Whales Grew to Be So Gigantic - the Largest Animals That Ever Lived

Although we tend to think of dinosaurs as gigantic, they are not the biggest animals ever. In fact, the largest animal that ever lived on our planet at this time. It is a blue whale, a giant that can reach up to 100 feet (30m) in length and 200 tons (400,000 pounds) in weight. This huge beast, although in danger of extinction, is still wandering around our waters, with an estimated 10,000 to 25,000 live blue whales today. Now scientists have discovered why whales like the blue whale became so big.

An earlier theory explaining the gigantism of the whales saw its large size as a necessary adaptation to fight megasharks and other huge prehistoric animals. But scientists discovered that until about 4.5 million years ago the whales were kept at a moderate size, about 10 meters long. Then, near the beginning of the first Ice Age, they began to grow.

What happened? Researchers at the University of Chicago, Stanford University and the National Museum of Natural History of the Smithsonian studied fossils of 63 extinct whales to discover. They propose that the explanation lies in the radically changed diets of animals.

"We could imagine whales grew slowly over time, as if by chance, and maybe that might explain how these whales became so massive," said study co-author Graham Slater, who teaches geophysical sciences at the University from Chicago. "But our analyzes show that this idea does not hold up - the only way you can explain whales becoming the giants they are today is if something changed in the recent past that created an incentive to be a giant and did it Disadvantageous to be small. "

blue whale

A rare and endangered blue whale, one of at least four feeding 11 miles from Long Beach Harbor on the Catalina Canal, flows near the offshore oil rigs after a long dive on July 16, 2008 near Long Beach, California. (Photo by David McNew / Getty Images)
As glaciers grew during the Ice Age, their periods of "runoff" or melting in spring and summer threw nutrients into the ocean, allowing an explosion in the amount of tiny crustaceans called krill and other small animals they eat. Prior to this, whale food was available throughout the year, but the resulting climate change caused much of that supply to disappear.

Instead, the food was available in abundance seasonally and only in certain areas. This encouraged whales to grow faster and faster to find, consume and store food more efficiently. The reason the larger whales were preferred by evolution is that they could survive the long migrations needed to reach the next patch of food.

Fin whales can be 140,000 pounds. Whale whales tip the scale at 200,000 pounds. And the great mother of them all, the blue whale, can get a whopping 380,000 pounds - making it the largest animal that ever lived.

But while the whales have impressed us with their large size, people have wondered how they became so colossal.

In a study published Tuesday in the journal Proceedings of the Royal Society B, a team of researchers investigated gigantism in bearded whales, leaching food leaks that include blue whales, whale whales and whales. Marine mammals became relatively recent jumbo size, they found, only in the last 4.5 million years. The cause? A climate change that allowed the giants to overeat.


Baleen whales became large around the same time when the ice sheets began to cover the northern hemisphere. SilverbackFilms / BBC Credit
Whales have an interesting evolutionary history. They began as mammals that lived on land and with helmets about 50 million years ago. For several million years they developed fins and became sea creatures. Between about 20 million and 30 million years ago, some of these ancient whales developed the ability to filter food, which meant they could swallow tiny swarms of prey in a single gigantic swallow. But even with this feeding capacity, whales remained only moderately large for millions of years.

"But then suddenly - 'boom' - we see them as big as blue whales," said Nick Pyenson, curator of fossil marine mammals at the National Museum of Natural History at the Smithsonian Institution and author of the article. "It's like going whale-sized minivans to more than two auAnts around the same time, independently of each other. Beginning about 4.5 million years ago, giant blue whales were appearing in the oceans around the world alongside giant whales and giant whales. The researchers suspected that an environmental change occurred during that time which essentially caused whale whales to cluster. After some research, they found that this period of time coincided with the early beginnings of when the ice sheets were increasingly covering the Northern Hemisphere. Continue reading the main story Photo Baleen whales use their huge mouths to sift through krill and fish. Credit SilverbackFilms / BBC Glacier runoff would have washed away nutrients like iron in coastal waters and intense seasonal upwelling cycles would have caused cold water from deep underground to rise, bringing organic material to the surface. Taken together, these ecological effects brought large amounts of nutrients to water at specific times and places
, which had a cascading effect on the ocean food web. The zooplankton and krill groups would gather to revel in the nutrients. They would form dense patches that could stretch many kilometers long and wide and be more than 65 feet thick. The oceans became the giant buffets of whales. "Although they had the anatomical machinery to filter out food for a long, long time," said Jeremy Goldbogen, a comparative physiologist at Stanford University and author of the article, "It was not until the ocean provided these remedies that patches made Bulk feed filtration so efficient. " Whale whales could now swallow much larger quantities of prey, which allowed them to get bigger. But that was only part of the equation. Continue reading the main story Trilobites Uncover fascinating fragments of science. Feast under the summer Arctic sun, unless you are a worm JUL 3 Strange mammals that stunned Darwin They finally found a home JUL 3 This beautiful parasitic bird could soon appear in your yard JUN 29 Drumming cockroaches and the rhythms of love JUN 28 Solving the Scorching Mystery of the Sun's Erupting Plasma Jets JUN 23 More »Photo Baleen whales began to evolve to gigantic sizes about 4.5 million years ago. Credit SilverbackFilms / BBC "Plentiful food everywhere is not going to get giant whales," said Graham Slater, an evolutionary biologist at the University of Chicago and lead author of the study. Because the ecological cycles that feed krill and zooplankton bursts occur seasonally,
 Dr. Slater said that whales must migrate thousands of miles from the food patch to the food patch. The largest ancestors of whales that had larger fuel tanks had a better chance of surviving the long seasonal migrations to feed themselves, while the smaller whale bees became extinct. If the food patches were not far apart, Dr. Slater said, the whales would have grown to a certain body size that was comfortable for that environment, but they would not be the giants we see today. "A blue whale is able to move much more using much less energy than a small body whale," said Dr. Slater. "It was really advantageous if you were going to move long distances if you were big." Continue reading the main story Photo Blue whales are the largest animals that have ever existed. Ari S. Friedlaender, a behavioral ecologist at Oregon State University who did not participate in the study, said the research improved our understanding of how whales became giants.
 "What this does is that it allows us to be able to say that there are crucial processes in the ocean that allowed these animals to get this great," he said. Richard Norris, a paleobiologist at the Scripps Institution of Oceanography, called the study "a good job" and said it confirmed scientists' current understanding of changes in the oceans over time. "When we think about what the planet has been like in its long history, a whale 10 million years ago was a very different kind of critter than we have now," said Dr. Norris. "So in a sense we live in a special moment where we can enjoy the majesty of really big animals that are in the ocean