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ming and diving, penguins use their flippers to “fly” through the water exactly the way other birds use their wings to fly through the air. They use their feet primarily to steer, just as flying birds use their tail feathers. When penguins want to swim somewhere fast, they porpoise—that is, they swim just below the surface, surfacing often to breathe and travel briefly through the air—rather like a flying fish—and then dive down again. More typically, penguins travel by making short, shallow dives that last for about 20 seconds. They then rest on the surface for another 20 seconds or so before diving again. Penguins average between 2 and 4 knots (4 and 8 kilometers) per hour when they are swimming in shallow dives. They can put on short bursts of speed of up to 6 knots (12 kilometers) per hour when por- poising to pursue prey or evade a predator. Penguins dive to find the small fish, squid, and krill (tiny, shrimplike creatures that teem in the cold waters of the Antarctic region) that are their chief foods. All penguins dive surprisingly deep and can stay under- water for a long time, up to minutes on end. The Emperor penguin can stay below for as long as 18 minutes and reach a depth of more than 1,300 feet (400 meters). Medium-sized penguins such as the gentoo routinely dive

To move quickly through the water, penguins “porpoise.“ Just as dolphins and porpoises do, they swim just below the surface for a short time, leap forward out of the water to breathe, and then dive just below the surface again. They can reach speeds of up to 6 knots

(12 kilometers per hour) when porpoising.

Swimming and Diving Penguins are ungainly on land but amazingly graceful in the water, far more so than any of the other swimming and diving birds. Water- fowl, such as geese and ducks, swim on the surface by paddling with their webbed feet; diving birds, such as ducks and grebes, swim underwater by holding their wings close to their bodies and propelling themselves with their feet. Penguins take a totally different approach to swimming and diving. On the sur- face, they paddle along slowly by “rowing” with their flippers in shallow strokes. When swim-

At sea, penguins float much like ducks or geese. Unlike ducks or geese, which use their webbed feet to paddle along, penguins “row” with their flippers. These Adelie penguins are perfectly at home in ocean water so cold it is nearly frozen.

Clumsy and awkward on land, penguins are acrobatic and graceful underwater. Here a gentoo penguin “flies” through the water using its flippers for propulsion. The feet and tail are used to steer.

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