Southern Right Whale In A Separate Species example essay topic

Whale weighs as much as 20 elephants but lives beneath the sea. The blue whale is Earth's largest animal. Larger than the largest of ancient dinosaurs, blue whales can grow to be more than 100 feet (30 meters) long and weigh nearly 150 tons. Not all whales are so large. The much smaller pilot whale grows to about 28 feet (8.5 meters) in length. And dolphins, which belong to the whale family, range only from 3 to 13 feet (1 to 4 meters).

Although whales spend their lives in the sea, they are, like humans, warm-blooded mammals. After a baby whale is born, it nurses on its mother's milk, just like the young of land mammals. Whales are members of the order Cetacean, along with dolphins, porpoises, and the narwhal. There are two basic types of living cetaceans: baleen, or whalebone, whales of the scientific suborder Mystic eti; and toothed whales of the suborder Odontoceti. General Characteristics Whales live in all of the open seas of the world, though some occasionally enter coastal waters.

Some species, such as the white whale, or beluga, may travel upstream in large rivers. Some species migrate with the seasons; others remain year-round in the same habitats, where they find their preferred food. The present-day distribution and abundance of some species has been greatly influenced by the commercial whaling industry. Whalers eliminated or greatly reduced the numbers of some species of baleen whales in certain oceanic regions where whales once frolicked in abundance.

This is particularly true in parts of the Arctic Ocean and the eastern North Atlantic Ocean, where the blue whale was almost completely exterminated in the early 1900's. Some species of whales, however, are numerous today in the Arctic and Antarctic regions. The skin of whales is usually black, gray, black and white, or all white. Some, such as the blue whale, have skin that is bluish-gray. The surface of the skin is smooth, but like other mammals, whales have hair.

Hair first appears while the fetal whale is still developing inside its mother's womb. In adult whales, hair is confined primarily to a few bristles in the head region and is largely absent over most of the body. Whales that live in polar regions are insulated from the extreme cold by a layer of blubber, or fat, enveloping their bodies. Baleen Whales The baleen whales include the family of right whales, Balaenidae, so named because whalers considered them 'just right' easy to kill and full of oil and whalebone.

Among these are the black right whale (Eubalaena glacial is) of both northern and southern seas. Scientists believe that those in the western North Atlantic may be gradually increasing in numbers. However, populations in the eastern North Atlantic and in both the eastern and western North Pacific show no signs of recovery, and only a few remain in each area. An estimated 1,500 to 3,000 occur in the southern oceans, with little evidence of a significant increase in population sizes in most areas. Some scientists place the southern right whale in a separate species: E. austral is.

Black right whales reach lengths of 70 feet (21 meters) and are black on the upper body. The underside is sometimes paler in color. The baleen plates in the mouth may be more than 8 feet (2.4 meters) long. Toothed Whales The toothed whales include more than 65 species in six different families. Among these are the true dolphins (family Delphinidae), which includes the pilot whales (genus Globicephala) and the killer whale (Orcinus orca), largest of the oceanic dolphins.

Killer whales prefer coastal waters to the open ocean. They hunt in schools and, though relatively small at 30 feet (9 meters), will attack other whales two or three times their size. Two other families include the true porpoises (Phocoenidae), which are marine species, and the river dolphins (Platanistidae), consisting of six species of primarily freshwater or estuarine forms. The remaining three families are the sperm whales (Physeteridae), the beaked whales and bottle nosed whales (Ziphiidae), and the white whales and narwhal (Monodontidae). Evolution Recent studies based on genetic sequences have confirmed that all cetaceans were derived from a single ancestral stock and are closely related to the hoofed mammals in the order Artiodactyl a, made up of the even-toed mammals, such as cattle, deer, and camels. Nevertheless, the evolutionary origin of whales remains controversial among zoologists.

The oldest fossils clearly recognizable as primitive whales were discovered in the Eocene epoch excavation layer of sites in Nigeria and Egypt. These early forms are placed in an extinct suborder (Archaeoceti) known as. Whether they are the ancestors of either modern suborder is a matter of conjecture. The largest was Basiolsaurus, a whale from the late Eocene epoch that reached a length of almost 70 feet (20 meters). History of Whaling Archaeological evidence suggests that primitive whaling, by Inuit and others in the North Atlantic and North Pacific, was practiced by 3000 BC and has continued in remote cultures to the present. The primitive quarry were small, easily beached whales or larger specimens that came close to shore during seasonal migrations from polar feeding grounds to breed in sheltered bays.

The Japanese used nets, and the Aleuts used poisoned spears. The Inuit successfully hunted large whales from skin boats, employing toggle-headed harpoons attached by hide ropes to inflated sealskin boats. In Europe, the Nordic people hunted small whales, and Icelandic laws dealt with whaling in the 13th century. Conclusion In 1946 the International Whaling Commission (IWC) was established to set up the guidelines followed by whaling nations today. The sizes, kinds, locations, and seasons of catches are controlled.

However, strong international politics came into play, and some nations steadfastly voted against, or even ignored, restrictions that were not economically advantageous. The limitations were passed almost too late for the blue whale, which had already declined to dangerously low numbers in all oceans. The once large populations of blue whales in the eastern North Atlantic were almost brought to extinction. Today, fewer than 500, and possibly as few as 100, are found there. In 1971 the United States declared all commercially exploited whales endangered species and made it illegal to import any whale products. The United States lists the blue, bowhead, finback, gray, humpback, right, sei, and sperm whales as endangered species.

Therefore, we should take goof care of whale.

Bibliography

Cousteau, Jacques, and Paccalet, Yves. Whales (W.H. Allen, 1998).
Tinker, S.W. Whales of the World (Bess Press, 1997).
Day, David. The Whale War (Sierra Club Books, 1997).