10 of the Oddest Marine Animals

A male weedy sea dragon swimming in shallow water with sunlight shining through from above

David Haintz / Getty Images

Earth's waters are home to a variety of unusual aquatic creatures. Some have unique forms of camouflage, and others have creative ways of hunting prey. From the scaleless mandarinfish that oozes toxic mucus to the vampire squid that draws itself into a cape, sea creatures look and behave in mysterious ways. Here are 10 examples of some of the oddest creatures found in the sea.

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Longfin Batfish

A pair of longfin batfish swimming on a shallow reef

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Next time you see a floating leaf in the Indo-Pacific, look again. Juvenile longfin batfish inhabit seagrass and floating sargassum weed beds and feed on plankton and jellyfish found within. The juvenile have been known to act like leaves floating in the water to mimic their surroundings as protection from predators.

Adult longfin batfish are large, growing up to 24 inches in length. Adult fish are found at depths of up to 65 feet in lagoons and reefs.

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A blue, green, and orange mandarinfish swimming next to gold coral

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The striking, multi-colored mandarinfish is a scaleless fish found in the western Pacific. Because of its lack of scales, it oozes a smelly, toxic mucus coating for protection. But their sticky coating isn’t the only thing that makes mandarinfish unusual. They also have a flat, pushed in head, are tiny in size, at just over 2 inches, and have bold color patterns that match their coral reef surroundings.

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Electric Eel

Three electric eels in a shallow tank with green plants at the bottom

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The novel physiology of the electric eel made it essential to learning about animal electricity. Rows of electroplates lining its body enable the electric eel to immobilize or kill its prey, but it also uses electric charge to defend itself, to communicate, and to navigate. When prey is not visible, these eels can use their charge to cause prey to move involuntarily, creating vibrations in the water so they can be easily located by the eel. Electric eels can grow to as long as 8 feet and weigh over 40 pounds.

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Weedy Sea Dragon

Yellow and orange weedy sea dragon nibbling on a green underwater plant

Shin Okamoto / Getty Images

Native to the shoreline waters off Australia, weedy sea dragons resemble the seaweed in which they live. As these tiny creatures drift along with the current, camouflage protects them from predators. The accent colors on their bodies and their weed-shaped appendages all add to their weed-like appearance. Like other seahorses, they have elongated snouts, but unlike seahorses, they do not have prehensile tails.

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Vampire Squid

display of black vampire squid in Natural History Museum, London

Emőke Dénes / Wikimedia Commons / CC BY -SA 4.0

Neither squid nor octopus, the vampire squid, which dwells in the deep ocean, uses its large, bulging eyes to see its prey. The vampire squid is one of the few creatures able to survive in depths up to 8,000 feet, where oxygen levels are as low as five percent. Aside from huge eyes, the vampire squid can turn itself inside out to use a Dracula-like cape webbing as a shield. The creepy critter also changes colors and glows in the deep sea.

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Manta Ray

A manta ray, with its wings curved upward, above a shallow reef filled with fish

Michele Westmorland / Getty Images

Manta rays don’t just use their massive fins to get around; these appendages are an integral part of their feeding ritual. When feeding while swimming in a straight line, manta rays turn their fins downward, forming a circle in front of them to trap food and funnel it into their mouths. They also perform backflips in the water to stimulate their food of choice, plankton. Mantas can even feed while swimming sideways, with one fin pointing upward toward the water’s surface.

Mantas also cooperate with other manta rays to form chains underwater, with each ray lining up with their fins turned downward to feed.

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A lionfish swimming among pink and red corals

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There's a reason the lionfish doesn't look friendly. This creature is one of the most aggressive and invasive species in the world. The long, mane-like fins of the red lionfish contains 18 venomous spines, and its sting is one of the worst of all fish. Lionfish are not only dangerous to the fish they hunt, but their voracious appetite causes significant damage to the biodiversity of the already fragile reef systems they inhabit.

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Three blobfish on a metal scale

NOAA / Wikimedia Commons / Public Domain

The blobfish, possibly the oddest looking of this bunch, actually has advantages in its habitat. This odd fish has adapted to live in the deep sea off of Australia at depths of up to 4,000 feet. It has a squishy, gelatinous exterior that floats more easily in the depths it inhabits. Since blobfish have no muscles, they simply eat whatever floats their way.

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Frilled Shark

The side profile of a frilled shark with its mouth open near the water's surface

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This rarely encountered shark lives in the deep waters off the Atlantic and Pacific oceans. Deemed a "living fossil," the frilled shark looks ancient and is often mistaken for an eel, particularly due to its eel-like style of swimming. Its strange body shape is thought to help it strike like a snake to catch prey, and its huge mouth along with thin, sharp teeth allow the shark to trap its food inside its mouth with ease. Inhabiting depths of up to 4,900 feet, frilled sharks are rarely encountered in the wild.

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A black spotted archerfish swimming near gray rocks underwater

PeachLoveU / Getty Images

While they may look like they are splashing around having fun, archerfish are actually skilled hunters. They form a tube with their tongue and shoot water through the surface to knock insects into the water, where they catch and eat them. And they can hit their target from as far as 4 feet away. Archerfish will also jump out of the water to capture insects in midair.