15 Facts About the Lion’s Mane Jellyfish

The stunning—and stinging—lion’s mane jellyfish (Cyanea capillata) ranks among earth’s most beautiful creatures. Let's tip our scuba masks to this amazing invertebrate.

1. It Can Grow Up to 120 Feet Long.

By comparison, the largest recorded blue whale was a paltry 108 feet long. But don’t go around calling this jellyfish the world’s longest animal. Some marine biologists claim the saltwater bootlace worm (Lineus longissimus) deserves that title—when fully extended, it can stretch 180 feet from end to end!

2. It Eats and Expels Waste Through the Same Orifice.

Jellyfish have a very special opening designed to perform double-duty as both a mouth and an anus. At least they’re economical.

3. It Isn’t Immune to Predation.

As you can see in this clip (filmed by National Geographic), lion’s mane jellyfish need to watch their backs around famished anemones. Also, leatherback sea turtles have been seen gobbling them up off the coasts of Canada. The reptiles' throats contain backward-pointing spikes called oral papillae to help move food in the direction of the stomach; they also make escaping pretty difficult.

4. Lion’s Mane Jellyfish Come in a Variety of Colors.

Large individuals are often red or purple, while smaller specimens tend to be shades of tannish-orange.

5. A Single Specimen May Have Stung Over 50 People.

June 16, 2010 was a weird day for New England beach-goers. Somewhere between 50 and 100 swimmers were stung off the coasts of Rye, New Hampshire and, when a 40-pound lion’s mane corpse was found at the scene, the authorities felt they’d found their perpetrator. But could a solitary jellyfish really inflict so much mayhem?

“It’s certainly not common,” marine biologist Sean Colin told LiveScience, “but it’s certainly within the realm of possibility because they do have so many tentacles if they’re that large.” Colin hypothesizes that, since dead jellies can still sting, maybe the body was broken up into several large chunks which spread out and contacted unsuspecting visitors. We’ll probably never know for sure.

6. These Guys Can Have up to 1200 Tentacles.

These are arranged in eight sets that contain between 70 and 150 individual tentacles apiece. Now there’s some Grade-A nightmare fuel…

7. Unfortunately, a Famous Picture was Faked.

As far as being awesome is concerned, nature doesn’t need the Internet’s help. Perhaps you’ve seen this photo, which happens to be Google Images’ number one search result for “giant jellyfish.” Many blogs and news sites have claimed that this thing is an especially-large lion’s mane jellyfish. But so far as we know, this species has a maximum diameter of only seven and a half feet—far smaller than the monster pictured here. What gives? As you might have guessed, it's Photoshopped.

8. It Makes Do With a Year-Long Lifespan.

Believe it or not, one type of jellyfish may be functionally immortal. Sadly, the lion’s mane jelly doesn’t follow suit.

9. The Lion’s Mane Jellyfish Like it Cold.

Geir Friestad, Flickr

Frequent denizens of harsh, Arctic waters, lion’s mane jellyfish are seldom seen below the northern 42nd parallel. Also, they gravitate towards the surface and almost never venture beneath depths of 66 feet.

10. Like Other Jellyfish, It Reproduces Both Sexually and Asexually.

Jellies take on several forms in their complicated life cycles. Upon entering what’s called the “medusa” stage and becoming “adults,” they can reproduce by releasing sperm and eggs. However, as stationary entities rooted to the ocean floor while in the “polyp” stage, they’re capable of asexually cloning themselves.

11. Also Like Other Jellyfish, It (Technically) Lacks a Brain.

Derek Keats, Flickr

In all fairness, contrary to popular belief, these animals do have central nervous systems—a ring of nerves can be found nestled in their “hoods” (or “bells”). So there.

12. Some Scientists Think That Their Population is Booming

Though the jury’s still out, many have argued that—due to factors like over-fishing and rising global sea temperatures—jellyfish numbers may be skyrocketing. Who knows? If true, this might mean we’ll all start munching on more dried jellies at seafood restaurants.

13. Lion’s Mane Jellies Tend to Group Up.

A.Davey, Flickr

C. capillata sometimes swim together in huge, kilometer-wide clusters called “shoals.”

14. Schools of Fishes Often Surround Them

While deadly to smaller animals (including other jellyfish), lion’s mane jellyfish stings don’t have much of an effect on fish of the Caranx genus, which actively seek the invertebrates out and hover near their tentacles for protection.

15. Sherlock Holmes Once Had to Contend with a Lion’s Mane Jellyfish.

The world’s greatest detective had never faced a squishier adversary. In The Adventure of the Lion’s Mane (1926), he deduces that an unlucky professor had been stung to death by one of these spineless predators—which he proceeds to track down and flatten with a boulder. No word on whether or not we’ll be seeing Benedict Cumberbatch go toe-to-tentacle with one.

Watch How a Bioluminescence Expert Catches a Giant Squid

Giant squid have been the object of fascination for millennia; they may have even provided the origin for the legendary Nordic sea monsters known as the Kraken. But no one had captured them in their natural environment on video until 2012, when marine biologist and bioluminescence expert Edith Widder snagged the first-ever images off Japan's Ogasawara Islands [PDF]. Widder figured out that previous dives—which tended to bring down a ton of gear and bright lights—were scaring all the creatures away. (Slate compares it to "the equivalent of coming into a darkened theater and shining a spotlight at the audience.")

In this clip from BBC Earth Unplugged, Widder explains how the innovative camera-and-lure combo she devised, known as the Eye-in-the-Sea, finally accomplished the job by using red lights (which most deep-sea creatures can't see) and an electronic jellyfish (called the e-jelly) with a flashy light show just right to lure in predators like Architeuthis dux. "I've tried a bunch of different things over the years to try to be able to talk to the animals," Widder says in the video, "and with the e-jelly, I feel like I'm finally making some progress."

[h/t The Kid Should See This]

Big Questions
Why Are There No Snakes in Ireland?

Legend tells of St. Patrick using the power of his faith to drive all of Ireland’s snakes into the sea. It’s an impressive image, but there’s no way it could have happened.

There never were any snakes in Ireland, partly for the same reason that there are no snakes in Hawaii, Iceland, New Zealand, Greenland, or Antarctica: the Emerald Isle is, well, an island.

Eightofnine via Wikimedia Commons // Public Domain

Once upon a time, Ireland was connected to a larger landmass. But that time was an ice age that kept the land far too chilly for cold-blooded reptiles. As the ice age ended around 10,000 years ago, glaciers melted, pouring even more cold water into the now-impassable expanse between Ireland and its neighbors.

Other animals, like wild boars, lynx, and brown bears, managed to make it across—as did a single reptile: the common lizard. Snakes, however, missed their chance.

The country’s serpent-free reputation has, somewhat perversely, turned snake ownership into a status symbol. There have been numerous reports of large pet snakes escaping or being released. As of yet, no species has managed to take hold in the wild—a small miracle in itself.

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