This Is Why… penguins can fly!

(but the landing isn’t pretty)

Emperor penguins are portly creatures. That’s a good thing – all that bulk is a great way to stay warm when it’s -30°C. The downside (pun intended) is that they are not the most nimble of birds when moving around on the ground, especially since they have relatively short hind limbs. Nor can they fly (in the conventional sense), so it would seem that penguins drew the short straw in the birdly attributes department. But, given that their food and their predators are in the water, being nimble swimmers is really the key to their survival.

If you’ve ever been to a zoo or aquarium, you’ve probably been transfixed by the speed of these amazing creatures as they zig-zag through the water. Their cruising swim speeds are about 2 m/s, similar to the steady pace of about 3 m/s of a typical marathon runner. Obviously they are capable of much faster bursts to catch prey or deke out a predator, but how do they get out of the water in a hurry? If there’s a pod of hungry orca on their tail, the safest place is on the ice surface above. They need to be able to leap out and clear the edge convincingly so they don’t slip back into waiting jaws below. Awkwardly clamouring out at the water’s edge is just not going to cut it.

Bubbles to the rescue! When at the surface, penguins often preen and groom, filling up their plumage with air. When they dive, that air is compressed by the increasing pressure. If they want to escape the water in a hurry, they dive to a depth of about 15 to 20 m and squeeze that compressed air tightly against themselves. When the penguins start to climb, the air wants to expand again, but it can’t. The result? Tiny bubbles of air sneak out through the mesh of feathers all around the penguin, creating a column of bubbles for the tuxedo-wearing torpedoes to rocket through.

By creating a tiny air layer around itself, the penguin lessens the drag of the seawater, reaching launch speeds that are 3 to 4 times their regular cruising speeds. This is more than enough to beat the force of gravity as they leave the water, sending them flying through the air, bellyflopping to safety. Engineers have been experimenting with the use of microbubbles to reduce drag in the shipping industry since the 1970s, with modest success. Another example of the animal world applying physical principles more expertly than the human experts.

An amazing video from the fabulous National Geographic team can be found here:

Published by joanneomeara

Professor, Department of Physics, University of Guelph

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