Whales, once land mammals, evolved to live in water through the process of natural selection. One important feature that allows whales to live in water is that their "nose" holes are located on their backs. Long ago, a random mutation produced at least one whale with a nose located higher than usual on the face. By easing the process of surfacing for air, this mutation helped that whale thrive in a sea environment. Consequently, the mutated whale had a higher chance of survival and reproduction, passing the trait on to subsequent generations. As time passed, subsequent mutations moved whale noses farther and farther back. After countless generations of evolution, whales are now born with noses on their backs.
Whale flippers help propel the large mammals through water but these appendages most likely evolved from front limbs. It's all part of their total evolution from land-based to sea-based mammals. Whale flippers are not all that different from human arms in basic structure and function [source: American Museum of Natural History]. Although these amazing sea creatures once walked and now dive and swim through the water, whale flippers also have a lot to teach us about aerodynamics. Moving through water and moving through air aren't that different, so scientists made models of humpback whale pectoral fins and tested them in a wind tunnel. Some models had the shape of the fin, but were smooth, and others included bumps like the tubercles real fins have. The models with tubercles outperformed the smooth ones in a number of ways: They had 32 percent less drag, 8 percent more lift and were less prone to stalling at steep wind angles. It seems nature knows how to ensure efficient movement.
In 2007, Northeastern Ohio Universities College of Medicine scientists published a report detailing their findings on a fossil called Indohyus, an ancient animal resembling a small deer. Some of its features resembled early whales. It's possible that several early mammals -- and by early, scientists mean about 35 million years ago -- used water to escape predators [source: BBC]. This may have been the beginning of water travel and evolution for the world's largest mammal.
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