I've heard tales of octopuses and squids sinking ships. They live in salt water from the tropics to temperate zones. Both octopuses and squids are related to snails and other molluscs. Unlike snails, octopuses no longer have any remnant of a shell.
Squids possess a stiff structure known as a pen, that acts as a flexible backbone.
Their blood is this colour because they use an oxygen-carrying molecule in their blood that contains copper. Octopuses and squids have hard, parrot-like beaks. These are excellent for killing, and tearing pieces of flesh from their prey. Octopuses live in dens on the sea floor. Squids live in the open oceans.