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Blue Whales

    Blue whales are the largest animals ever known to have lived on Earth. These magnificent marine mammals rule the oceans at up to 30 meters  long and up wards of  200 tons. Their  tongues alone can weigh as much as an elephant. Their hearts, as much as an automobile.

    Blue whales are baleen whales, which means they have fringed plates of fingernail-like material, called baleen, attached to their upper jaws. The giant animals feed by first gulping an enormous mouthful of water, expanding the pleated skin on their throat and belly to take it in. During the certain times of the year, a single adult blue whale consumes about 4 tons of krill a day.

    Blue whales look true blue underwater, but on the surface their coloring is more a mottled blue-gray. Their underbellies take on a yellowish hue from the millions of microorganisms that take up residence in their skin. The blue whale  has a broad, flat head and a long, tapered body that ends in wide, tringular flukes.

    Blue whales lives in all the wolrd’s ocean occasionally swimming in small groups but usually alone in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives.

    Blue whales are among Earth’s longest-lived animals. The oldest blue whale found using this method was determined to be around 110 years old. Average lifespan is estimated at around 80 to 90 years.

    Between 10.000 and 25.000 blue whales are believed  to still swim the world’s oceans. Aggressive hunting in the 1900s by whalers seeking whale oil drove them to the brink of extinction. Between 1900 and the mid-1960s, some 360.000 blue whales were slaughtered. They finally came under protection with the 1966 International Whaling Commission, but they’ve managed only a minor recovery since then.

    Blue whales have few predators but are known to fall victim to attacks by sharks and killer whales, and many are injured or die each year from impacts with large ships. Blue whales are currently classified as endangered on the World Conservation Union (IUCN) Red List.

Write the supporting sentences of each main idea in the given box. (diet)