10 Extraordinary Jellyfish Species

Cauliflower Jellyfish

The cauliflower jelly (Cephea cephea) is named so because of the wartlike projections on its bell. Found in the mid-Pacific, the Indo-Pacific, and the Atlantic Ocean off of West Africa, the crowned jelly—as it's sometimes also called—is an oceanic species that can grow relatively large, reaching diameters of up to two feet.

Mangrove Box Jelly

The mangrove box jelly (Tripedalia cystophora) is one of the smallest jellies in the sea—growing to be only the size of a grape. But what's even more unique is its cube-shaped medusa, a notable deviation from the familiar dome silhouette of most jellies. Its distinct squareness allows this cool jellyfish to move rapidly through the water.

Crystal Jellyfish

In the waters off North America’s West Coast lives the crystal jellyfish (Aequorea victoria), a type of jellyfish that is completely colorless and has long, wispy tentacles lining its glasslike bell. The remarkably gorgeous creature looks crystal clear in the daylight—hence its name—but its transparency belies a brighter side: Crystal jellyfish are actually bioluminescent, glowing green-blue when disturbed.

White-Spotted Jellyfish

White-spotted jellies (Phyllorhiza punctata)—known for their speckled crowns—live in the western Pacific, from Australia to Japan. They are filter feeders that can sift through more than 13,000 gallons of water a day each in their quest for minuscule zooplankton.

The downside of their presence is that a swarm of them can clear an area of zooplankton, leaving none for the fish and crustaceans that also rely on them. In the Gulf of California, the Gulf of Mexico, and the Caribbean Sea, they're considered an invasive species.

Upside-Down Jellyfish

The upside-down jellyfish (Cassiopea) rests its bell on the surface of the seafloor and swims with its stubby oral arms facing the sky. It does this to expose the symbiotic dinoflagellates living in its tissues to the sun, allowing them to photosynthesize, the Monterey Bay Aquarium says. The upside-down jelly is found in warm water, such as that around Florida and the Caribbean.

Black Sea Nettle

Despite its name, the black sea nettle (Chrysaora achlyos) is actually red in color, like many other deep-sea dwellers. The rich color allows them to blend in with the dark water. It's found deep in the Pacific off Southern California and is a giant among jellyfish. Its bell can reach three feet in diameter, its arms 20 feet long, and its stinging tentacles 25 feet long. Because they're not often found in the wild and difficult to raise in captivity, black sea nettles are still relatively obscure.

Fried Egg Jellyfish

It's obvious where the fried egg jellyfish (Cotylorhiza tuberculata) got its name. Its yellow bell is surrounded by a lighter ring, often resembling an egg yolk. The mouth-arms of the fried egg jellyfish (also called the Mediterranean jellyfish) are truncated, and there are longer projections with disklike ends, giving it the look of a dome dotted with purple and white pebbles. This species survives for only about six months, from summer to winter, dying when the water cools down.

Lion's Mane Jellyfish

The lion's mane jellyfish (Cyanea capillata) is the largest known jellyfish species, able to grow up to six and a half feet long. The average length is a foot and a half. Its "mane" is made up of hundreds (sometimes more than a thousand) of tentacles divided into eight clusters. Sometimes called the Arctic red jellyfish or the hairy jelly, it lives in the boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans.

Atolla Jellyfish

The Atolla jellyfish (Coronate medusa) is widely distributed around the world. Like many other deep-sea dwellers, this super cool jellyfish has bioluminescent abilities, but it doesn't use its bioluminescence to attract prey like the rest. Instead, it glows to deter predators.

When an Atolla jellyfish is attacked, it creates a series of flashes that attract even more predators, with hopes of them being more interested in the original attacker than the jellyfish itself. This is why this type of jellyfish has also been called the alarm jellyfish.

Narcomedusae

The Narcomedusae—its scientific name is sometimes shortened to "narcos"—is a rather unusual-looking species of jellyfish that can have a whopping dozen or more stomach pouches. To keep them full, it will swim while holding its long, poison-filled tentacles out in front of it. Scientists believe this helps them ambush prey more effectively.