Octopuses and squid have 8 limbs, look very similar, and are both in the cephalopod family. To the uninitiated, it can be hard to tell them apart, so how do you know if you’re looking at a squid or an octopus?
The difference between squids and octopi: Squid has a triangle-shaped head while octopi have round-shaped heads. Squid have tentacles and arms while octopi only have arms.
There are a few more key indicators to look out for:
Appearance: Round Head and Eight Arms vs Triangle Head and Tentacles
Although an octopus looks like it’s just a head on top of legs, it actually has something known as a “mantle”, which is essentially its body.
The mantle houses the animal’s organs, as well as several key muscles that aid with respiration.
It still has a head, but most of that upper structure is the mantle and it’s usually rounded.
Octopuses have 8 arms and two eyes with rectangular pupils.
As for squid, they also have a mantle, but it’s more triangle in shape and has two fins—one on either side.
Squid have eight arms as well, but there are also two additional tentacles that look like longer arms.
Location: Seabed vs Deep Ocean
Many species of squid live in the deep ocean, including the giant squid and colossal squid, which can be found at depths of over 1,000 feet.
Octopuses can usually be found on the ocean floor and typically reside in crevices.
The exact depth will depend on the species, but some thrive at over 10,000 feet.
Both squid and octopuses thrive in saltwater and can be found in temperate and tropical regions all over the world.
Diet: Tough Beaks vs Long Tentacles
Squid typically feed on shrimp and fish while octopuses scour the ocean floor for crustaceans.
The way that these two species hunt and eat also differs.
An octopus will use its tentacles to catch these bottom-dwelling crustaceans before using its beak to crush shells.
Some species inject paralyzing venom inside the mollusk shell to make the process easier.
Squid catch food with their two long tentacles and then consume it with their sharp beaks.
Reproduction: Complete Devotion vs Individuality
A male octopus is equipped with a specialized arm known as the hectocotylus that allows it to transfer sperm to a female octopus.
Once fertilized, the female will lay eggs and remain completely devoted to them for many days or weeks.
Squid will usually drop their eggs onto the ocean floor and then leave them to survive on their own.
Both male squid and male octopuses die shortly after mating and in some cases, the female is the one who kills them.
Female octopuses will also starve themselves and die by the time the eggs hatch.
It’s an unusual habit, but it’s believed to be an evolutionary trait.
Octopuses are cannibalistic by nature and if there are still adults around when the babies are born, they are more likely to see them as a food source.
By dying before the young hatch, adult octopuses can also remove themselves from the food chain and reduce competition for food.
Summary: Squid vs Octopus
As you can see, there are some differences between a squid and an octopus, although these differences are slight and it gets confusing when you consider the many different species of both squid and octopus.
In addition to the above, squid can live a little longer than octopuses, but both of these animals have very short lifespans and die shortly after mating.