11 Amazing Octopus Species

Octopuses are eight-limbed, soft-bodied wonders of the underworld. With their big, rounded heads, bulging eyes, and tentacles, the sea creatures are known for their unique appearance, but their physical features can differ from species to species.

Octopuses share a class (Cephalopoda) with squids and cuttlefish. They belong to the order Octopoda, of which there are two suborders, Cirrina and Incirrina—the former has an internal shell and two fins on its head, whereas the latter doesn't. There are around 300 known species of octopus, most of them incirrates.

These eleven underscore the majestic octopus's variety of beauty and strangeness.

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Common Octopus

The common octopus (Octopus vulgaris) is the quintessential eight-limbed mollusk. It's the most studied of all octopus species, probably in part because it's one of the most widely distributed. The common octopus can be found in the shallows of tropical, subtropical, and temperate waters from the eastern Atlantic to the southern coast of South Africa.

Though described as "common," this animal is extraordinarily smart. It's reportedly the most intelligent of all invertebrates, able to solve mazes and get itself out of complex containers.

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Coconut Octopus

The coconut octopus (Amphioctopus marginatus) is named for a peculiar behavior: It gathers coconut shells that fall on the tree-lined beaches of the Pacific coast and uses them for shelter. It will even carry its treasures from place to place, holding them with its six "arms" while walking on the ocean floor with its two "legs." Some researchers claim that by using shells for shelter and defense, this octopus species is engaging in tool use, although the notion is disputed.

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Giant Pacific Octopus

The giant Pacific octopus (Enteroctopus dofleini) is the largest species in the world, weighing as much as 150 pounds and measuring up to 15 feet long. It's also known for its ability to change color, a skill shared by many cephalopods, though the giant Pacific octopus does it with particular flair. It can blend in with its surroundings or use its shade-shifting powers to ward off threats.

Found anywhere from tide pools to 6,600 feet below the ocean surface, the species hunts a range of crustaceans, fish, and other octopuses.

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Dumbo Octopus

The dumbo octopus (Grimpoteuthis) is actually a name for a group of deep-sea umbrella octopuses, all of which have fins resembling the ears of Dumbo the elephant. These fins also put it in the smaller Cirrina suborder, although scientists say the octopus exhibits a coiled body posture unlike any other cirrate.

Dumbo octopuses are the deepest-dwelling of all octopus species, found as far as 13,000 feet under water. While most are quite small, some can reach six feet. Unlike other octopus species, dumbo octopuses don't have ink sacks, presumably because they don't encounter as many predators at such great depths.

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Blue-Ringed Octopus

One of the most stunning octopus species is the blue-ringed octopus (Hapalochlaena), known for its namesake azure spots. But though beautiful, those blue rings signify danger.

All octopuses are venomous, the Ocean Conservancy says, but this one's venom is 1,000 times more powerful than cyanide—and it packs enough to kill 26 humans. For this reason, the four species of blue-ringed octopus are some of the most dangerous animals in the ocean.

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Atlantic Pygmy Octopus

A full-grown Atlantic pygmy octopus (Octopus joubini) is only about six inches in length. However, despite their tiny size, the species is incredibly smart. It uses shells and other objects as hiding places and uses sand to camouflage itself.

It's also a vicious predator, known to use its sharp radula to drill a hole into crustacean shells, then spit poisonous saliva inside to paralyze its victim.

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Mimic Octopus

The mimic octopus (Thaumoctopus mimicus) is one of the most mind-boggling octopus species thanks to its unique ability to impersonate other sea creatures. By changing its color and contorting its body, the octopus can transform into as many as 15 other animals (lionfish, jellyfish, sea snakes, shrimp, crabs, etc.). It does this to evade potential predators but will also mimic animals in its own predatory efforts.

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Caribbean Reef Octopus

Several species of octopus are skilled chameleons, but the Caribbean reef octopus (Octopus briareus) is one of the masters. It can rapidly change its colors, patterns, and even its skin texture to blend in with its surroundings as it moves around coral reefs. The ability comes in handy when hiding from large bony fish, sharks, and other predators.

Strictly nocturnal, the Caribbean reef octopus hunts for fish and crustaceans under the cover of darkness.

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Seven-Arm Octopus

Despite its name, the seven-arm octopus (Haliphron atlanticus) has eight arms. The misnomer comes from the fact that males have a modified arm they use for egg fertilization that is held in a sac beneath their eyes.

This species is similar in size to the Pacific giant octopus, but what sets it apart is its elusiveness. The deep-sea dweller has been spotted only a few times by researchers using submersibles. During one of those times, it was eating a jellyfish—an unlikely meal for an octopus that may provide insight into how the species survives at such depths.

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California Two-Spot Octopus

This colorful octopus has two bright blue spots beside its eyes, thought to be a defense mechanism against predators. It resides in fairly shallow waters, as it likes to hunt and crawl in search of prey, as well as hide among rocks on the sandy sea bottom. If startled, it may quickly jet out into the open water. It's timid but friendly, and poses no threat to humans. Sometimes it will change its coloring to camouflage, which means its appearance can vary from mottled brown to gray with yellow spots. This octopus grows to around 3 feet in length.

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Blanket Octopus

A highly unusual creature, the blanket octopus spends its entire life in the open ocean, where it looks like a wet blanket floating in the water, thanks to a membrane connecting its arms. Perhaps the most curious fact is the size discrepancy between males and females. Females grow up to 6.5 feet, while males stay only one inch in size. They mate when the male secretes his sperm in a detachable arm, which he then inserts into the female before dying.

How Smart Are Octopuses?

Octopuses might lack bones, but they certainly do not lack brains. They are the world's smartest invertebrates. How do we know? Here's the evidence:

Octopuses use tools, such as the coconut shells for shelter and jellyfish tentacles for defense.
Experts believe they can recognize individuals outside of their own species, including humans.
They work with other species, like groupers, to hunt.
They excel at puzzles such as unscrewing lids to jars and fitting L-shaped objects through small square openings.
Octopuses can retain information for several months.
They're emotional creatures, capable of feeling affection and excitement.