WASHINGTON (AP) _ A 7-foot sea creature with hooks on its arms, flashing blue-green lights and a donut-shaped brain may sound like a fish story; but it's real, and the Smithsonian has it on display.

It's Taningia danae, a deep-sea squid that's part of a new exhibit at the National Museum of Natural History.

''In Search of Giant Squids,'' opens Saturday, introducing visitors to proof that, in the words of researcher Mike Vecchione: ''Weird things actually exist.''

Vecchione is part of the museum's ''squid squad,'' a team of scientists that studies the eight-armed, two-tentacled mollusks and maintains a collection of 100,000 preserved squids and related sea creatures.

''In terms of its biology, the squid is far more interesting than any myth you can dream up,'' said Clyde F. E. Roper, curator of the exhibit.

Taningia alone may prove the point.

Living in the lightless depths of the ocean, more than 3,000 feet below the surface, Taningia can flash its lights like a pair of blue-green strobes mounted at the tips of two of its arms. The scientists refer to it as the world's largest flasher - a trick apparently used to warn off predators.

Who would eat an animal 7 feet long, weighing 135 pounds?

Whales, said Roper. ''Whales eat pretty much what they want,'' and studies of their stomach contents disclose that they often want squids.

Other sea animals eat smaller squids, as do people, though the exhibition tactfully refrains from any mention of fried calamari.

It's unlikely a person would tackle another squid on display at the museum. Architeuthis dux is 9 feet long and weighs 440 pounds. And she's a midget compared to others of her species, who can grow to 59 feet and weigh nearly a ton.

The squids on display, though not alive, are carefully preserved and lifelike, giving viewers a close look at the animal's size and structure. Nearby displays show their insides and a picture of Taningia shows it underwater with lights flashing when a button is pressed.

Squids are hard to keep alive in captivity, Roper explained. And even in the sea they live only a few years, with one reproductive cycle at the end of their life.

They are often confused with octopi; and while they are related, squids have two extra tentacles, often much longer than the other eight arms, that can be used as feeding arms to reach out and grasp prey.

Squids use jet-like propulsion to swim, ejecting water through a funnel that can be aimed to allow them to move suddenly in one direction or another. They have been clocked at 45 miles per hour.

Squids are also famed for their propensity to blow clouds of black ink into the water to confuse predators. But Vecchione says there's at least one weird variation on the theme - a deep water squid that squirts ink that is luminous.

Bacteria that live in the squid glow, and the animal ejects them in its ink, leaving a glowing cloud in the water as it escapes. Black ink wouldn't work in the deepest water, since there's no light there and everything is black anyway, Vecchione explains.