Traditionally, scientists have thought that whales get so big because the buoyance of water frees them from the constraints of gravity. On land, for example, elephants can only get so big before they topple over. The buoyance issue may still be the case for whales, but new research provides another answer: They need to be big to keep themselves warm in cold water.
“It’s not that they could be big,” says William Gearty, an ecologist at Stanford, who lead the new study. “It’s that they must be big.” Published in the Proceedings of the National Academy of Sciences, the new study tells how scientists ran computer models trying to account for whales’ size. And body size was the most important trait; they need to be big to trap enough body heat to survive.
Over long periods of time, the scientists note, families of mammals tend to evolve into larger body sizes for many reasons – larger animals can fight off rivals for food, mating and other resources. And aquatic mammals do have the extra boost of buoyancy from their environment. Read more:
/https://news.nationalgeographic.com/2018/03/whales-size-animals-ocean-marine-mammals/
