Giant squid have the largest eye in the animal kingdom. At up to 10 inches in diameter, people often describe it as the size of a dinner plate -- or, in other words, as big as a human head. Here, National Museum of Natural History staffer Katie Velazco goes eye-to-eye with a preserved example from the Smithsonian's collection.

Why do they need such big eyes? The deep ocean is so dark that bigger eyes probably don't help the giant squids pinpoint and hunt small food. However, drawing in even a bit more light could help them see larger shadowy shifts in the depths -- like those produced by an enormous predator. A study published in March 2012 suggested that giant squids could detect a moving sperm whale from 394 feet (120 meters) with those big eyes.

Giant squid have more than just giant eyes. Learn about the giant squid's beak, suckers, and other over-sized body parts in this video with Smithsonian scientist Clyde Roper. Want a basic overview of the animal? Visit our Giant Squid section.