There Are 300 Types of Octopus Species, Some With Internal Shells

An octopus blends in with the kelp on the reefs in the Channel Islands National Park. Douglas Klug / Getty Images

Octopuses are known their eight legs, squishy bodies and impressive problem-solving skills. But did you know there are over 300 types of octopus species?

Some can change color in an instant. Others glow in the dark. Some mimic sea snakes. A few even drift through coral reefs like underwater phantoms.

Let's take a closer look at how scientists classify these intelligent underwater creatures.

Octopus Classification

Octopuses belong to the order Octopoda, a group of mollusks known for their soft bodies and advanced nervous systems.

This order is divided into two suborders: Cirrina (or Cirrata), which includes deep-sea octopuses with small internal shells and cirri (tiny, hair-like structures near their suckers); and Incirrina (or Incirrata), which includes the more familiar, shell-less octopuses found in coral reefs and shallow waters.

Within these suborders, octopuses are further divided into families, which group species based on their physical characteristics, behaviors and habitats.

Each family contains multiple octopus species, ranging from the massive giant Pacific octopus to the tiny Octopus wolfi. Scientists continue to discover new species.

2 Octopus Suborders

1. Cirrina (Cirrate Octopuses)

Cirrate octopuses, or deep-sea octopuses, have small internal shells and webbed arms, often possessing bioluminescent suckers to navigate the dark ocean depths. Here are some specific species that fall within the Cirrate suborder.

Opisthoteuthidae: Known as umbrella octopuses, these species have webbed arms that create an umbrella-like shape when extended.
Cirroteuthidae: These species are deep-sea octopuses with elongated bodies and large fins that help them glide through the water.
Stauroteuthidae: These species are unique for their bioluminescent suckers, which may help attract prey in the deep ocean.
Grimpoteuthididae: These species is home to the famous dumbo octopus, which uses its ear-like fins to propel itself through the depths.
Cirroctopodidae: These species are deep-sea dwellers that remain largely mysterious due to their extreme habitat.

2. Incirrina (Incirrate Octopuses)

Incirrina octopuses — the more familiar shell-less species — are found in shallow waters and coral reefs, showcasing remarkable intelligence, camouflage abilities and problem-solving skills. Here are some specific species that fall within the Incirrina suborder.

Octopodidae: These species are the largest family, including familiar species like the common octopus and giant pacific octopus.
Amphitretidae: These species are open-ocean octopuses that drift with the currents and have transparent bodies.
Bolitaenidae: These species are small, gelatinous octopuses often found in mid-water zones, some of which glow in the dark.
Argonautidae: These species contains the paper nautilus, which isn't a true nautilus but creates a delicate, shell-like egg case.
Alloposidae: These species includes the seven-arm octopus, which appears to have only seven limbs because one arm is tucked inside.
Tremoctopodidae: This species is also known as the blanket octopus, known for its dramatic, flowing webbing.
Ocythoidae: These species are the only octopus family with a swim bladder, helping them stay neutrally buoyant in the water column.

12 Most Common Octopus Species

1. Giant Pacific Octopus (Enteroctopus dofleini)

The giant Pacific octopus holds the title of the largest octopus species, with the largest recorded one weighing 600 pounds (272 kilograms). These deep-sea giants are known for their intelligence and long lifespans compared to other octopuses.

2. Common Octopus (Octopus vulgaris)

The ultimate escape artist, the common octopus is a master of camouflage. This species, found in oceans all over the world, is famous for solving puzzles, opening jars and even sneaking out of aquariums.

3. Mimic Octopus (Thaumoctopus mimicus)

A true ocean shapeshifter, the mimic octopus can impersonate sea snakes, lionfish and even flounders. Found in the Indo-Pacific, this clever cephalopod uses its disguise skills to avoid predators.

4. Blue-Ringed Octopus (Hapalochlaena spp.)

Small but deadly, the blue-ringed octopus carries venom powerful enough to paralyze a human within minutes. Found in tide pools and shallow waters, its bright blue rings serve as a warning to potential predators.

5. Caribbean Reef Octopus (Octopus briareus)

A master of camouflage, this species can blend into their environments instantaneously when threatened by predators or sneaking up on its prey. It is known for its striking blue-green coloration and nocturnal hunting habits.

6. Star Sucker Pygmy Octopus (Octopus wolfi)

Meet the tiniest octopus in the world. The star sucker pygmy octopus measures just over an inch (2.5 centimeters) in length and is found in shallow waters. Despite its size, it is just as intelligent and capable as its larger relatives.

7. Dumbo Octopus (Grimpoteuthis spp.)

The dumbo octopus glides through the ocean with its large, ear-like fins. It lives in extreme depths, where it feeds on small crustaceans and worms.

8. Blanket Octopus (Tremoctopus spp.)

This species has long, flowing membranes that look like a billowing cape. Female blanket octopuses are much larger than males, the largest recorded individuals reaching lengths of up to 6 feet (1.8 meters).

9. Coconut Octopus (Amphioctopus marginatus)

The coconut octopus gets its name from its habit of carrying coconut shells for shelter. It is one of the few animals known to use objects for protection.

10. Atlantic Pygmy Octopus (Octopus joubini)

A tiny but mighty predator, this small species inhabits the Atlantic Ocean and is known for its ability to squeeze into the tiniest crevices to hunt for food.

11. California Two-Spot Octopus (Octopus bimaculoides)

Easily recognized by the two blue spots near its eyes, this species is commonly found along the coast of California. It is a favorite among researchers studying octopus intelligence.

12. East Pacific Red Octopus (Octopus rubescens)

Another small but fierce predator, the East Pacific red octopus is also known for its ability to rapidly change colors to blend into its surroundings. It is often found in tide pools and along rocky coasts.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.