Giant squid live in every ocean on Earth but are particularly concentrated over the slopes leading up to continents and islands. They are rare in tropical and high polar regions. Giant squid live only in deep, cold water because their blood is incapable of carrying oxygen effectively at higher temperatures.
Giant squid weigh up to one ton and can grow up to 60 feet long. The largest part of that length are the feeding tentacles, which are longer than the rest of the body. Nonetheless, giant squid are the largest cephalopods alive and are possibly the largest invertebrate animals that have ever lived. They feed using their long tentacles, which are tipped with round suckers. The suckers themselves are lined with sharp chitin teeth to help grasp their prey, which include deep-sea fish and other species of deep-sea squid. The tentacles pull the prey to their eight arms, which in turn draw the prey to their sharp beaks for consumption.
To help cope with their dark deep-water environment, giant squids have the largest eyes of any animal. Each eye can be as large as a human head. They also have an unusually complex brain and nervous system. How these systems affect their behavior is unknown, since all knowledge of the species comes from examinations of dead specimens, as it hasn't been observed in its natural habitat.