Architeuthis, the giant squid—like all other squid—jets through the water using a propulsion system in its mantle. Water flows in through openings in a kind of collar around the “neck,” expanding the mantle. The mantle contracts, the neck openings snap shut, and water jets out of the funnel, propelling the squid. By reversing the funnel, the squid can move in another direction, its long tentacles aimed toward prey. In all squid, impulses move swiftly along the largest nerve fibers in the animal kingdom, controlling millisecond muscle movements. The eye of the giant squid is the largest of any known animal, roughly the size of a human head. This side-view sketch shows one of the squid’s two feeding tentacles and four of its eight arms. The giant squid can reach 60 feet (18 meters) long with tentacles extended.