Six hundred meters below the surface of the southern Atlantic, in water just above freezing, a remotely operated vehicle caught something on camera that no human had ever recorded before: a living colossal squid. The animal was small, just 30 cm long, its body almost entirely transparent. It drifted in the blackness near the South Sandwich Islands on March 9, 2025, apparently unbothered by the lights of the machine watching it. More than a century after science first put a name to the species, this was the first confirmed footage of one alive in the open ocean.
A century-long blind spot, closed in seconds
The colossal squid, Mesonychoteuthis hamiltoni, was formally described by British zoologist Guy Coburn Robson in 1925, based on specimens pulled from the stomachs of sperm whales in Antarctic waters. His taxonomic paper, published in the Annals and Magazine of Natural History, established the species as the largest known invertebrate by mass. Adults are estimated to reach mantle lengths of up to 4 meters and weigh as much as 500 kilograms. Their eyes, the size of dinner plates, are the largest in the animal kingdom.
Yet for all its superlatives, the colossal squid has been a ghost. Every specimen studied by scientists arrived dead or dying, hauled up as bycatch in deep-sea toothfish fisheries or carved from the bellies of sperm whales. No researcher had ever observed one swimming freely in its own habitat. That changed during a University of Essex expedition aboard the research vessel Falkor (too), which deployed the ROV SuBastian, a deep-diving vehicle operated by the Schmidt Ocean Institute, to survey deep-sea ecosystems around the South Sandwich Islands.
According to the University of Essex, the ROV encountered the juvenile squid at 600 meters depth. The team did not rush to announce the find. Instead, they sent the footage to Kat Bolstad, a cephalopod taxonomist at Auckland University of Technology and one of the world’s foremost authorities on deep-sea squid. Bolstad confirmed the species identification before the material was made public, as reported by the Associated Press. A separate institutional release via EurekAlert corroborated the details.
Why a 30 cm squid matters
At 30 cm, this juvenile is a fraction of the size it could eventually reach. Its near-total transparency, visible in the footage, is a survival adaptation: in the dim twilight zone between 200 and 1,000 meters, a see-through body is effectively invisible to predators hunting by silhouette. That same transparency helped Bolstad confirm the identification, because the internal anatomy, including the distinctive rotating hooks on the tentacle clubs that set colossal squid apart from their giant squid cousins, was visible through the skin.
The distinction between colossal and giant squid trips up many readers. The giant squid, Architeuthis dux, is longer but lighter, built like a whip. The colossal squid is heavier and more muscular, built like a barrel. Giant squid were first filmed alive in 2004 by Japanese researchers and again in 2012 in the deep Pacific. The colossal squid has taken two more decades to yield its first living images, largely because it inhabits some of the most remote and inhospitable waters on Earth: the deep Southern Ocean surrounding Antarctica.
The South Sandwich Islands, where the encounter took place, are a chain of volcanic peaks rising from the floor of the southern Atlantic, east of the tip of South America. The surrounding waters are rich in nutrients and support large populations of krill, fish, and the predators that feed on them, including sperm whales. That these waters also harbor juvenile colossal squid is not surprising to biologists, but confirming it with video evidence anchors what was previously an assumption.
What the footage cannot tell us
A single encounter, however historic, has sharp limits. The footage shows one juvenile at one depth on one day. It cannot reveal how many colossal squid live in these waters, how fast they grow, what they eat at this life stage, or whether their range is shifting as ocean temperatures change. Almost everything known about the species’ life cycle still comes from dead specimens, and the growth trajectory from a 30 cm juvenile to a 4-meter adult has never been directly tracked.
Adult behavior remains almost entirely a mystery. The few whole adults that have been studied were recovered from fishing nets or whale stomachs, often badly damaged. Whether adults occupy the same depth range as this juvenile, or descend to deeper, colder layers as they mature, is unknown. Their hunting strategies, reproductive habits, and lifespan are inferred from anatomy and chemical analysis of tissue, not from observation.
The expedition may have collected additional environmental and biological data that could begin to fill some of these gaps, but as of June 2026, detailed scientific results beyond the initial announcements have not yet been published in peer-reviewed literature. Until they are, the footage serves as a proof of concept: colossal squid can be found and filmed alive, and the technology and expedition planning exist to do it again.
From legend to repeatable observation
For marine biologists, the real value of this footage is not the spectacle but the precedent. Every previous attempt to understand the colossal squid relied on specimens that had already lost their color, their posture, and their behavior by the time a scientist examined them. Now there is a reference point: a living animal at a known depth, in a known location, displaying a known life stage. Future expeditions can return to these coordinates, deploy ROVs at similar depths, and test whether the encounter was a one-off or a window into a regularly occupied habitat.
The broader pattern in deep-sea biology points toward the latter. As ROV technology improves and expedition funding grows, species that were once known only from trawl nets and stomach contents are increasingly being filmed in situ. The giant squid’s journey from myth to YouTube took centuries. The colossal squid’s journey from Robson’s 1925 description to confirmed live footage took just over 100 years. The next step, repeated observations across seasons, depths, and life stages, will determine whether this animal can finally be studied as a living species rather than a collection of preserved parts.
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*This article was researched with the help of AI, with human editors creating the final content.
