Navy seals. (Life/Animal Behavior).

He may have fish-breath, but that won't stop the U.S. military's new secret agent in the Persian Gulf. Zak, a 375-pound California sea lion (Zalophus californianus), is one of an elite cadre of 20 sea lions and 70 dolphins trained by the Navy to sleuth out people and objects underwater. Zak's mission: to nab suspicious divers near military ships or piers. "If there's somebody down there who shouldn't be, the sea lions will find him," says Navy spokesman Lt. J.G. Josh Frey.

Now in Bahrain, Zak--age 19--patrols the water, carrying a handcuff-like clamp attached to a rope in his strong jaws. When he spies an intruder, he sneaks up from behind. Then, with a thrust of his powerful flippers, he closes in and snaps on the cuff. "You wouldn't know anything was there till you have the clamp on your leg," says Navy spokesman Tom Lapuzza. Sailors aboard the ship then reel in Zak's catch. If sea lions perform well in the Persian Gulf, the species could soon be deployed in U.S. harbors.

Sea lions, seals, and walruses belong to the pinniped family. In nature, pinnipeds spend a lot of time hunting fish. "Sea lions have to find fish to survive," says sea-lion trainer Jenifer Hurley at California State University in Monterey. In exchange for work, trainers reward sea lions with fish.

With his extraordinary underwater vision and hearing, wouldn't Zak rather chase fish than bad guys? Actually, no. "Catching fish isn't that easy," Hurley says. "It's a lot easier to be fed from a human than to hunt in the open ocean." Talk about a win-win situation.