Whales have evolved to swim easily through water using vertical strokes of their tails, while their flippers aid in changing direction, balancing, and stopping, according to the National Marine Life Center. Their streamlined bodies are designed for speed in the water.
Many cetaceans, which include whales, dolphins and porpoises, have dorsal fins that act as rudders, or stabilizers. They have strong muscles that run along their spines and the sides of their bodies to move their flukes up and down, rather than side to side like fish. Their flukes, or tails, are powerfully muscled to help them swim and dive rapidly to catch prey and evade predators. A sperm whale can dive to 7000 feet to hunt squid, a favorite food.
To minimize drag while in the water, their bodies have lost some of the physical features their land-dwelling ancestors had, such as hind legs, ears and body hair. Modern cetaceans have flattened ear holes, streamlined flippers, wide flat tails, and blowholes to make breathing easier while they move through the water,
Contrary to popular belief, even the largest whales are very maneuverable for their size. Blue whales, the world’s largest mammal, can reach 100 feet or the height of a 10 story building. Yet, according to Discovery, a blue whale can swiftly turn 360 degrees and accelerate up to 11 kph (6.8 mph) while in pursuit of krill, its primary source of food.