Whales are enormous in size compared to all other animals. The blue whale is one of the largest animals that has ever lived, reaching a length of over 24 m (80 ft) and a weight of 150 metric tons. Its heart is as big as a Volkswagen Beetle, and its body is almost as large and about as heavy as that of the largest known dinosaur.
Whales have a streamlined, rounded body tapering in the rear to a pair of broad horizontal tail flukes that provide the main propulsive thrust for swimming. They have paddle-shaped flippers that help stabilize and steer the whale while swimming. The bones of the flippers resemble the jointed limbs and digits of land mammals. Many whales have a dorsal fin located at or behind the center of the back.
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