The third class of mollusks is cephalopods. It includes the squid and nautiluses. The octopus on the front of this card is also a cephalopod.Cephalo means “head.” Cephalopods have tentacles around their heads instead of feet. The tentacles help them swim, walk, and capture prey. They all live in the ocean. They move by forcing water out of a siphon in one direction. This causes them to move in the opposite direction. The giant squid is the world’s largest invertebrate. It can grow to a length of 18 meters and a weight of 900 kilograms. That’s longer than a school bus and probably weighs more than your whole class put together.