Scientists have answered the main question – why are whales so big ?
No, I’m not going to tell you that baleen whales are very large. You already know that. Like that of a blue whale weighs 13-14 tons, the heaviest creature on the planet. But I’ll bet that you don’t know why these whales, which feed through a filter that big. Because even scientists don’t know. Anyway did not know until today. A group of scientists offered a fascinating theory in the Works of the Royal society B: reducing the fossil record and phylogenetic work (that is, determining the relationship of species to each other), they found that baleen whales probably have become a giant in just 3 million years ago — a trifle in the great scheme of evolution and this transformation was probably caused by climate change. This, of course, makes us think about what problems may face giant animals as the heating and acidification of the oceans of the Earth.
Baleen whales which swallow huge amounts of water and filter out tiny animals like krill, there are about 30 million years. During most of this time they were very modest stacked, staying long in 10 meters or so, that is three times less than the modern blue whale. In the end, to be a little convenient. At least easier to open the jaws when it is small.
At the beginning of the ice age about 3 million years ago the oceanic system began to change dramatically on a large scale. Ice sheets expanded to the North, and flows have sucked the nutrients out to sea. The increase of wind to upwelling (upwelling of deep waters to the surface) brought even more nutrients from the depths: when the wind blows off the upper layers of water, deep aspire to replace them. This has led to the flourishing of the plant phytoplankton, which in turn accelerated the reproduction of zooplankton — krill — who eats first. The food of the whales began to gather in certain places at certain times of the year.
The large size would be an advantage for whales in the midst of this climate of transformation due to several factors (this trait evolved independently in different pedigrees of baleen whales, confirming the advantage of the development). First, large whales has changed with the food chain, growing to such proportions that placed itself out of reach of predators. Big mouth also more efficiently captured zooplankton. If you can accumulate more fat, you can continue to migrate, in contrast to the small whales that were hanging out in the surrounding waters with low concentrations of plankton.
“We believe that it is an environmental explanation for the change in the size of the body,” says paleobiology and study co-author Nick Penson from the Smithsonian University. “Explains not only the origin of the very large, but also the disappearance of very small baleen whales, which are now represented in this pedigree, only a whale-pygmy.” Smaller whales simply could not compete in the new world order, but why couldn whale-pygmy is a mystery.
But couldn’t the whales to become big just because they could? After all, swim in the water is not that great with body on the ground. “When you study the data, it is excluded,” says Penson. “When the whale hits the water and becomes very large — that’s not so.” In the end, baleen whales lived in water millions of years before becoming a giant.
But what the study shows for sure is the exceptionality of this moment in the natural history of the Earth. Just imagine that you need to maintain not only blue whales, but other baleen whales, like gray. They eat while traveling thousands and thousands of nautical miles. “In history there was still time, when such large predators would find as much fertile biomass in the oceans,” says vertebrate paleontologist Erich Fitzgerald, who did not participate in the study. “Unique in the history just yet. Can be traced back to the end of the era of the dinosaurs, 66 million years ago, and only the last 3 million years will be truly unique.”
People can to ruin it. Small changes in the temperature of the oceans can have a cascading effect on the ecosystem. If currents change or appallingly cold water will stop the output of nutrients to the surface, phytoplankton don’t bloom and the zooplankton will eat. If there is no zooplankton, baleen whales have nothing to eat. If the bloom will move into other areas of the sea and the whales will not be able to find, their advantage in size suddenly becomes a burden.
Climate change has created giants, and although it is too early to say how it will affect them in the coming decades, the giants are certainly in a dangerous situation. Large creatures are at the cutting edge of evolution, by definition. Yes, science has found that large whales were due to climate change. Now we have to ensure that further climate change won’t hurt them.
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