The first argument is about size: media reports often claim giant squid grow up to 18 metres (60 feet), but the largest verifiable giant squid was 12 metres long, according to National Geographic, which also says the biggest known giant squid was 12 metres long but the average length is 7.3 metres.

As of November 2026, Guinness World Records says a giant squid can reach at least 13 metres in length, most of it tentacles, with a mantle that reaches up to 2.25 meters, and it says the heaviest whole giant squid on record weighed about 220 kilograms (485 pounds).

A camera photographed a live giant squid off Japan on September 30, 2004, and that squid was about eight metres long, while the squid in the 2012 video was about three metres long, and the scientist Kubodera estimated the 2012 squid would have been eight metres long if it had been whole.

In 2016 a statistician, Charles Paxton, estimated that giant squid may plausibly reach 20 meters in total length, but this is a calculation, not a measured squid, and before Paxton, a check of more than 130 giant squid specimens found none longer than 13 meters.

Because eyeballs collapse and the head sags after a giant squid dies, scientists have to take some guesses when they measure them, and Guinness says the 1887 Lyall Bay report of 55 ft 2 in was most likely too long because the elastic tentacles were over-stretched.

Estimates of the depth range for giant squid vary: one museum page says specimens were caught at 400 to 800 meters, and another source says 300 to 1000 meters is not unrealistic, while catches by trawlers suggest a depth range of about 300 meters to 1 kilometer, and in a beak chemistry study of squid from stranded whales, the giant squid proved to be the deepest dweller of the species tested.

One idea is that young giant squid drift far as larvae and youngsters, while another is that adults stay close to home; scientists are still working out which it is, and the 2013 team reasoned that young giant squid living near the ocean surface must drift in currents around the globe, which could explain why one species spans the world.

In March 2013, scientists reported that DNA from giant squid around the world shows they are one species, and one science reference says probably only one species of giant squid is valid, a conclusion based on the 2013 DNA study.

In March 2025, scientists filmed a young colossal squid, about 30 centimetres long, in the deep sea, and it was a colossal squid, not a giant squid.

In July 2012 a team filmed a live giant squid in its deep-sea home off Japan, from a small submersible, and in June 2019 scientists filmed a giant squid in the Gulf of Mexico, the first one recorded in United States waters.

A female giant squid's eggs are fully developed and ready to be fertilised, though how she gets sperm is unclear, and a female also makes a huge number of tiny, whitish eggs.

Juvenile giant squid have been taken from the stomachs of deep-sea fishes, so they are part of the deep-sea food web, and sperm whales, the largest of the toothed whales, eat mostly squid.

As of November 2026, the IUCN Red List lists the giant squid as Least Concern, last assessed 28 April 2010, and scientists do not know how many there are.

Words to know

• verifiable: checkable
• statistician: number expert
• plausibly: believably
• larvae: baby forms
• colossal: huge