Blue Whale
05.40
Source: http://www.howstuffworks.com
Blue whales are the largest animal water that has ever lived. Blue whales look blue underwater but actually are speckled blue-gray and white. Tiny yellow organisms sometimes grow on their undersides, making their bellies look yellow. These tiny organisms do not affect the whale at all. Blue whales have good eyesight. Blue whales swim at a top speed of about 30 mph (48 km/h).
A blue whale’s heart is the size of a small car. Its tongue weighs as much as an elephant. A toddler could easily fit into one of its blowholes. A single blue whale is heavier than a group of 1,600 average-sized people. A blue whale can reach 100 feet (30 meters) in length and may tip the scales at 300,000 pounds (136,000 kilograms). The female blue whales are larger than males.
Blue whales inhabit some of the coldest waters and some of the warmest waters on the planet. Yet, they maintain a constant body temperature of about 98 degrees Fahrenheit (36.6 degrees Celsius), nearly the same as our body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius). Amazingly, blue whales are so well adapted for cold temperatures that it is easy for them to keep warm in cold waters. The shape and large size of a blue whale’s body help it to retain heat.
Blue whales live in all the oceans. Their summer feeding areas are in or near the waters of the cold Polar Regions. In winter, blue whales migrate to breed and give birth in the comforting warmth of the tropics. Sometimes migrating whales travel thousands of miles between their winter and summer habitats.
Blue whales actually have a harder time getting rid of excess heat. So, unlike other whales, they don’t need as thick a layer of blubber. A blue whale’s blubber is only 6 inches (15 centimeters) thick, whereas some other whales are covered in a 20-inch (51-centimeter) layer. A blue whale may get rid of excess heat by sending more blood than normal to its skin surface, which cools the whale’s blood.
Blue whales that spend the summer months in cold polar waters eat a whole lot of one thing—krill. Krill resemble shrimp But smaller than the shrimp people eat. Krill make good whale food because of their abundance and high nutritional value. Pound for pound, krill contain as much protein as red meat, and they contain all the energy, trace minerals, and vitamins that blue whales require. It does, however, take a lot of krill to fill a hungry whale. During the summer feeding season, a blue whale may devour over 10,000 pounds (4,536 kilograms) of krill a day.
When blue whales feed, they take huge gulps of water. For this reason, they are called gulpers. Blue whales have pleats on their throat that expand just like an accordion. By gulping, they transform their throat into a giant pouch. By pressing their tongue against their baleen, the whales squeeze out the water. Then they eat the krill that remain trapped against the baleen.
Newborn whales are the most vulnerable because they are small and swim slowly. Mother whales swim beside their young, shielding them from predators. If a group of killer whales targets a young whale, however, it is a challenge to protect it. Lacking teeth, claws, or tusks, blue whales have only their size—and powerful tail—to ward off attack. Killer whales will rip small chunks of flesh from a young or sick whale until it finally dies.
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