A colossal squid was filmed alive for the first time, 600 metres down

For a century, the colossal squid existed to science mainly as scraps: beaks pulled from whale stomachs, tentacle fragments hauled up in fishing nets, never a living animal in its own environment. That changed when the remotely operated vehicle SuBastian filmed a 30-centimetre juvenile swimming freely 600 metres down in the South Atlantic, the first confirmed footage of a live colossal squid anywhere. The animal was small enough to fit in two hands, a strange first glimpse of a species that can eventually grow into the heaviest invertebrate on the planet.

The footage came from a 35-day expedition near the remote South Sandwich Islands, run by Schmidt Ocean Institute alongside the Nippon Foundation-Nekton Ocean Census program and a University of Plymouth-led partnership studying the surrounding seafloor. Crews aboard the research vessel Falkor (too) had spent weeks surveying deep water for undiscovered marine life when the ROV’s cameras picked up the translucent juvenile drifting in open water, its distinctive hooked tentacles trailing behind it.

Why a Century Passed Without a Sighting

Colossal squid live at depths and in waters around Antarctica that make sustained observation extraordinarily difficult, and unlike their better-known relative the giant squid, they rarely wash ashore or turn up snagged on fishing lines in recognizable condition. Most of what scientists knew before this footage came from partially digested remains recovered from the stomachs of sperm whales and seabirds, or from squid hooked incidentally as bycatch by toothfish trawlers working the Southern Ocean.

Those secondhand sources could establish that the species existed and roughly how large it could grow, but they revealed almost nothing about how a colossal squid moves, hunts or behaves in the water column. A live animal on camera, however young, closed a gap in basic natural history that indirect evidence never could.

A Juvenile a Fraction of Its Adult Size

The squid filmed at 600 metres measured about 30 centimetres, roughly the length of a housecat, yet adult colossal squid are estimated to reach seven metres and weigh as much as 500 kilograms — figures that make the species the heaviest invertebrate known to exist. Reaching that size appears to take years of growth in some of the coldest, least-accessible water on Earth, which is part of why encounters with fully grown adults remain almost entirely limited to carcasses and partial remains rather than live sightings. Even the largest confirmed remains, recovered from fishing boats and whale strandings, have offered scientists no data on how the animal actually swims, feeds or reacts to a predator, since a dead or dying specimen behaves nothing like a live one on camera.

Kat Bolstad, a squid biologist at the Auckland University of Technology who helped confirm the footage’s identification, said the discovery let researchers “introduce the live colossal squid to the world as this beautiful, little, delicate animal,” a description that stands in sharp contrast to the species’ reputation, built almost entirely on the size of adult remains, as a deep-sea giant.

What the Footage Actually Shows

In the video, the juvenile hangs nearly motionless in the water column, its body almost see-through except for organs visible beneath the mantle, before drifting away from the ROV’s lights. Bolstad noted separately that the animal showed no apparent awareness of the machine observing it, remarking that it was “humbling to think that they have no idea that humans exist,” a reminder of how little contact the species has ever had with the surface world.

Michelle Taylor, the expedition’s chief scientist and a professor at the University of Essex, called the sighting “a once-in-a-lifetime situation,” noting that this class of discovery does not come along often even on expeditions specifically built to find undocumented deep-sea life.

An Ocean Still Producing Firsts

The same broader expedition series also captured the first confirmed footage of a separate species, the glacial glass squid, during an earlier leg near Antarctica, suggesting the Southern Ocean’s deep water still holds animals that have never been recorded alive despite decades of fishing and research activity in the region. Jyotika Virmani, Schmidt Ocean Institute’s executive director, said such moments are a reminder that the ocean “is brimming with mysteries yet to be solved.”

Researchers involved in the expedition say future dives will focus on locating a larger juvenile or sub-adult colossal squid, since a live look at the species partway through its growth toward seven metres would answer questions about its hunting behavior that the smallest juveniles cannot. The 35-day expedition that produced the footage was built around exactly that kind of open-ended search, with Ocean Census scientists surveying stretches of the South Sandwich Trench that had never been examined by a deep-diving ROV before, and cataloguing dozens of other species along the way that had never been recorded alive in the region.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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