And the Award Goes To…

No jellyfish took home any accolades from the Academy of Motion Pictures last week (though a movie feature of Spineless would no doubt rock the box offices.) Nonetheless, recently a couple species of jellies have been officially bestowed some sweet superlatives.

Last month, Craig McLean, a scientist at the National Evolutionary Synthesis Center in Durham, North Carolina ended the debate, once and for all,  over the biggest ‘fish’ in the sea. (Actually, there’s still some question, keep reading.) McClean had noticed that reports of sea creatures often suffer from the same sort of exaggerations fishermen make about the one that got away. As an example, giant squid are widely reported to reach 60 feet, while documented measurements come in closer to 40 feet. To me, this sounds like a conversation that got spun up over a few beers. But regardless of how it started, McClean and his colleagues set out to determine just how bad the fish tales were. Using scientific literature, museum collections, and interviews with experts in various fields, they assembled a database of the sea’s behemoths and ranked them by size.

Lion's mane jelly
Lion’s mane jelly from the Oregon aquarium, notice the tangle of tentacles.

And which animal came home with the prize? It wasn’t no stinking whale, that’s for sure. The award for the sea’s longest animal went to…the lion’s mane jellyfish (Cyanea capillata). Roaming through the northern seas of the both the Atlantic and Pacific, this jelly’s eight-foot-wide ochre bell hovers above a dense mat of thin hairlike tentacles that riffle the water like a lion’s mane, and some of them stretch over 120 feet. For comparison, the blue whale is yards shorter, measuring a mere 108 feet.

The prize-winning individual was documented in 1865 by a most prominent naturalist, Alexander Agassiz, whose father, Louis, founded the Museum of Comparative Zoology at Harvard. Young Alex wrote, “I measured myself a specimen at Natant, the disk of which had attained a diameter of seven and a half feet, the tentacles extending to a length of more than one hundred and twenty feet.”

Although they award the prize to this lion’s mane, McClain and his coauthors do have a few small qualms with the 150-year-old record, even if it was written by an Agassiz. No similarly long lion’s mane has been seen since, and no details are given about how the measurement was made. What’s more, in captivity, lion’s mane tentacles  have a tendency to break off like dry hair and become entangled in other tentacles, extending the apparent length of the animal.

Praya dubia
Praya photographed by Monterey Bay Research Institute Bioluminescence and Biodiversity Expedition

Whether those 120-foot tentacles are extensions or the real thing, may not really matter though. According to the Monetary Bay Aquarium, there’s another jellyfish that’s even longer than the lion’s mane that McClain and his drinking buddies (okay, I don’t know that) somehow missed in their grand survey. The giant siphonophore, Praya dubia lives a thousand feet below the surface of the ocean. It’s several swimming bells pull yards and yards of stinging bells behind it, forming a curtain over 130 feet long. To be fair, McClean and their coauthors don’t explain how they determined what qualified as a megafauna, and it’s possible they disqualified the siphonophore for being a colony of individuals rather than a single being.

Me and a fairly small Nomura's jellyfish
Me and a fairly small Nomura’s jellyfish

When it comes to the heaviest jelly, the Nomura’s jelly (Nemopilema nomurai) easily won McClean’s prize, tipping the scales at 440 pounds, about the size of my refrigerator. To grow that big in the one year they live as a medusa, these jelly-zillas add 2-10% to their body mass each day. I famously (well, it will be famous one day when Spineless is in theaters) chased a Nomura’s off the coast of tiny Tsushima Island in 2012 with the help of a wonderful Japanese fisherman named Sukamoto-san. The jelly we caught that day was–and see how I’m telling the truth here–probably about 150 pounds, a puny specimen.


Below is the fabulous infographic that came out of McClean’s study. It’ll save you a lot of work the next time you’re drinking beers and your buddies just have to know, what’s the biggest creature in the sea?

Chart of relative sizes of sea creatures.


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