[pic]The largest creature ever known to have existed on Earth is the present-day blue whale. The largest dinosaur attained a length of about 22 m and weighed about 36 tons. Today’s blue whale is even larger than its ancestors, and may reach a total length of 33 m and a weight of 145 tons. This giant animal is placid and shy. On the ocean surface, its normal cruising speed is about 12 knots, but it is capable of attaining 20 knots in short bursts. The maximum reported depth reached by the species is 194 fathoms. It is capable of remaining submerged beneath the surface for 50 minutes, although 10 to 15 minutes is more typical. The life span of a blue whale is about 30 years. The calves measure 7 m at birth and weigh about 2 tons. By the time they are a year old, the youngsters measure 18 m. Blue whales comprised about 90 percent of the whaling industry’s total catch during the early part of this century. In 1931, more than 30,000 of these majestic creatures were killed. Since then, the blue whale population has declined and was on the brink of extinction. Today about 11,000 are suspected to exist. The blue whale is the largest animal on Earth, some as long as 100 feet and weighing up to 300,000 pounds. But size does not protect this swift, powerful mammal from the threat of extinction that has loomed over them since the 19th century, when their population was cut down to 1 percent of its original size. There is not one specific factor in their endangered status, but rather, there are several reasons why this gentle giant is on the verge of extinction. Other People Are Reading
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• [pic]What Are the Causes of Endangered Whales?
o In the 1900s, whales meant huge profits to deep sea fishermen. From one whale, 120 barrels of oil could be produced. Fishermen improved the numbers of catches by perfecting whale catching techniques and they used harpoons for spearing the giant beast. Their population was cut down to 1 percent of its original size. The thick layer of blubber on a blue whale is to keep it warm, but humans have found multiple other uses for the tissue. It is used for the production of fuel, oil, soap and candles. Their baleen was used to make brushes and corsets rather than filter krill for the animal's food. Hunting has been the biggest downfall of the population of this species due to the financial gains humans can make from their bodies. It is no longer considered a problem due to the ongoing efforts of worldwide conservation efforts. Noise Pollution
o Rather than sight, blue whales use echolocation to determine their location and direction. This ultrasonic noise helps guide them along and avoid objects and swimming in shallow waters. When the navy tests equipment underwater, the sound and vibration can create interference that confuses the whale, sometimes causing them to beach themselves or get hit by ships. Being struck by ships is now the biggest threat to the blue whale population. In 2007, three blue whale fatalities were confirmed to be caused by collisions with ships. The problem has gotten so serious that the National Oceanic and Atmospheric Association (NOAA) is attempting to lower boat speed limits and consolidate shipping routes to reduce a ship's chance of encountering a whale. o Sponsored Links
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Environmental Pollution and Degradation
o Chemicals such as pesticides and oil are a serious problem for blue whales. These toxins collect in the fat stores of adult whales and contaminate a nursing cow's milk. Environmental pollution leading to an increase of ocean water temperature has several negative effects on the well-being of blue whales. The warmer water harbors the growth of viruses, parasites, and toxic algae, and it also...
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