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THE TITLE OF THE PROJECT: THE WHALE

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sami
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تاريخ التسجيل : 23/08/2010

THE TITLE OF THE PROJECT: THE WHALE

مُساهمة من طرف sami في الأربعاء سبتمبر 29, 2010 10:18 pm

THE TITLE OF THE PROJECT: THE WHALE





Whales are marine mammals. They are the largest animals ever to have lived.

Where whales live
Whales live in the Atlantic, the Indian and the Antarctic oceans.

What whales look like
Whales look like giant dolphins. The body is bursiform, resembling the streamlined form of a fish. The forelimbs, also called flippers, are paddle-shaped. The end of the tail holds the fluke, or tail fins, which provide propulsion by vertical movement. Although whales generally do not possess hind limbs, some whales (such as sperm whales and baleen whales) sometimes have rudimentary hind limbs; some even with feet and digits. Most species of whale bear a fin on their backs known as a dorsal fin. Beneath the skin lies a layer.



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Whales are divided into two suborders:

* The baleen whales are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water. They are the largest suborder of whale.
* The toothed whales have teeth and prey on fish, squid, or both. An outstanding ability of this group is to sense their surrounding environment through echo********.

Whales are special mammals
Like all mammals, whales breathe air into lungs, are warm-blooded, feed their young milk from mammary glands, and have some (although very little) hair.
Whales have a four-chambered heart. The neckvertebrae are fused in most whales, which provide stability during swimming at the expense of flexibility.
Whales also communicate with each other using lyrical sounds, called whale song. Being so large and powerful, these sounds are also extremely loud.
Females give birth to a single calf. Nursing time is long (more than one year in many species), which is associated with a strong bond between mother and young.

Whales are widely classed as predators, but their food ranges from microscopic plankton to very large fish.

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How long whales live
The Whale is the largest known mammal that has ever lived, and the largest living animal, at up to 35 m (105ft) long and 150 tons. Whales generally live for 40-90 years depending on their species and on rare occasions can be found to live over a century.

What may cause its extinction
Some species of large whales are endangered. This situation is due to:
1/ Whaling
For centuries whales have been hunted for meat and as a source of valuable raw materials. By the middle of the 20th century, large-scale industrial whaling had left many populations severely depleted, rendering certain species seriously endangered. Some species of large whales are endangered as a result of commercial whaling from the eleventh century to the twentieth. For centuries large whales have been hunted for oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales). By the middle of the 20th century, whaling left many populations severely depleted.
2/ Sonar interference
Environmentalists have long speculated that some cetaceans, including whales, are endangered by sonar used by advanced navies. In 2003 British and Spanish scientists suggested in Nature that sonar is

connected to whale beaching and to signs that the beached whales have experienced decompression sickness.
3/ Seismic testing
Conservationists are concerned that seismic testing used for oil and gas exploration may damage the hearing and echo******** capabilities of whales and suggest that such testing may also be responsible for beaching.
4/ Other human activities
Other human activities have been suggested to adversely impact whale populations, ranging from the unregulated use of fishing gear which catches anything that swims into it, to collisions with ships. Environmental toxins and the combination of toxins, particularly POPs (which concentrate up the food chain), have been shown to cause hearing loss by inhibiting the function of outer hair cells in the cochlea of the ear, and exposure to these toxins might affect whale echo********, leading to beaching.
5/ climate change and global warming
Whales are also threatened by climate change and global warming. As the Antarctic Ocean warms, krill populations, that are the main food source of some species of whales, reduce dramatically, being replaced by jelly like slaps .

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What we can do to save the whale
The International Whaling Commission introduced a six year moratorium on all commercial whaling in 1986, which has been extended to the present day. For various reasons some exceptions to this moratorium exist; current whaling nations are Norway, Iceland and Japan and the aboriginal communities of Siberia, Alaska and northern Canada. For details, see whaling.
Fishing gear and deployment modifications and eco-labeling have contributed to a reduction in the mortality of whales in recent years.
We, consumers, have to boycott goods made of whale parts.
We have also to exert pressure on governments so as they pass laws limiting whale fishing


    الوقت/التاريخ الآن هو الإثنين يناير 23, 2017 7:49 pm