Origins of the Blue Whale

     Marine mammals in the cetacean family include whales, dolphins, and porpoises. Although whales spend all their time in the oceans, they are mammals just like us. This means that they are warm blooded, give birth to live young, nurse their young, have traces of hair or fur, and must come to the surface to breathe air through their lungs.

     Millions of years ago, the ancestors of whales lived on land. Scientists believe these land ancestors looked like small dogs, were more closely related to hippos, and went into the ocean about 60 million years ago. Over time, these ancestors changed or adapted, to survive in their new ocean environment. Their front legs turned into paddle-shaped flippers, they lost their back legs, their tails grew larger and widened to form flukes, and they developed a thick layer of fat, called blubber, to keep warm in the ocean. Also, their skulls elongated and the nostrils shifted to the back of their heads to aid in breathing at the ocean's surface. They developed a series of adaptations related to diving, which include the ability to store more oxygen in their blood and muscles, and more blood volume relative to their body size than land mammals.

     Cetaceans are separated into two groups: toothed and baleen whales. The baleen whales are a group that includes 11 species ranging from the smallest, the pygmy right whale at 21 feet (6.4 m), to the largest baleen whale, the Blue whale, which by now you've surely read is the largest animal that ever lived on planet earth.

     Baleen whales have two blowholes instead of one, and in the place of teeth in their mouths, they have hundreds of rows of baleen plates, which are made of keratin, a substance in our hair and fingernails. They act as filters for catching food. Most baleen whales feed by taking a large mouthful of food and water, and then push the water out through their baleen plates with their tongues. The food gets trapped behind the baleen. Most baleen whales eat krill (shrimp-like animals) or small fish. Right and bowhead whales are baleen whales that feed in a slightly different way called skimming. Water and food flows through a gap in the front of their baleen plates, the food gets trapped inside the baleen, and the water flows out through gaps on the sides of their mouths.

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