Bigger Than the Giant Squid
Despite its fame, the giant squid (Architeuthis dux) is not the largest squid in the ocean. That title belongs to the colossal squid (Mesonychoteuthis hamiltoni) — a creature so large and so rarely encountered that science has been piecing together its biology from a handful of specimens, most of them found in the stomachs of sperm whales.
The colossal squid is the largest known invertebrate on Earth — not just the largest squid. Its mantle (body) alone can exceed 2.5 meters. Total length including tentacles is estimated at 10–14 meters for large females. Its eyes — the largest of any living animal — can reach 27 cm (nearly 11 inches) in diameter.
Anatomy: Built for the Deep
Several features distinguish the colossal squid from its giant cousin. Its tentacles are equipped with sharp, rotating hooks — not just suckers — that can swivel independently and grip prey with mechanical force. These hooks are so distinctive that even partial remains found in sperm whale stomachs can be identified by their shape alone.
The colossal squid’s eyes are almost certainly the most sophisticated visual organs in the deep ocean. At 27 cm across, they can detect the faint bioluminescence of other animals and the minimal light that filters down from the surface at extreme depths — giving the squid a significant advantage in near-total darkness.
Where Does the Colossal Squid Live?
The colossal squid lives primarily in Antarctic and Sub-Antarctic waters, at depths ranging from 1,000 to 2,200 meters. It is a deep-water inhabitant of the Southern Ocean, where cold, oxygen-rich water supports the dense prey populations it requires. Its primary prey is Patagonian toothfish and other large mesopelagic fish.
How Do We Know Anything About It?
The colossal squid is known almost entirely from incidental captures and stomach contents. The first live specimen was not photographed until 2007, when a New Zealand fishing vessel hauled up a juvenile in Antarctic waters. The largest intact specimen ever recovered — a female captured in 2007 — weighed 495 kg (1,091 lbs) and is preserved at the Museum of New Zealand Te Papa Tongarewa in Wellington.
Sperm whale stomachs have provided most of our knowledge. Colossal squid beaks (which do not digest easily) are routinely found in sperm whales, and the circular scars left by the squid’s rotating hooks can be seen on the skin of sperm whales — evidence of battles between the two species at extreme depths.
Frequently Asked Questions
Is the colossal squid bigger than the giant squid?
By mass, yes. The colossal squid is significantly heavier and has a larger mantle than the giant squid, though giant squids may have longer tentacles. The colossal squid is the largest invertebrate by weight.
Has anyone ever seen a live colossal squid?
Rarely. The first live specimen was photographed in 2007. Most knowledge of the species comes from dead specimens caught in fishing nets or recovered from sperm whale stomachs.