The Canadian Encyclopedia — neutral, cited, updated
July 26, 2026Sources cited
Canadianwire.
Canada’s encyclopedia & explainer
Home›Science & Nature›Marine biology›Colossal Squid
Science & Nature • Marine biology

Colossal Squid

The colossal squid (*Mesonychoteuthis hamiltoni*) is a large deep-sea squid found in the cold waters of the Southern Ocean.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The colossal squid (Mesonychoteuthis hamiltoni) is a large deep-sea squid found in the cold waters of the Southern Ocean. It is widely regarded as the heaviest living invertebrate, and it is also known for having the largest eyes of any animal.

Taxonomy and naming

The colossal squid is scientifically named Mesonychoteuthis hamiltoni and is the only recognized species in its genus. It is also known as the Antarctic squid or giant cranch squid.

Description

This squid is notable for its great mass, hooked tentacles, and exceptionally large eyes. Sources describe it as the heaviest living invertebrate and one of the largest squids by overall size.

Distribution and habitat

The species lives in cold, deep parts of the Southern Ocean around Antarctica. It is usually associated with depths from about 20 to 2,000 metres, and juveniles or displaced individuals may occur farther north.

Behaviour and diet

Colossal squid are believed to be slow-moving deep-sea predators that use their large eyes and hooked arms to detect and seize prey. Reported prey includes fish and other squid.

Conservation

The International Union for Conservation of Nature classifies the colossal squid as Least Concern. It is rarely observed, so its full population size and life history remain poorly understood.

Key facts

  • The colossal squid is a deep-sea cephalopod native to Antarctic and subantarctic waters.
  • It is considered either the largest or second-largest invertebrate in the world, depending on how it is measured against the giant squid.
  • The species has the largest known eyes of any animal, an adaptation to life in very low light.
  • It occurs circumpolarly in the Southern Ocean, with some individuals reaching waters near New Zealand.
  • It is listed as Least Concern by the IUCN.
🍁
Canadian context

Canadian ocean researchers and museums may study colossal squid as part of broader Antarctic and deep-sea biology, but the species is not native to Canada.

Frequently asked questions

What is a colossal squid?
A colossal squid is a large deep-sea squid species, Mesonychoteuthis hamiltoni, native to the Southern Ocean.
How big is a colossal squid?
Sources describe it as reaching roughly 10 to 14 metres in length and very heavy body mass, making it the heaviest living invertebrate.
Where do colossal squid live?
They live in cold waters of the Southern Ocean, usually at deep depths around Antarctica, with some records from waters near New Zealand.
Are colossal squid endangered?
No. The IUCN lists the species as Least Concern.
Why are colossal squid eyes so large?
Their huge eyes are thought to help them detect faint light and possibly predators in the deep ocean.
Is the colossal squid the same as the giant squid?
No. They are separate species, although both are among the largest squid and are sometimes confused in popular descriptions.

References

  1. Encyclopaedia Britannica — https://www.britannica.com/animal/colossal-squid
    Supports: Scientific name, habitat, size ranking, large eyes, range, conservation status
  2. Critter Squad — https://www.crittersquad.com/fact-sheets/colossal-squid-fact-sheet/
    Supports: Approximate size, hooks on tentacles, least concern status
  3. ThoughtCo — https://www.thoughtco.com/colossal-squid-facts-4154611
    Supports: Scientific name, size estimates, Southern Ocean distribution, least concern status
  4. Museum of New Zealand Te Papa Tongarewa — https://tepapa.govt.nz/digital-museum/explore-digital-museum/colossal-squid/life-and-habits-colossal-squid
    Supports: Habitat, range near New Zealand, depth
  5. BBC Future — https://www.bbc.com/future/article/20250130-colossal-squid-the-eerie-ambassador-from-the-abyss
    Supports: Heaviness, eye size, prey, depth, distinction from giant squid
  6. Oceana — https://oceana.org/marine-life/colossal-squid/
    Supports: Habitat, depth range, eye size, predation, conservation status