8 Amazing Octopus Species

Blue-ringed octopus walking on the sea floor
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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 around 300 known species.

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

Coconut Octopus

Coconut octopus hiding in a coconut shell

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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.

Giant Pacific Octopus

Giant Pacific octopus stretching its behemoth arm

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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.

Dumbo Octopus

Dumbo octopus floating in dark water

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The dumbo octopus (Grimpoteuthis) is actually a name for a group of deep-sea umbrella octopuses, all of which have the characteristic fins resembling the ears of Dumbo the elephant. They have been found as far as 13,000 feet under water, which makes them the deepest-dwelling of all octopus species. While most are quite small, large dumbo octopuses can reach 6 feet, the Aquarium of the Pacific says. Unlike other octopus species, dumbo octopuses don't have ink sacks, presumably because they don't encounter as many predators at such great depths.

Blue-Ringed Octopus

Blue-ringed octopus with light-reflecting spots

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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.

Atlantic Pygmy Octopus

Atlantic pygmy octopus swimming on the bottom of the sea

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A full-grown Atlantic pygmy octopus (Octopus joubini) is only about 6 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.

Mimic Octopus

Mimic octopus adjusting its tentacles to resemble another sea animal

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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.

Caribbean Reef Octopus

Caribbean reef octopus blending in with a colorful reef

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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.

Seven-Arm Octopus

Seven-arm octopus at the surface of the water
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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 its eye. 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 of 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.