Penguins! – December 25, 2019
For all of you celebrating around the world, we wish you very happy holidays! For this Science Wednesday, we’re talking about penguins. Did you know that all penguin species live in the Southern Hemisphere? Indeed, they occupy four different continents: South America, Africa, Australia and, of course, Antarctica. Although their very ancient ancestors were flying birds, penguins have evolved as specialized divers and swimmers and have had their present form for the last 45 million years. Penguins’ wings are so small that they are called flippers instead.
Most birds’ bones are filled with air chambers and are therefore light in weight, making it easier for birds to take off into the air. Penguin bones do not have these air cavities and are therefore much heavier, making it easier for penguins to dive underwater. The penguin body, although bulky and awkward on land, is streamlined to minimize drag in the water. Penguins “fly,” just, underwater! Their flippers provide the power while their webbed feet, tucked in under their tail, are used for steering.
Finally, how do penguins stay warm in such extreme conditions? Unlike other birds which have feathers growing in lines with gaps of featherless skin in between, penguin feathers cover all the skin. Their densely packed feathers provide an impregnable coat that prevents water from reaching the skin. The feathers are short and stiff, with lots of down at the base. These dense feathers, together with a layer of blubber under the skin, do an excellent job of conserving penguins’ body heat, even in blizzards!
Image from expedition to Antarctica aboard the Nathaniel B. Palmer icebreaker, 2007. U.N. Horodyskyj