Colossal squid filmed alive for the first time in the deep sea

A creature once known only from the bellies of whales finally makes its own debut. In a discovery that has stirred wonder across the marine biology world, a colossal squid—long considered a near-mythical creature—has been filmed alive for the very first time in its natural habitat, deep in the frigid waters off the South Sandwich Islands in the South Atlantic Ocean.

Spotted on 9 March by researchers aboard the Falkor (too), a vessel operated by the Schmidt Ocean Institute, the squid was a juvenile, measuring around 30 centimetres in length. Still, it bore the unmistakable features of Mesonychoteuthis hamiltoni—hooks on its arms, a translucent body and the ghostly grace of a creature few thought they’d ever see alive.

“This is the first confirmed footage of the colossal squid at home in the deep sea,” said Dr Kat Bolstad, a cephalopod biologist at the Auckland University of Technology, who helped verify the sighting.

A ghost from the deep

The colossal squid is the heaviest invertebrate on Earth, capable of growing up to 7 metres long and weighing as much as 500 kilograms. But until now, all evidence of its existence came from scattered remains—fragments of arms found in whale stomachs, or dead animals hauled up accidentally by fishing boats.

It’s been 100 years since scientists first described the species in 1925, based on two arm crowns recovered from a sperm whale off the Shetland Islands. In the decades since, occasional specimens have surfaced, but always lifeless—drifting ashore, trapped in nets, or dying on fishing lines. Never before had anyone filmed one alive in the depths of the ocean it calls home.

“It’s exciting to see the first in situ footage of a juvenile colossal and humbling to think that they have no idea that humans exist,” said Dr Bolstad.

An encounter born of patience and precision

The footage was captured using SuBastian, a remote-controlled submersible deployed as part of a 35-day expedition led by University of Essex marine biologist Dr Michelle Taylor.

The mission—conducted in partnership with Ocean Census, an initiative to discover unknown species—had set out to explore life in some of the planet’s least-studied waters. The squid appeared unexpectedly at a depth of 600 metres. “We didn’t know what it was at first,” said Dr Taylor. “But it was beautiful and unusual, so we made sure to record it.”

Moments like these are hard to come by. “They know we are there long before we know they are there,” Bolstad explained. “They are actively avoiding us.”

It wasn’t until after the expedition, when Bolstad returned from her own Antarctic mission, that she was sent the video for analysis. “Pretty much as soon as I saw the footage, I knew there was a good chance,” she said.

A teenager from the twilight zone

Though small, the squid was not a newborn. Experts believe it was a juvenile—midway through development. “It’s not the giant animal we’d expect the colossal squid to be,” said Aaron Evans, an independent scientist and glass squid expert. “It’s not a baby either. We can think of this as maybe a teenage squid.”

Juveniles often linger in shallower twilight zones of the ocean before descending to greater depths as they mature. Their near-transparent bodies offer camouflage, shielding them from predators. As they grow, they develop pigmentation and their glassy forms give way to reddish, opaque bodies built for life in the deep.

Hooks, eyes and survival

The colossal squid is armed with some of the most remarkable evolutionary traits in the animal kingdom. Each of its eight arms features large, fixed hooks; its two longer tentacles boast rotating ones. Its eyes are the largest of any animal on Earth—larger than a basketball—designed to spot predators like sperm whales, which can dive to depths of two kilometres in search of prey.

Despite their fearsome adaptations, these squids are not apex predators. Penguins, elephant seals and other fish are known to hunt their juveniles. Sperm whales and sleeper sharks target both young and adult squids, and bears the scars to prove it.

“The fact that we can now observe them as living creatures, and not just as remains, opens up so many possibilities for understanding their lives,” said Bolstad.

Beyond myth: Science meets mystery

The Natural History Museum has long called the colossal squid a creature that straddles “the line between legend and reality.” That sentiment echoed again when footage from SuBastian was reviewed and confirmed.

Christine Huffard, a biologist at the Monterey Bay Aquarium Research Institute, praised the finding. “These exploratory missions have tremendous value,” she said. Her own chance observation of octopuses walking bipedally on the sea floor has since helped develop technologies in soft robotics. Discoveries like this one could inform decisions on deep-sea mining and marine conservation.

“We need to understand where these animals live, how long they live, where they travel to mate or spawn,” Huffard said. “This kind of footage helps.”

And it’s not just about colossal squid. In January, scientists from the same vessel filmed a glacial glass squid—another first. “The first sighting of two different squids on back-to-back expeditions is remarkable,” said Dr Jyotika Virmani, executive director of the Schmidt Ocean Institute. “It shows how little we have seen of the magnificent inhabitants of the Southern Ocean.”

A different kind of giant

For Bolstad, there’s something poetic about the fact that the first live footage of a colossal squid wasn’t of a full-grown behemoth—"an enormous, hook-wielding leviathan"—but of a delicate, transparent juvenile that looked more like a floating glass sculpture than a sea monster.

“I actually love that this is our first glimpse of what will become a true giant,” she said.

Even a century after its discovery, the colossal squid is still writing its story. And for the first time, we get to see it—not as fragments, not as folklore, but as it truly is: alive, drifting silently in the deep.