Written by: Eshita Lal Shrestha - 2027024, Grade V
Posted on: 14 December, 2020
Blue whales are the largest animal ever known on earth. These marine mammals rule the ocean. Up to 100 feet long and more than two hundred tons their tongues alone can weigh as much as an elephant. Their heart is as big as an automobile. Blue whales reach these mind-boggling dimensions on a diet composed nearly exclusively of tiny shrimplike animals called krill. During certain times of the year, a single adult blue whale consumes about 4 tons of krill a day. 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. Then the whale's massive tongue forces the water out through the thin, overlapping baleen plates. Thousands of krill are left behind and then swallowed. Blue whales look true blue underwater, but on the surface, their coloring is more like 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, triangular flukes. Blue whales live in the world’s oceans, except the Antarctic. These mammals occasionally swim in small groups but usually alone or in pairs. They often spend summer feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives. These graceful swimmers can accelerate more than 20 miles an hour when they speed up. Blue whales are among the loudest animals on the planet as well. They emit a series of pulses, groans, and moans, and it’s thought that, in good conditions, blue whales can hear each other up to 1000 miles away. Scientists think they use these vocalizations not only to communicate but, along with their excellent hearing, to sonar-navigate the lightless ocean depths. Calves enter the world already ranking among the planet's largest creatures. After about a year inside its mother's womb, a baby blue whale emerges weighing up to 3 tons and stretching to 25 feet. It gorges on nothing but mother's milk and gains about 200 pounds every day in its first year. Source: Encyclopedia on mammals
