Colossal squids are not extinct. These massive invertebrates continue to inhabit the deep, cold waters of the Southern Ocean, largely unseen by humans. Their elusive nature and the challenges of exploring their extreme habitat contribute to the widespread misconception that they might no longer exist. While direct observations are rare, scientific evidence confirms their ongoing presence in our oceans.
Unveiling the Colossal Squid
The colossal squid, known scientifically as Mesonychoteuthis hamiltoni, stands as the largest squid species in terms of mass, with confirmed specimens weighing up to 495 kilograms, and estimates for larger individuals reaching 600 to 700 kilograms. This makes it significantly heavier than the giant squid, despite often being shorter in overall length.
A distinctive feature of the colossal squid is its eyes, which are the largest known in the animal kingdom, estimated to be between 27 and 40 centimeters in diameter. Its arms and tentacles are equipped with sharp, swiveling hooks, rather than just suckers, which are used for capturing prey. The species primarily resides in the circumpolar Southern Ocean, at depths ranging from 1,000 to 2,000 meters for adults. The first scientific description of Mesonychoteuthis hamiltoni in 1925 was based on arm fragments discovered in the stomach of a sperm whale.
Proof of Their Presence
Evidence of the colossal squid’s continued existence comes from several discoveries. In 1981, an immature female specimen was caught by a Soviet trawler in the Ross Sea. Another subadult female, weighing approximately 300 kilograms, was collected by a New Zealand longlining vessel in Antarctic waters in 2003.
In 2005, a notable event occurred when a live specimen, estimated between 150 and 200 kilograms, was captured at a depth of 1,625 meters and briefly filmed alive at the surface. The most complete and heaviest specimen to date was a female caught in the Ross Sea in February 2007 by New Zealand fishermen targeting Antarctic toothfish. This specimen weighed 495 kilograms and measured 4.2 meters in length and now resides at the Museum of New Zealand Te Papa Tongarewa. More recently, in March 2025, the Schmidt Ocean Institute captured the first confirmed video footage of a live juvenile colossal squid, measuring 30 centimeters, in its natural habitat at a depth of 600 meters in the South Atlantic Ocean.
Why They Remain a Mystery
Colossal squids remain largely mysterious due to the extreme conditions of their deep-sea habitat. They live at immense depths, where light is scarce and pressure is overwhelming. This environment poses significant challenges for human exploration. The vastness of the deep ocean means that much of it remains unexplored, making encounters with these elusive creatures exceptionally rare.
Their behavior also contributes to their enigmatic status, as they are believed to be solitary and may actively avoid the noise and bright lights of research vessels. Scientists rely on indirect methods to study them, such as examining the beaks and fragments found in the stomachs of their predators, primarily sperm whales and sleeper sharks. Accidental captures by deep-sea fishing vessels also yield specimens for study. Advances in deep-sea cameras and remotely operated vehicles are beginning to offer new opportunities for observing these animals in their natural environment.