What is a Squid?

Mary McMahon
Mary McMahon

Squid are ten-armed marine cephalopods that can be found in all the oceans of the world in a wide range of sizes, from extremely small to colossal. A large number of distinct families are found under the order Teuthoidea, which encompasses all animals known by this name. Thanks to their widespread distribution, they play a role in many cuisines, usually in the form of fried or sauteed dishes. They are also the subject of study by marine biologists.

Squid are marine animals that are found in oceans all over the world.
Squid are marine animals that are found in oceans all over the world.

Classically, the squid has an elongated body, marked at one end with two fins used to stabilize it while it swims. It has ten arms, including two longer tentacles that are used for grasping and manipulating food. The body is covered with a mantle, a flexible layer of tissue that protects the delicate inner organs. Inside the mantle is the pen of the squid, a hard protrusion that is all that remains of the creature's shelled ancestors.


Propulsion is the primary mode of movement for these animals. They push water through their central cavities to create a jet of water, and can move quite rapidly using this technique. Like their relatives the octopi, squid are extremely intelligent, and some species are capable of using logic on par with mammals on land. Both males and females also have an ink sac, which can be used to squirt ink as a defense measure, allowing the creature to escape from predators.

Fried calamari, made of squid.
Fried calamari, made of squid.

Like many animals that live in the ocean environment, some species are capable of withstanding immense pressure, and can be found quite deep in the ocean. Giant squid in particular stick to the depths of the ocean, and may live out their entire lives in the dark of the deepest areas. Some have been estimated to reach lengths of up to 80 feet (25 meters), although living specimens of that length are difficult to recover. Periodically, a giant squid washes ashore or is caught in a fishing net, offering biologists an opportunity to study it.

Squid have tens arms and belong to the cephalopod family.
Squid have tens arms and belong to the cephalopod family.

Squid are carnivores, and they are also highly sought after as a food source. Humans eat them in a wide variety of sizes, especially since every part of the animal except for the pen is edible. The flesh is slightly chewy and sweet, although it will be rubbery if it is prepared poorly. In nations that border the ocean, the creature is a common ingredient in an assortment of dishes, from calamari to Thai squid salad.

Both male and female squid have ink sacs, which are used defensively.
Both male and female squid have ink sacs, which are used defensively.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Aside from ink, squid also have a really cool defense technique called counter-illumination.

We learned some squid facts in class today. Apparently, squid have light emitting parts that they can turn on when there are predators. They do this to match the light coming in above the water so that predators will not be able to see their shadow. So they basically become invisible to predators.

Squid are really cool marine animals, one of the most interesting ones for sure.


@turkay1-- That's what I thought too until I had calamari at a restaurant one day. I didn't even know what it was when I ate it because my friend had ordered it. It looked like fries to me and smelled really good so I ate it. Then, my friend told me that it's made from squid. I couldn't believe it!

I know squid doesn't look appetizing raw, but when it's prepared well, it's really delicious. I think you should give it a try and then make up your mind about it.


I can't believe people eat this animal. It doesn't look tasty at all!


@hanley79 - Hi there. No, the rings in the calamari you ate weren't from the squid's tentacles. As you'll find out when you look up step by step instructions on how to prepare squid to eat, the rings are made from slicing up the length of the body. The body is hollow because, as you can read on WiseGEEK here, the squid has a central cavity to push water through in order to propel itself through the ocean. Hope this is helpful -- good luck preparing your first calamari recipe!


Hey, has anybody ever tried preparing calamari? I've really been wanting to try cooking some at home ever since I had this delicious calamari at a restaurant, and before I even look up squid cooking howto info, I figured I'd better research what kind of squid people usually eat.

Squid like Humboldt squid seem way too big to eat -- as aishia mentioned here, that kind gets to like six feet long. That's as big as a person! The calamari I ate had little round rings -- are those parts of the tentacles?


@gimbell - While I agree that washed up dead colossal squid or even Humboldt squid on the shores could set off some overactive sailors' imaginations and make them invent stories and drawings of tentacled sea beasts, I don't know if squid actually would have attacked boats like that.

I mean, I've heard about Humboldt squid attacks on documentaries, but that kind of squid only grows to around six feet long. The gigantic kind, like colossal squid, seem shy of the surface. The only footage of a live colossal squid so far was far below the surface, and they had to bait the squid into even coming within reach of the camera. I think if any tentacled creature actually attacked a boat in the past, it's more likely to have been a Pacific Giant Octopus or something. Squid are more aggressive, but they just don't come to the surface as much.


I think squid are some of the most fascinating animals in the world. Colossal squid washing up on the shores of beaches around the world are likely one of the reasons that stories of sea monsters got started.

Ever notice how most sea monsters in old pictures and stuff have giant tentacles that grab boats and pull them down? It could have been an octopus that inspired that imagery, but with their more aggressive behavior and "hunting tentacles", I'd be willing to bet the original inspiration was a squid of some kind. Colossal squid aren't really known to attack people, but there have been plenty of recorded attacks by swarms of Humboldt squid on fisherman and divers.

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