabirds, sperm whales, and seals. 

They are consumed by people around the world and are particularly valued in Japanese commercial fisheries and in the Mediterranean.

A squid in blue water
A squid in blue water

Squid Appearance 

Squids have elongated tubular bodies, unlike most octopi, and shorter heads. There are eyes on either side and ten arms, and an internal skeleton. Two of which are feeding tentacles and are longer and slimmer than the other eight. There have been examples in which a squid while using its feeding tentacles, has been able to strangle a shark. 

Squid range in length from two inches long all the way up to an incredible sixty-five feet in length. They use their beak in order to eat the prey they catch, tearing it up into smaller bites and making it easier to consume. 

Squid have the remarkable ability to change color in order to signal and camouflage themselves. Their active camouflage allows them to match backgrounds to protect themselves against predators. Their skin is covered by chromatophores that they can control, creating different colors. Some, like the firefly squid, can use light to create countershading, allowing their undersides to appear lighter than their uppersides. 

Squid swim through the water backward, propelling themselves with the water itself. They also, like fish, use their gills for breathing underwater. Interesting, squid also has three hearts. It’s believed that the giant squid has the largest eyes of any animal. 

Squid Habitat, Diet, and Mating Practices 

Squid are found in marine environments all over the world, but not all species live all over the world. Some prefer warmer or colder environments. They feed on a variety of sea creatures, including other squids, shrimp, and other crustaceans, as well as fish. They can use their feeding tentacles to grasp and kill prey. 

One of the best-known abilities in a squid’s repertoire is the ability to produce ink. Their ink glands eject a cloud of ink, allowing them to distract and escape from predators. The ink itself is made of melanin particles. Squid ink is widely used as an ingredient in many cuisines, for example, with pasta or rice.

Squid mating practices are quite interesting. It takes place in open water. The male selects a female and transfers the spermatophores to her. Some squid, like the Caribbean reef squid, change colors during the courtship process. Others, like the female bobtail squid, eat the sperm packets of males that they’ve mated with, according to Monterey Bay Aquarium Research Institute. 

What is an Octopus? 

Octopi are soft-bodied mollusks, like squid. They belong to the order Octopoda. It is combined with the class Cephalopoda to which squid belongs. They are known for their long appendages or tentacles, two of which are used for walking along the seafloor. They come in a variety of shapes and sizes, meaning that their prey and natural predators vary. 

An octopus has eight legs, unlike a squid which has ten
An octopus has eight legs, unlike a squid which has ten

Octopus Appearance

The octopus, like the squid, has a beaked mouth and long tentacles. But octopuses have eight, whereas squid has a total of ten. Their soft bodies are easily malleable, allowing them to move through small gaps. They also move through the expulsion of jet water, like squid. Also, like squid, they are thought to be quite intelligent. The octopus has the interesting ability to walk on two rear appendages along the seafloor while the other six seek out food. Their beaks are located underwear their arms, and they’re used to tear up food into smaller bits and make it easier to consume. 

Their arms are also covered in sucker rings, circular in shape. It creates a seal when the rows of suckers are pressed against a surface. Their eyes are located at the top of their head. 

The largest known octopus species is the giant Pacific octopus that weighs in at around 33 pounds and with an arm span of fourteen feet. But, much larger specimens have been claimed to exist. They lack a skeletal structure, part of what allows them to squeeze through small spaces. Unlike squid, there are a wide variety of body shapes among octopi. Some are quite small and rounded, while others are longer and slimmer. For example, the Grimpothethis or dumbo octopus belongs to the former body shape category. 

Octopus Habitat, Diet, and Mating Practices 

Octopuses live throughout the ocean but prefer areas of coral reefs and among the seed. Some live in deeper areas of the ocean, including abyssal depths.

A solitary octopus in the dead dark sea
A solitary octopus in the dead dark sea

When reproducing, the male octopus uses one arm, known as a hectocotylus, to move the packets of sperm into the female’s mantle cavity. Like with squid, there are a few species that change color while undergoing the courtship and reproduction process. With the giant Pacific octopus, the female lays strings of eggs in a crevice and guards them for months, around a total of 160 days. 


What is the difference between an octopus and a squid? 

Octopi (plural for octopus) have more varied body shapes, are generally smaller, have eight arms, a flexible backbone, and rounded heads. Squid, on the other hand, have ten arms, two fins on top of their heat, and a rigid backbone. 

Is Calamari a squid or an octopus?

Calamari is squid but is often confused with octopus. The two animals are both eaten, although squid is more common. 

Which is bigger, squid or octopus?

Squid generally grow to be larger than octopi, between 60 centimeters to 20 meters long. Octopi, on the other hand, only reaches between one centimeter and nine meters long. 

What is the largest squid in the world?

The largest squid in the world is the giant squid which can grow up to forty-three feet or thirteen meters long. 

Who is smarter…squid or octopus?

Squid are generally believed to be the less intelligent of the two species. But that doesn’t mean that squid is unintelligent. The opposite is true, in fact. 

Do humans eat octopuses?

Yes, in many cultures and cuisines worldwide, octopuses are considered a delicacy. Along with the octopus meat and tentacles, humans consume octopus ink. It has been shown to have many benefits, such as anti-bacterial, anti-fungal, and anti-viral properties.

About Ocean Info

At Ocean Info, we dive deep into ocean-related topics such as sealife, exploration of the sea, rivers, areas of geographical importance, sailing, and more.

We achieve this by having the best team create content - this ranges from marine experts, trained scuba divers, marine-related enthusiasts, and more.

Sea Anemone with Clownfish

Dive into more, the ocean is more than just a surface view

Shrimp vs prawn: Main differences

Shrimp vs Prawn

While these two animals look similar, there are notable main differences between shrimp and prawns, from their appearance and taste to their habitat. Read on to learn more.

Share to...