Science solves mystery of why whales got big so quickly

WASHINGTON: Scientists think they have answered a whale of a mystery: How the ocean creatures got so huge so quickly.

A few million years ago, the largest whales, averaged maybe 4.6m long. Then seemingly overnight, one type of whale – the toothless baleens – became huge. Modern blue whales get as big as 30m, the largest creatures ever on Earth. Its skull is now bigger than a minivan, researchers said.

“We really are living in the time of giants,” said study co-author Nicholas Pyenson of the Smithsonian Natural History Museum. “Why is that?”

And it happened “in the blink of an evolutionary eye”, which makes it harder to figure out what happened, said Graham Slater at the University of Chicago, lead author of the study in Tuesday’s Proceedings of the Royal Society B.

Their study has proposed an answer: Ice ages in the last three to five million years started it, changing the oceans and food supply for whales.

They concluded that when the size changes started, the poles got colder, ice expanded and the water circulation in the oceans changed and winds shifted. Slater and Pyenson said cold water went deep and moved closer to the equator and then eventually bubbled back up in patches rich with the small fish and other small critters that whales eat.

Before that, whale food was spread out, relatively easy to get at. Now, they are giant buffets amid hundreds of miles of whale food deserts.

“If you are a whale, the easiest way to take advantage of dense but sparsely available resources is to get big,” Slater said. “If you are big, you basically can get more miles to the gallon.” — AP