Dec 11 2010
There are many answers to this question but one of the most intriguing was formulated when paleontologists discovered the complete skeleton, including feathers, of an extinct penguin dubbed Inkayacu paracasensis, the “Water King.”
When the Water King’s skeleton was found on the Pacific coast of Peru in 2008, scientists had just recently discovered they could determine the color of fossil animals by examining the size and shape of cellular structures called melanosomes. Armed with this information they figured out that Inkayacu paracasensis was gray above and reddish-brown below.
On a skeletal basis he looked just like a penguin though at five feet long he was larger than any alive today. By comparison the largest living penguin, the Emperor Penguin, is about four feet long.
But the Water King probably couldn’t swim as well as today’s penguins. Scientists theorized that this was because he wasn’t black.
Black pigment, called melanin, provides strength to the structures it colors. For penguins the structures requiring the most strength are their wings because they use them to literally fly through water. Water is 800 times denser than air so flying underwater is a very strenuous activity.
The Water King was gray, today’s penguins are black. Are modern penguins black because melanin gave them stronger wings? Maybe.
And why are penguins half white? Perhaps because they’re better camouflaged underwater when their bellies are white.
(Illustration by Katie Browne/U.T. Austin, linked from Science Now. Click on the illustration to see the original in context.)