The first view was of a life stage
The colossal squid filmed near the South Sandwich Islands in March 2025 was about 30 centimeters long. Its importance had little to do with size: researchers could finally watch a confirmed living individual at depth, in its own environment. The animal was a juvenile, with a largely transparent body. A species known from heavy specimens suddenly had a much smaller living face.
How does an animal survive the stages before it becomes enormous? The recording gives us posture and movement at one depth; preserved specimens reveal anatomy; studies of related squid suggest mechanisms to investigate. Those records can inform one another, but they do not describe the same animal under the same conditions.
What the camera actually established
Schmidt Ocean Institute’s encounter report places the sighting on March 9, 2025, at 600 meters depth. The remotely operated vehicle SuBastian, deployed from Falkor (too) during an Ocean Census expedition, recorded it. The announcement followed on April 15.
Specialists Kat Bolstad and Aaron Evans checked the imagery. Hooks midway along the eight arms helped distinguish Mesonychoteuthis hamiltoni from the similar-looking glacial glass squid. Transparency and hooks on the two longer tentacles alone would not separate the two. Identification depended on a particular anatomical arrangement, visible well enough for specialists to assess.
“First footage” needs its qualifier. Dying adults had already been filmed following encounters with fishing gear. This was the first confirmed observation of a living colossal squid at depth in its natural habitat. It did not mark the species’ discovery, and a juvenile in a camera’s lights did not reveal adult behavior.
The museum giant is a different kind of record
Te Papa’s centenary account connects the animal’s scientific naming in 1925 with the specimens studied since. Its displayed female was collected in the Ross Sea in 2007; the museum lists her at 4.2 meters and 495 kilograms. These are measurements of one specimen, rather than a universal adult size or a demonstrated upper limit.
The museum describes fixed hooks along the arms and swiveling hooks on the tentacle clubs. Those details explain why small gripping structures can carry more identification value than an overall impression of size.
Giant squid and colossal squid are also distinct, only distantly related animals. A photograph of one cannot fill gaps in the other’s life history. Our article on colossal squid eyes follows a related distinction: measured anatomy can be secure even while its evolutionary explanation remains debated.
See-through does not mean invisible
Open water offers few places to hide. A transparent body can reduce the dark outline a predator sees against faint light from above. Direct illumination creates another problem: transparent tissue can reflect an incoming beam.
Duke’s account of camouflage experiments explains this tradeoff using the octopus Japetella heathi and squid Onychoteuthis banksii. Under blue light, those animals rapidly activated pigments and became opaque. The result illustrates why transparency can work differently against silhouettes and biological searchlights.
Those experiments did not test the colossal squid. We should therefore use them to understand the optical problem, without assigning the same switching behavior to the juvenile in the video. Nor is a brightly lit animal on a research screen necessarily as conspicuous under the surrounding ocean’s normal illumination.
Floating without a gas balloon
Woods Hole Oceanographic Institution’s glass-squid overview describes buoyancy from ammonium-chloride-rich fluid, which is less dense than seawater. This provides a useful family-level explanation for how delicate squid can remain suspended without continuously swimming hard. The 2025 recording did not measure the juvenile’s internal chemistry.
The distinction becomes especially useful when reading general glass-squid facts. WHOI discusses particular smaller species, including Cranchia scabra. Its growth timing, defensive shapes and light-producing structures should not become a schedule or feature list for colossal squid. A family resemblance supports a question to investigate; it does not make every relative interchangeable.
A likely descent, rather than a tracked journey
A 2017 review of colossal squid biology reports that very small juveniles, below 40 millimeters in mantle length, occur mainly between the surface and 500 meters. Later juveniles are assumed to descend during development, potentially reaching 2,000 meters. Mantle length measures the main body, rather than the whole animal with its appendages.
This proposed developmental shift is called ontogenetic descent. It differs from an animal making a daily return trip between depths. The review also places colossal squid in a Southern Ocean food web, with remains recorded in numerous predators and evidence for feeding on fish and other squid.
The juvenile recorded at 600 meters adds a known location and a living body to that picture. It does not tell us its age, where it hatched or where it would go next. A life-stage label cannot supply a growth rate.
The observer is part of the encounter
A study of unobtrusive deep-sea camera platforms describes low-light cameras, red illumination and lures that imitate bioluminescence. The researchers recorded several deep-sea squid species, including giant squid, in the Wider Caribbean. Their methods addressed the difficulty of observing fast, alert animals with conventional equipment.
An empty dive therefore has several possible explanations: the route may sample the wrong water, the animal may be outside the camera’s field of view, or the observation method may affect the encounter. The camera study does not establish that every adult colossal squid avoids every vehicle, or that red light is invisible to this species. The same distinction matters in bigfin squid footage, where seeing an unusual posture is easier than establishing how it functions during feeding.
The next useful observation need not be a larger silhouette. Feeding footage could address prey capture; repeated sightings at known depths could test the proposed developmental descent. This juvenile supplies a reference for those comparisons: an identified animal, whole and moving, at a documented place and depth.
