Octopus vs. Squid — What's the Difference?
By Tayyaba Rehman — Updated on September 16, 2023
An octopus has a rounded body, eight arms, and no internal shell. A squid has a more streamlined body, ten limbs (two are longer tentacles), and a thin internal shell called a pen.
Difference Between Octopus and Squid
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Key Differences
Both octopuses and squids are cephalopods and live in marine environments, but their behavior and abilities vary. Octopuses are generally more flexible and are known for their problem-solving skills. Squids are generally faster swimmers, aided by their streamlined bodies and jet propulsion.
In terms of their physical structures, octopuses do not have an internal shell. Squids possess a thin, internal shell called a pen, which provides some structural support but is much less rigid than the shells of other mollusks.
From a grammatical standpoint, the plural of octopus is often debated: it's either "octopuses" or "octopi." Squid is both singular and plural. Both words usually function as nouns but can be used as adjectives in certain contexts, like "octopus ink" or "squid jet propulsion."
When it comes to their role in the food chain, octopuses are often predators but can also be prey. Squids serve similar roles but are also commonly found in human cuisine, often served as calamari.
Comparison Chart
Number of Limbs
8 arms
8 arms, 2 tentacles
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Body Shape
Sack-like
Streamlined
Internal Shell
None
Thin internal shell (pen)
Speed
Generally slower
Generally faster
Plural Form
Octopuses or Octopi
Squid (both singular and plural)
Compare with Definitions
Octopus
A cephalopod lacking an internal shell.
Unlike some mollusks, an octopus doesn't have an internal shell.
Squid
A cephalopod with a thin internal shell called a pen.
The squid's pen provides some structural support.
Octopus
Capable of emitting ink for defense.
The octopus squirted ink to escape from the predator.
Squid
Known for fast swimming through jet propulsion.
The squid uses jet propulsion to escape predators.
Octopus
Predator in marine ecosystems.
The octopus captured a crab for its meal.
Squid
Often served as food, known as calamari.
I ordered the fried squid, also known as calamari.
Octopus
Octopus (pl. octopuses, see below for variants) are soft-bodied, eight-limbed molluscs of the order Octopoda (, ok-TOP-ə-də).
Squid
Capable of emitting ink like an octopus.
The squid released a cloud of ink to confuse its attacker.
Octopus
Any of various carnivorous marine cephalopod mollusks chiefly of the family Octopodidae, having a soft body, eight arms with suckers, a large distinct head, and a mouth with a strong beak.
Squid
Squid are cephalopods in the superorder Decapodiformes with elongated bodies, large eyes, eight arms and two tentacles. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle.
Octopus
Something, such as a multinational corporation, that has many powerful, centrally controlled branches.
Squid
A device that measures minute changes in magnetic flux by means of one or more Josephson junctions, often used to detect extremely small changes in magnetic fields, electric currents, and voltages.
Octopus
Any of several marine molluscs of the family Octopodidae, having no internal or external protective shell or bone (unlike the nautilus, squid and cuttlefish) and eight arms each covered with suckers.
Squid
Any of various marine cephalopod mollusks of several families of the superorder Decapodiformes (or Decabrachia), having a usually elongated body, eight arms and two tentacles, a reduced or absent internal shell, and a pair of fins.
Octopus
(uncountable) The flesh of these marine molluscs eaten as food.
Squid
Any of several carnivorous marine cephalopod mollusks, of the order Teuthida, having a mantle, eight arms, and a pair of tentacles
Octopus
An organization that has many powerful branches controlled from the centre.
Squid
A fishhook with a piece of bright lead, bone, or other substance fastened on its shank to imitate a squid.
Octopus
To put (or attempt to put) one's fingers, hands or arms in many things or places at roughly the same time.
Squid
A sailor in the Navy.
Octopus
To spread out in long arms or legs in many directions.
Squid
A quid; one pound sterling.
Can you lend me five squid? I feel like a bacon sarnie.
Octopus
To plug a large number of devices into a single electric outlet.
Squid
A motorcyclist, especially a sport biker, characterized by reckless riding and lack of protective gear.
"In my mind, a street squid is anyone who races on the street. Period."1
"squid: a cocky motorcyclist who darts very aggressively through traffic"2
Octopus
(by extension) To grow in use vastly beyond what was originally intended.
Squid
(angling) To fish with the kind of hook called a squid.
Octopus
To hunt and catch octopuses.
Squid
(parachuting) To cause squidding an improper, partial, parachute inflation, that results in the sides of the parachute folding in on the center, and pulsating back and forth.
Octopus
To behave like an octopus.
Squid
Any one of numerous species of ten-armed cephalopods having a long, tapered body, and a caudal fin on each side; especially, any species of Loligo, Ommastrephes, and related genera. See Calamary, Decacerata, Dibranchiata.
Octopus
A genus of eight-armed cephalopods, including numerous species, some of them of large size. See Devilfish.
Squid
A fishhook with a piece of bright lead, bone, or other substance, fastened on its shank to imitate a squid.
Octopus
Any member of the genus Octopus.
Squid
(Italian cuisine) squid prepared as food
Octopus
Something resembling an octopus in having numerous controlling arms or branches that reach widely and influence many activities; - used mostly of organizations, such as diversified corporations.
Squid
Widely distributed fast-moving ten-armed cephalopod mollusk having a long tapered body with triangular tail fins
Octopus
Tentacles of octopus prepared as food
Squid
A marine animal with a streamlined body and ten limbs.
The squid darted away when it sensed danger.
Octopus
Bottom-living cephalopod having a soft oval body with eight long tentacles
Octopus
A marine animal with a sack-like body and eight arms.
The octopus camouflaged itself among the coral.
Octopus
Known for problem-solving and intelligence.
The octopus figured out how to open the jar to get the food.
Common Curiosities
How many limbs does a squid have?
A squid has ten limbs: eight arms and two longer tentacles.
What is a squid?
A squid is a marine animal with a streamlined body and ten limbs.
Are squids intelligent?
Squids are not as renowned for intelligence as octopuses but are skilled predators.
Can squids emit ink?
Yes, squids can also emit ink.
Do octopuses have shells?
No, octopuses do not have internal shells.
Do squids have shells?
Squids have a thin internal shell called a pen.
How do squids move?
Squids are fast swimmers, thanks to jet propulsion.
What's the plural of octopus?
The plural can be "octopuses" or "octopi."
What's the plural of squid?
The word "squid" is both singular and plural.
Are octopuses intelligent?
Yes, octopuses are known for their problem-solving skills.
Can octopuses emit ink?
Yes, octopuses can emit ink for defense.
What is an octopus?
An octopus is a marine animal with eight arms and a sack-like body.
How do octopuses move?
Octopuses generally crawl or swim slowly.
How many arms does an octopus have?
An octopus has eight arms.
Is squid commonly eaten?
Yes, squid is often consumed as food, particularly in the form of calamari.
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Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
