Giant Squid vs Colossal Squid: Size and Key Differences

Key differences at a glance

The giant squid (Architeuthis dux) and the colossal squid (Mesonychoteuthis hamiltoni) are the two largest invertebrates alive, and both live in the deep sea, both have eyes as big as dinner plates, and both are eaten by sperm whales. Beyond that they are quite different animals from different families.

• Shape: the giant squid is slender, with long arms and extremely long tentacles; the colossal squid has a broad, heavy body and shorter limbs.
• Weapons: the giant squid has toothed suckers only; the colossal squid adds sharp hooks.
• Home: the giant squid lives in oceans worldwide; the colossal squid lives in the Southern Ocean.
• Knowledge: hundreds of giant squid specimens are known, but only about a dozen complete colossal squid had been recorded by 2015.

Which is bigger: length vs weight

Length favors the giant squid. Most adults measure 7.5–10.5 m (25–35 ft) from fins to tentacle tips, and the largest females are estimated at 12–13 m (39–43 ft). Most of that length is the two thin, elastic feeding tentacles, so a giant squid weighs only a few hundred kilograms: about 275 kg (606 lb) for the largest females and 150 kg (330 lb) for males.

Weight favors the colossal squid. The largest specimen ever examined, a female caught in the Ross Sea off Antarctica in February 2007, weighed 495 kg (1,091 lb), making it the heaviest invertebrate on record. After it was thawed, its mantle measured about 2.5 m (8.2 ft) but its total length only about 4.2 m (14 ft), probably because the tentacles had shrunk after death. Its beak was smaller than some colossal squid beaks found in sperm whale stomachs, so even bigger animals exist; estimates based on those beaks reach 600–700 kg (1,300–1,500 lb).

In short, if you laid the two side by side, the giant squid would stretch further, but the colossal squid would outweigh it by nearly two to one. The full set of giant squid measurements is in how big is a giant squid?

Hooks vs suckers

The easiest way to tell the two apart is to look at the arms. Both squid have eight arms and two longer feeding tentacles lined with suckers. In the giant squid, each sucker is a small cup on a stalk, 2–5 cm (0.8–2 in) across, edged with a ring of sharp, finely serrated teeth made of chitin. These rings grip prey and leave circular scars on the skin of sperm whales.

The colossal squid has suckers too, but its arms and tentacle clubs also carry hooks: some can swivel and others have three points. It is the only member of its family, the glass squids, to have hooks at all. Sperm whales in the Antarctic often carry long scratch marks that are thought to come from colossal squid hooks.

Eyes and beaks

Both squid have enormous eyes, the largest known in any living animal. The giant squid’s eyes reach at least 27 cm (11 in) across, with a pupil about 9 cm (3.5 in) wide. The eye of the 2007 colossal squid measured about 27 cm (11 in), with a lens about 12 cm (4.7 in) across, but the specimen was partly collapsed, and scientists think the eye was larger in life. The colossal squid’s eyes also carry light-producing organs called photophores.

The colossal squid also has the bigger beak, the largest of any known squid. Because beaks are hard and indigestible, they survive in the stomachs of predators, and scientists can identify both species and estimate their size from beaks alone.

Where do they live?

The giant squid lives in all the world’s oceans, usually 300–1,000 m (1,000–3,300 ft) deep over continental and island slopes. Most specimens come from temperate waters such as the North Atlantic, southern Africa, Japan, New Zealand and Australia, and it is rare near the poles.

The colossal squid is a creature of the cold Southern Ocean around Antarctica, with its range reaching north toward southern South America, South Africa and the southern tip of New Zealand. Young colossal squid are found in the upper 500 m (1,600 ft), and older ones live deeper. The two species may meet at the northern edge of the colossal squid’s range, but around Antarctica itself the colossal squid is the only giant.

How do they hunt and what do they eat?

The giant squid eats deep-sea fish, such as orange roughy, and other squid. Photographs taken in 2004 showed one attacking a baited line, which suggests it actively hunts rather than drifting and waiting for food.

The colossal squid seems to be a slower, ambush predator. Calculations of its energy needs suggest that its metabolism is very slow, and one estimate suggests that a 500 kg (1,100 lb) adult may need only about 30 g (1 oz) of food a day. It eats fish such as lanternfish and Antarctic toothfish, as well as other squid. Of about 8,000 Antarctic toothfish brought aboard by fishing vessels between 2011 and 2014, 71 showed wounds from colossal squid attacks.

Sperm whales: a shared predator

Both giant squid hunt in the dark, but both are hunted in turn. The main predator of each is the sperm whale, which dives deep to catch squid. In the Antarctic, colossal squid beaks make up about 14 percent of the squid beaks found in sperm whale stomachs, but because each colossal squid is so heavy, they are thought to supply most of the squid biomass those whales eat. Southern sleeper sharks also eat both species, and young colossal squid are taken by beaked whales, elephant seals, toothfish and even albatrosses.

Discovery and first footage

The giant squid was named in 1857 and is now known from about 700 specimens, many of them stranded or caught by accident in deep-sea trawls. It was first photographed alive in the deep in 2004 and first filmed in its natural habitat in 2012, both off Japan, as told in has anyone filmed a live giant squid?

The colossal squid was described only in 1925, from two arm crowns found in a sperm whale’s stomach. A complete animal was not caught until 1981, and the record 495 kg (1,091 lb) female of 2007 is now displayed at the Museum of New Zealand Te Papa Tongarewa in Wellington. The first confirmed video of a living colossal squid, a juvenile only about 30 cm (12 in) long, was recorded on 9 March 2025 by a remotely operated vehicle near the South Sandwich Islands at about 600 m (2,000 ft). Both species are listed as Least Concern by the IUCN, and both rank among the largest animals in the world.