Whale Essay Research Paper Whale weighs as

Whale Essay, Research Paper

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 Cetacea, along with dolphins, porpoises, and the narwhal. There are two basic types of living cetaceans: baleen, or whalebone, whales of the scientific suborder Mysticeti; 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 1900s. 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 glacialis) 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. australis. 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 bottlenosed 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 Artiodactyla, 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 zeuglodonts. Whether they are the ancestors of either modern suborder is a matter of conjecture. The largest archaeocete 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 Ale