The largest squid, in terms of length, is the giant squid . These enormous cephalopods can measure over 13 meters long and weigh nearly 270 kg .
However, in terms of weight, the largest squid (and, incidentally, the largest invertebrate) is the colossal squid . Colossal squid are nowhere near as long as giant squid, rarely exceeding 9 meters in length, but they are much heavier – some females can weigh up to 500 kg !
The largest octopus is smaller than the largest squid, but it is still enormous. The giant Pacific octopus can measure (including its tentacles) nearly 6 meters long and weigh around 50 kg .
I'm aware that there are legends of giant squid exceeding 20 meters in length, but since these sightings aren't scientifically documented, I've ignored them. The internet is rife with misinformation, sometimes unintentional, often due to exaggeration.