Most people know that octopuses have eight legs or arms. But did you know that these alien-looking creatures have nine brains? It’s little wonder these animals are so intelligent!

Octopuses have inspired movies, featured in popular songs, and appeared in legends, and in 2010, an octopus named Paul was asked to predict the result of World Cup football matches! Despite its notoriety, octopus appears in various forms as a popular dish on restaurant menus around the world.

Octopuses have been around since the Jurassic period over 200 million years ago. Today, there are around 300 species of octopuses living in every ocean on the planet, some inhabiting shallow tidal pools and others hanging out at the bottom of the deep ocean.

Read this guide to learn more about the remarkable octopus!Etymology 

Octopus is undoubtedly a strange word, but where did it come from? It’s thought that octopus is a Latin version of the Greek word októpus, which translated means “eight-foot.”

There’s much debate around the correct plural of octopus. So, let’s bust a few common myths!Octopi is the oldest plural for octopus, originating from the belief that the word comes from Latin origins. However, that’s incorrect. Since octopus is actually derived from Greek, the plural should be Octopodes.

But although that’s technically correct, the word octopodes is almost never used.

The correct plural of octopus is octopuses since that ending matches the English adoption of the word, which is commonly used today.

So, now you know!

Taxonomy

The Octopus is a mollusk that belongs to the order Octopoda. Within that order are around 289 species that sit within the class Cephalopoda, along with cuttlefish, nautiloids, and squids.

Octopuses belong to the Kingdom Animalia, just like you and I!Evolution

Octopuses evolved back in the Cambrian period, some 530 million years ago, from a primitive mollusk. Coleoidea diverged from the nautiloids around 416 million years ago during the Devonian period.

Octopuses and squids further evolved by bringing their shells inside their bodies. Then, 276 million years ago, the two species split again into the Vampyropoda and Decabrachia groups.Octopuses came from primitive creatures within the Vampyropoda in the Jurassic period and lived on the ocean floor in shallow environments.

Unfortunately, since octopuses comprise mainly soft tissue, fossils are rare.Physical Appearance

Octopuses belong to the class Cephalopoda, meaning “head foot” in Greek. In this class of creatures, the feet and head merge to form one animal.

Octopus Anatomy

The octopus has a ring of eight arms of equal length surrounding a head, which contains the animal’s mouth and brain. The underside of the creature’s arms is covered with suckers sensitive to taste and touch.

The octopus uses its two rear arms to walk on the sea floor, while the other six are used for foraging for food—the animal’s arms trail behind it when the octopus is swimming.

The creature’s sack-like body sits on top of the head and has two sensitive, complex eyes, while the octopus’s mouth is underneath. Octopuses have a hard beak that the animal uses to break into the shells of crustaceans.

Octopus Size

Octopuses range in size tremendously.

For example, the Giant Pacific Octopus, Enteroctopus dofleini, found off the US Pacific coast from California to Alaska, is the largest octopus in the world, having an arm span of up to 14 feet and weighing up to 33 pounds!

There are many fishermen’s tales surrounding the Giant Pacific Octopus, leading to some popular myths and legends about the creature’s size. For example, one recorded specimen had an arm span of 30 feet and weighed an impressive 600 pounds!

In contrast, the smallest octopus in the world is the Wolfi Octopus, having only a 1-inch arm span and weighing just 1 gram!

External Characteristics

Octopuses are solitary animals that are experts in concealment and camouflage. Since the octopus has no skeleton, its body is made of around 90 percent muscle, allowing the creature to squeeze into tiny spaces where it can hide.

In addition, the octopus’ skin contains chromatophores, cells that enable the animal to change color and pattern to match its surroundings perfectly.