A Northern Right Whale.

The term whale can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. The last definition is the one followed here. Whales are those cetaceans which are neither dolphins (i.e. members of the families Delphinidae or Platanistoidea) nor porpoises. This can lead to some confusion because Orcas ("Killer Whales") and Pilot whales have "whale" in their name, but they are dolphins for the purpose of classification.

Origins and taxonomy

A Fin Whale.

See also: Evolution of cetaceans

All cetaceans, including whales, dolphins and porpoises, are descendants of land-living mammals of the Artiodactyl order (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippos. In fact, whales are the closest living relatives of hippos; they evolved from a common ancestor at around 54 million years ago.^[1] Whales entered the water roughly 50 million years ago.^[2]

Cetaceans 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 species 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 echolocation.

A complete up-to-date taxonomical listing of all cetacean species, including all whales, is maintained at the Cetacea article.

Anatomy

Physical characteristics of a baleen whale.

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.

The body is fusiform, 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 of fat, the blubber. It serves as an energy reservoir and also as insulation. Whales have a four-chambered heart. The neck vertebrae are fused in most whales, which provides stability during swimming at the expense of flexibility. They have a pelvis bone, which is a vestigial structure.

Whales breathe through blowholes, located on the top of the head so the animal can remain submerged. Baleen whales have two; toothed whales have one. The shapes of whales' spouts when exhaling after a dive, when seen from the right angle, differ between species. Whales have a unique respiratory system that lets them stay underwater for long periods of time without taking in oxygen. Some whales, such as the Sperm Whale, can stay underwater for up to two hours holding a single breath. The Blue 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 40-200 years, depending on their species, but it is rare to find one that lives over a century. Recently a fragment of a lance used by commercial whalers in the 19th century has been found in a bowhead whale caught off Alaska. The fragment showed the whale is between 115 and 130 years old. ^[3] "No other finding has been this precise," said John Bockstoce, an adjunct curator of the New Bedford Whaling Museum.^[4]

Whale flukes often can be used as identifying markings, as is the case for humpback whales. This is the method by which the publicized errant Humphrey the whale was identified in three separate sightings.

Anatomy of the ear

See also: Evolution of cetaceans

While there are direct similarities between the ears of whales and humans, whales’ ears have specific adaptations to their underwater environment. In humans, the middle ear works as an impedance matcher between the outside air’s low-impedance and the cochlear fluid’s high-impedance. In aquatic mammals such as whales, however, there is no great difference between the outer and inner environments. Instead of sound passing through outer ear to middle ear, whales receive sound through their lower jaw, where it passes through a low-impedance, fat-filled cavity.^[5]

Behaviour

A Humpback Whale breaching.

A kenning in Beowulf refers to the sea as the "whale-road".

Procopius mentions a whale, nicknamed Porphyrio by the Byzantines, who depleted fisheries in the Sea of Marmara.

The King James Version of the Bible mentions whales four times: "And God created great whales" (Genesis 1:21); "Am I a sea, or a whale, that thou settest a watch over me? (Job 7:12); "Thou art like a young lion of the nations, and thou art as a whale in the seas (Ezekiel 32:2); and "For as Jonas [sic] was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth" (Matthew 12:40).

• Nevertheless, the passages in question do not unambiguously refer to whales; modern translations tend to use other terms; for example the New International Version uses "creatures of the sea"; "monster of the deep"; "monster"; and "huge fish" respectively.
• The story of Jonah being swallowed by a whale is mentioned in the Qur'an as well.

A whaling voyage is the plot of Herman Melville's novel Moby-Dick. In the book, Melville classed whales as "a spouting fish with a horizontal tail", this despite science suggesting otherwise the previous century. (His narrator acknowledged "the grounds upon which Linnaeus would fain have banished the whales from the waters" but writes that when he presented them to "my friends Simeon Macey and Charley Coffin, of Nantucket ... they united in the opinion that the reasons set forth were altogether insufficient. Charley profanely hinted they were humbug" (Chapter 32).) Melville's book is a classic of American literature: part adventure novel, part metaphysical allegory, and part natural history; it is essentially a summary of 19th century knowledge about the biology, ecology and cultural significance of the whale.

Some cultures associate some level of divinity with the whale, such as in some places in Ghana and the Vietnamese, who occasionally hold funerals for beached whales, a throwback to Vietnam's ancient sea-based culture.

Festivals celebrating whales have sprung in both Sitka and Kodiak Alaska. They feature speakers on marine biology and celebrate the creatures with art, music, whale watching cruises, and symposia.

In the British series Hitchhiker's Guide to the Galaxy a whale, alongside a bowl of petunias, is created by the use of the Infinite Improbability Drive

See also

Cetaceans Portal

• Cetacea
• List of whale species
• Category:Cetaceans

References

1. ^ Dawkins, Richard (2004). The Ancestor's Tale, A Pilgrimage to the Dawn of Life. Boston: Houghton Mifflin Company. . 
2. ^ How whales learned to swim. BBC News (2002-05-08). Retrieved on 2006-08-20.
3. ^ Hunting lance from 1800s found in whale. Retrieved on 2007-06-14.
4. ^ 19th century weapon found in whale. Retrieved on 2007-06-14.
5. ^ Anatomy of a Whale's Ears. Retrieved on 2006-09-14.
6. ^ Table of sound decibel levels. Retrieved on 2006-09-14.
7. ^ Sonar may cause Whale deaths. BBC News (2003-10-08). Retrieved on 2006-09-14.
8. ^ Seismic testing and the impacts of high intensity sound on whales. Retrieved on 2006-09-14.

General references

• Carwardine, M. (2000). Whales, Dolphins and Porpoises. Dorling Kindersley. . 

External links

• Whale Evolution
• images and movies of Whales and Dolphins, text in French
• Greenpeace work defending whales
• Save the Whales, founded in 1977
• AquaNetwork Marine Mammal Project
• Oldest whale fossil confirms amphibious origins
• The Oceania Project - Caring for whales and dolphins
• Research on dolphins and whales from Science Daily
• Whale and Dolphin Conservation Society - latest news and information on whales and dolphins

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