Whale of a mystery solved? How they got so big
Washington – Scientists believe they have responded to a whale of a mystery: how the creatures of the ocean have risen so much and so fast.
There are a few million years, the largest whales, on average, perhaps 4.5 m long. That’s fine, but you can always keep a fossil skull in both hands.
Then, apparently during the night, a type of whale – the toothless Baleens – became huge. Modern blue whales reach 30m, the largest creatures to date on Earth. His skull is now larger than a minivan and could possibly contain more than five people inside, according to the researchers.
“We’re really living in the time of the giants,” said study co-author Nicholas Pyenson, the Smithsonian Natural History Museum. “Why then?”
And it happened “in an evolutionary wink,” so it’s hard to understand what happened, said Graham Slater at the University of Chicago, lead author of the study in Tuesday’s rehearsal Real Sociedad B.
Their study suggests an answer: periods of ice in the 3 to 5 million years began, the oceans change and food supply of whales.
The researchers used the fossil record of small whales to create a family tree of fin whales – including blue whales, Bosseaux and whales. Using computer simulations and knowledge of how evolution works, they began to fill the gaps between small whales and the ultra-large modern version.
They have entered a period where whales have become huge and the smallest whale species have disappeared somewhere in between a few hundred years and 4.5 million years.
They found that when the size changes began, the poles were colder, ice diffusion and the water flow in the oceans has changed, and the winds have changed. Slater and Pyenson said that the cold water fell deep and approached the equatorial line and finally bubbled in places rich with small fish and other small creatures that the whales eat.
Before that, food whales spread relatively easy to obtain. Now, they are giant buffets amidst hundreds of miles of deserted whale food. That’s why you can see many summer whales in California’s Monterey Bay, Slater said.
Bearded whales, which have no teeth, eat a lot of ocean, filter the water and eat the captured animals. Toothed whales, such as sperm, game fish or individual squid, so that changes in the ocean that made food are less evenly distributed do not affect much. But whale whales hunt banks of fish or krill swarms, Pyenson said.
“If you are a whale, the simplest way to enjoy the dense but few resources available is to become great,” said M. Slater. “If you’re tall, you can get essentially more miles per gallon.”
Bearded whales have risen from 4.5m to 30m or so at the same time humans evolved, he said.
Olivier Lambert at the Royal Belgian Institute of Natural Sciences, which was not part of the study, calls it “a really convincing scenario.” But he said the lack of fossils at certain periods of time is a problem.
Little by little, as the oceans are artificially distant climate change, the seas look more like whales are smaller and have more difficulty surviving, said Slater and others.