Last week, scientists aboard a NOAA Ocean Exploration and Research ship in the Gulf of Mexico captured video of an elusive giant squid—the first recorded sighting in U.S. waters. In the 28-second clip, the cephalopod emerges from the blackness of the deep sea and attacks an electronic jellyfish. After wrapping its tentacles around the luminescent bait, the squid loses interest and disappears in the murk. Since ancient times, philosophers and naturalists have puzzled over this rarely seen enigma. There’s plenty we still don’t know about giant squid, but we’ve learned a lot over the past 20 years.
1. Giant squid eyes are the size of Frisbees.
A staggering 10.5 inches across, a squid’s eyeballs lack the jelly-like substance that gives ours their shape. Instead, they’re filled with water, which leaks out once the invertebrate dies. "The eyes collapse. It's like a collapsed plastic bag,” biologist Dan-Eric Nilsson told NPR in 2012.
2. Female giant squid are bigger than males.
On average, female giant squid are around twice the size of males from the tip of their beaks to the ends of their two longest tentacles.
3. Giant squid suckers can leave ugly battle scars.
The giant squid's main enemy is the sperm whale. While under attack, the squid often retaliate by inflicting large, circular wounds, courtesy of the serrated rings around each sucker.
4.The giant squid’s maximum length is about 43 feet.
At least, that’s what the available evidence tells us. Reports of 60- and 70-footers have never been verified scientifically.
5. Instead of a proper tongue, they use a radula.
This organ rests inside their beaks and is covered with seven rows of denticles—sharp, toothy, backwards-pointing protrusions.
6. There may be just one known species.
A genetic analysis in 2013 suggested that Architeuthis duxis the only species of giant squid, as revealed by a comparison of 43 specimens from around the world. The giant squid gene pool seemed abnormally shallow—all 43 subjects were pretty much indistinguishable in this regard. “It’s completely bizarre,” geneticist Thomas Gilbert said. “How can something be global but have so little variation?” Other researchers, however, argue that there may be as many as eight Architeuthis species out there.
7. Giant squid tentacles can regenerate.
One giant squid corpse found in Canada in 1968 had a partially regenerated tentacle. According to a study of the specimen in the Canadian Journal of Zoology, "the regenerated club differed in length and width, and in the size and pattern of suckers, when compared with the normal tentacular arm." Many cephalopods besides squid are capable of this feat, including octopuses.
8. An estimated 4.3 to 131 million get eaten by sperm whales each year.
The squid regularly show up inside sperm whale stomachs. Approximately 360,000 of these mammals swim the oceans. So, if every sperm whale on Earth devoured an average of one giant squid per month, that means 4.3 million would be offed annually.
But some experts think this figure is way too low. Every single day, male whales put away 300 to 400 squid of various species, while females consume an outrageous 700 to 800 squid. Should Architeuthis represent even 1 percent of their diet, then the whales eat 3.6 million daily. That’s 131 million giant squid killed annually.
9. Giant squid may have helped give rise to sea serpent legends.
In one of Moby-Dick’s more memorable chapters, an Architeuthis slithers towards Captain Ahab’s whaleboat. Apparently, Herman Melville wasn’t a fan—Ishmael describes the squid as a “vast, pulpy mass” complete with “innumerable long arms radiating from its center, curling and twisting like a nest of anacondas.” But Melville wasn't alone. Many believe that this predator’s writhing, snake-like limbs have long inspired sea serpent yarns.
10. 20,000 Leagues Under the Sea grossly overestimates the giant squid’s usual weight.
Jules Verne’s 1869 masterpiece remains impressive today: his novel predicted the invention of both scuba tanks and taser guns. But there are still a few gaffes to be found, particularly during the book’s most iconic scene. When hordes of giant squid attack, the narrator, a French professor named Pierre Arronax, estimates that each one must weigh “between four and five thousand pounds.” But as far as modern scientists can tell, the heaviest animals weigh around a ton—although most are less than 1000 pounds.
11. Like all squids, giant squids have three hearts.
A median heart pumps oxygenated blood throughout the body, which it receives from two smaller ones that pump blood through the gills.
12. Architeuthis penises are about a yard long.
Nobody has ever documented a pair of giant squid getting busy. But biologists suspect that males use their sex organs like syringes, injecting sperm into a female’s skin, where she stores the cells until her eggs need fertilizing. When that happens, the mom-to-be pulls them out of storage (though we’re not sure how).
13. The first giant squid photo ever shot was taken inside of a bathroom.
In 1873, Newfoundland minister Moses Harvey acquired a dead Architeuthis which he laid out over his shower curtain rod and preserved for posterity. He’d purchased this specimen for just $10 from a few local fishermen who’d ensnared it with their nets while out in Logy Bay.
14. Giant squid might be cannibals.
Bits and pieces of one Architeuthis showed up in a live giant squid's stomach. But this doesn’t necessarily prove that giant squid dine on one another—some scientists speculate that the squid may have accidentally swallowed a few parts of itself somehow.
15. The Smithsonian has two giant squid on display.
You can see them in the National Museum of Natural History’s Sant Ocean Hall. The pair represents both sexes—here’s a quick look at their 25-foot female (it was probably 36 feet while alive):
16. Their brains are donut-shaped.
But that’s not the weird part. What’s truly bizarre (at least from our mammal-centric perspective) is the fact that its esophagus passes through the hole in the middle of its brain. Giant squids have to be really careful while swallowing, because if a given meal isn’t broken down into small pieces first, it can rub against the brain and cause damage.
17. Before 2004, nobody had ever snapped any pictures of a live one …
History was made by residents of the Ogasawara Islands (located 600 miles south of Japan) on September 30, 2004. Using a line baited with shrimp, zoologist Tsunemi Kubodera and whale-watcher Kyochi Mori attracted an Architeuthis about 2950 feet beneath their vessel. Five hundred still images were then snapped by a submerged camera before the squid took off—leaving behind an 18-foot severed tentacle.
18. … And the world’s first giant squid video didn’t arrive until 2006.
Kubodera would top himself that year when his crew videotaped a young female as they dragged her up to the surface. “We believe this is the first time anyone has successfully filmed a giant squid that was alive,” he said. “Now that we know where to find them, we think we can be more successful at studying them in the future.” Sadly, Kubodera’s prize died during the ordeal.
19. Jellyfish help Architeuthis hunt.
They say the enemy of your enemy is your friend. Certain jellyfish are bioluminescent, which means that they can light themselves up and illuminate the ocean’s inky depths. Predators like giant squid eat many of the fish that hunt jellyfish. So, if a bioluminescent jelly finds itself under attack, it can issue a cry for help by flashing a distress signal, in the hopes that it might attract an even larger carnivore and scare off its assailant. That was the theory behind luring the giant squid with an electronic jellyfish, as seen in the recent NOAA video.
20. It’s not the only monster-sized squid out there.
Meet Mesonychoteuthis hamiltoni, better known as the colossal squid. Though Architeuthis probably exceeds it length-wise, M. hamiltoni is heavier on average, has even bigger eyeballs, and wields swiveling hooks on its tentacles. This isn't a creature you’d want to mess with.