Whales range in size from the blue whale, the largest animal known to have ever existed at 35 m (115 ft) and 150 tonnes (150 LT; 170 ST), to various pygmy species, such as the pygmy sperm whale at 3.5 m (11 ft).
Whales co
llectively inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3-13%. For centuries, whales have been hunted for meat and as a source of raw materials. By the middle of the 20th century, however, industrial whaling had left many species seriously endangered, leading to the end of whaling in all but a few countries.Taxonomy
Cetaceans are divided into two suborders:
* The largest suborder, Mysticeti (baleen whales) are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which it uses to filter plankton from the wa
ter.* Odontoceti (toothed whales) bear sharp teeth for hunting. Odontoceti also include dolphins and porpoises.
Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippopotamuses. Whales are the hippopotamus's closest living relatives.
Sperm Whales:
It seemed only natural for deep-diving sperm whales to be immune from decompression illness, or the bends—the painful, sometimes fatal condition that human divers suffer when they surface too rapidly. But the whales may be as susceptible as land mammals, according to a new study by WHOI biologists.Michael Moore and Greg Early examined bones from 16 sperm whale skeletons archived in several museums and detected telltale patches of dead bone (or osteonecrosis), which w ere most likely caused by nitrogen bubbles that form when divers decompress too rapidly.
Only the bones of whale calves did not show signs of osteonecrosis, the scientists found, and the bone damage became more severe in larger (older) whales—an indication t
hat osteonecrosis caused by decompression illness is a chronic, progressive disease among sperm whales.When air-breathing mammals dive to high-pressure depths, the nitrogen in their bodies becomes supersaturated in their tissues. If they rise too quickly, the pressure is released too suddenly. The nitrogen reverts to gas, forming bubbles, or emboli, which can obstruct blood flow and lead to bone damage.
Moore and Early launched their study in 2002 after a necropsy of a sperm whale found dead on a Nantucket Beach revealed evidence of osteonecrosis. Intrigued, they decided to examine as many sperm whale skeletons as possible.
Their inventory included whales from the Pacific and Atlantic, and whales that died as long as 111 years ago—so the newly found phenomenon is neither localized nor recent.
Sperm whale dives typically last about an hour, but can be up to two hours, and they g o to depths of 1,000 to 2,000 meters in search of their preferred prey: squid. The scientists theorize that the whales normally manage their surfacing behavior to decompression problems. But if a noxious sound—from a sonar, for instance, or seismic airguns used in oil exploration—disrupts their usual behavior and provokes fast surfacing, the whales risk acute proble ms from nitrogen emboli.
Moore and Early reported their findings in the journal Science. Their study was supported in part by the NOAA Fisheries John H. Prescott Marine Mammal Rescue Assistance Program.
The skeleton from the original specimen is now on display at the New Bedford Whaling Museum.
Source:http://www.whoi.edu/oceanus/viewArticle.do?id=4720
Beluga Whales:
"White Whale" redirects here. For other uses, see White Whale (disambiguation).
Beluga
Size comparison against an average human
Conservation status
Near Threatened
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Monodontidae
Genus: Delphinapterus
Species: D. leucas
Binomial name
Delphinapterus leucas
(Pallas, 1776)
Beluga range
The beluga or white whale (Delphinapterus leucas) is an Arctic and sub-Arctic species of cetacean. It is one of two members of the family Monodontidae, along with the narwhal. This marine mammal is commonly referred to simply as the beluga or sea canary due to its high-pitched twitter. It is up to 5 meters (16 ft) in length and an unmistakable all-white color with a distinctive protuberance on the head. From a conservation perspective, the beluga is considered "near threatened" by the International Union for Conservation of Nature; however the subpopulation from the Cook Inlet in Alaska is considered critically endangered and is under the protection of the United States' Endangered Species Act.
Taxonomy:
In 1776 Peter Simon Pallas first described the beluga. It is a member of the Monodont idae family, which is in turn part of the toothed whale suborder. The Irrawaddy dolphin was once placed in the same family; however, recent genetic evidence suggests otherwise. The narw hal is only other species within the Monodontidae family besides the beluga.The Red List of Threatened Species gives both beluga and white whale as common names, though the former is now more popular. The English name comes from the Russian белуга (beluga) or белуха (belukha), which derives from the word белый (belyy), meaning "white". It is sometimes referred to by scientists as the belukha whale in or der to avoid confusion with the beluga sturgeon.
Source:http://en.wikipedia.org/wiki/Beluga_(whale
Blue whale:
BLUE WHALE(Balaenoptera musculus)
The blue whale is one of the rorquals, a family that includes the humpback whale, fin whale, Bryde's whale, sei whale, and minke whale.
The blue whale is the largest mammal, to inhabit the earth. Its body is lengthy, so mewhat slender, and streamlined. The Blue Whale's head makes up about one-fourth of its total body length. Its upper part of the head is very broad and low with a single ridge in front of the blowholes to the tip of its nose. When the whale blows, its flume rises up to about 20 feet high.
This giant animal, the Blue Whale is placid and shy and has a few barnacles that attach themselves to the fluke, the tips of the flippers and dorsal fin.
Unlike humans, whales breathe voluntarily. That means they choose when to take a breath. This is important because whales can't breath under water. They surface every few minutes to blow out a mixture of water and air and take in a breath of fresh air. Whales have belly buttons, too just like you and me. Like all mammals, they give birth and nurse live young.
COLOR The Blue Whale is blue-gray in color with a lighter and darker gray splotching. The undersides of its flippers have an ivory color, and the under side of the flipper is dark. Because of the cold waters of the Antarctic, North Pacific and North Atlantic its belly has a yellowish green caste. Early whalers called the Blue Whale, "Sulfur Bottom."
The Blue Whale's dorsal fin is small and curved and the location of the fin is about 3/4ths of the way back on the body. The dorsal fin measures about 12 inches high. Its flippers are narrow and about 9 1/2 feet long. The length of the adult blue whale is 80 feet long
. The male Blue Whale weighs about 110 tons while the females being larger weigh up to 150 tons.They feed at depths of less than 330 feet (but can dive as deep as 1,640 feet). Dives last from 10 to 20 minutes. The Blue Whale feeds almost exclusively on krill. During the summer the Blue Whale consumes about 4 tons of krill daily or about 40 million krill a day.
As a baleen whale, the Blue Whale has hundreds of fringed plates on each side of the upper jaw. These plates consist of keratin that separate into loose little hairs inside the mouth near the tongue.
Source:http://www.suite101.com/article.cfm/arctic_wildlife/106362
