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15 Facts About the Lion’s Mane Jellyfish

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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.

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Big Questions
Why Do Cats Freak Out After Pooping?
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Cats often exhibit some very peculiar behavior, from getting into deadly combat situations with their own tail to pouncing on unsuspecting humans. Among their most curious habits: running from their litter box like a greyhound after moving their bowels. Are they running from their own fecal matter? Has waste elimination prompted a sense of euphoria?

Experts—if anyone is said to qualify as an expert in post-poop moods—aren’t exactly sure, but they’ve presented a number of entertaining theories. From a biological standpoint, some animal behaviorists suspect that a cat bolting after a deposit might stem from fears that a predator could track them based on the smell of their waste. But researchers are quick to note that they haven’t observed cats run from their BMs in the wild.

Biology also has a little bit to do with another theory, which postulates that cats used to getting their rear ends licked by their mother after defecating as kittens are showing off their independence by sprinting away, their butts having taken on self-cleaning properties in adulthood.

Not convinced? You might find another idea more plausible: Both humans and cats have a vagus nerve running from their brain stem. In both species, the nerve can be stimulated by defecation, leading to a pleasurable sensation and what some have labeled “poo-phoria,” or post-poop elation. In running, the cat may simply be working off excess energy brought on by stimulation of the nerve.

Less interesting is the notion that notoriously hygienic cats may simply want to shake off excess litter or fecal matter by running a 100-meter dash, or that a digestive problem has led to some discomfort they’re attempting to flee from. The fact is, so little research has been done in the field of pooping cat mania that there’s no universally accepted answer. Like so much of what makes cats tick, a definitive motivation will have to remain a mystery.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at

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Listen to the Impossibly Adorable Sounds of a Baby Sloth
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Sometimes baby sloths seem almost too adorable to be real. But the little muppet-faced treasures don't just look cute—turns out they sound cute, too. We know what you're thinking: How could you have gone your whole life without knowing what these precious creatures sound like? Well, fear not: Just in time for International Sloth Day (today), we have some footage of how the tiny mammals express themselves—and it's a lot of squeaking. (Or maybe that's you squealing?)

The sloths featured in the heart-obliterating video below come from the Sloth Sanctuary of Costa Rica. The institution rescues orphaned sloths, rehabilitates them, and gets them ready to be released back into the wild.

[h/t The Kid Should See This]


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