Whales are members of the order Cetacea, which also includes dolphins and porpoises. They are the largest mammals, the largest vertebrates, and the largest known animals in the world.
Unlike fish, which breathe air using gills, whales breathe air through blowholes that lead into their lungs.
Whales are those cetaceans that are neither dolphins (i.e. members of the families Delphinidae or Platanistoidea) nor porpoises (several families). 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. Sometimes the terminology whale is used to refer to all cetaceans, including dolphins and porpoises, but generally it is used for particular families within Cetacea.
Whales, whose representatives include the largest animals that have ever appeared on Earth, are celebrated in art, music, and literature. Yet, they have also been subject to severe overhunting, habitat destruction, and competition for resources. Many species of whales have ended up on the list of endangered species, and humpbacked whales alone declined by an estimated 95 percent in just the twentieth century. As stewards of creation, humanity has a responsibility to better understand and conserve these remarkable animals, which combine grace, power, intelligence, and beauty.
Origins and taxonomy
Whales, along with most dolphins and porpoises, are descendants of land-living mammals, most likely of the Artiodactyl order. They are considered to have entered the water roughly 50 million years ago.
Cetaceans are divided into two suborders:
- The baleen whales (Mysticeti) are characterized by the baleen, a sieve-like structure in the upper jaw made of the tough, structural protein keratin. The baleen is used to filter plankton from the water. Baleen whales are the largest whales. They are characterized by two blowholes. The families of baleen whales include the Balaenopteridae (humpback whales, fin whales, Sei Whale, and others), the Balaenidae (right and bowhead whales), the Eschrichtiidae (gray whale), and the Neobalaenidae (pygmy right whales), among others. The Balaenopteridae family (rorquals) also includes the Blue Whale, the world's largest animal, and perhaps the largest animal ever to roam the earth. It reaches 30 meters (93 feet) long and can weigh up to 180 tons.
- The toothed whales (Odontoceti) have teeth and prey on fish, squid, or both. This suborder includes dolphins and porpoises as well as whales. An outstanding ability of this group is to sense their surrounding environment through echolocation. Toothed whales have only one blowhole. In addition to numerous species of dolphins and porpoises, this suborder includes the Beluga whale and the sperm whale, which may be the largest toothed animal to ever inhabit Earth. Families of toothed whales include the Monodontidae (belugas, narwhals), Kogiidae (Pygmy and dwarf sperm whales), Physteridae (sperm whale), and Ziphidae (beaked whales).
Like all mammals, whales breathe air into lungs, are warm-blooded, breast-feed their young, and have hair (although very little).
The whales' ancestors lived on land, and their adaptations to a fully aquatic life are quite striking. 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.
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.
Whales also have very sensitive hearing said to be 20 times as sensitive as that of a human.
Whales are broadly classed as predators, but their food ranges from microscopic plankton to very large fish. Males are called bulls; females, cows. The young are called calves.
Because of their environment (and unlike many animals), whales are conscious breathers: they decide when to breathe. All mammals sleep, including whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious in order to breathe. It is thought that only one hemisphere of their brains sleeps at a time, so that whales are never completely asleep, but still get the rest they need. Whales are thought to sleep around 8 hours a day.
Whales also communicate with each other using beautiful lyrical sounds. Being so large and powerful, the sounds made by these animals are also extremely loud and can be heard for many miles. They have been known to generate about 20,000 acoustic watts of sound at 163 decibels, just below that of internal sound pressure of a large airplane turbine motor (Hamby 2004).
Some whales live solitary or in small groups. Others live in family groups in a lifetime relationship, or live in social groups. Social groups of humpback whales tend to be short-lived, while toothed whales appear to have longer lasting social bonds among groups (Whale Trust 2006).
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. In most whales, reproductive maturity occurs at seven to ten years. This strategy of reproduction spawns few offspring, but provides each with a high rate of survival.
The genital organs are retracted into cavities of the body during swimming, so as to be streamlined and reduce drag. Most whales do not maintain fixed partnerships during mating; in many species the females have several mates each season. At birth, the newborn is delivered tail-first, so the risk of drowning is minimized. Whale mothers nurse the young by actively squirting the fatty milk into their mouths, a milk that according to German naturalist Ernst Dieffenbach bears great similarities to cow's milk. Biologists compare the consistency of whale milk to cottage cheese; it must be thick, or else it will dissipate into the surrounding water.
Some species of cetaceans have been described as being very playful, spending three times as much time playing as they do searching for food. Whales can go up to eight months without food. It is said they do not work to eat, they play to eat.
Whale behaviors include singing, spy hop, tail extension, flippering, tail lob or slap, tail throw, breach, head lunge, and bubble tail (Whale Trust 2006).
Many people believe that cetaceans in general, and whales in particular, are highly intelligent animals. This belief has become a central argument against whaling (killing whales for food or other commercial reasons).
Many species of cetaceans, such as the Killer Whale (Orcinus Orca), travel in large pods and rely on each other's help to find food. For example, in the Arctic Ocean, Orcas have been documented tipping small ice patches, so that a seal resting upon it can slide down into a waiting Orca's mouth. Group attacks and feeding are successful tactics and intelligence features used by whales.
There is no universally agreed definition of "intelligence." One commonly used definition is "the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience." Proponents of whale intelligence cite the social behavior of whales and their apparent capacity for language as evidence of a sophisticated intellect. Given the radically different environment of whales and humans, and the size of whales compared to dolphins or chimpanzees, for instance, it is extremely difficult to test these views experimentally.
One traditional indicator of intelligence is brain capacity, since humans have bigger brains than most other animals. Whales have the largest brain of any animal. A typical sperm whale brain weighs about 7.8 kg, whereas a typical human brain weighs about 1.5 kg. While it may seem that this would indicate that five times greater intelligence, in mammals brain size is in approximate ratio to body size, and most of the extra capacity is used to manage the larger body.
A more precise indicator is the brain-body ratio: the size of the brain compared to body mass. Here humans have a decisive advantage. A human brain comprises about 2 percent of the human body mass, while the sperm whale's brain comprises only 0.02 percent of its body mass. A cow's brain is four times as large as a whale's on this measurement. On the other hand, a large proportion of a whale's body mass is blubber, which requires no brainpower, and this distorts the ratio somewhat. Nevertheless, it is clear that brain size is not a decisive criterion. Hummingbirds have an even higher brain-to-body ratio than humans.
The next consideration is the structure of the brain. It is generally held that the growth of the neocortex, both absolutely and relative to the rest of the brain, has been responsible for the evolution of intelligence, however defined. In most mammals, the neocortex has six layers, and its different functional areas (vision, hearing, etc) are sharply differentiated. The whale neocortex, on the other hand, has only five layers, and there is little differentiation of these layers according to function. This has led some to argue that the whale brain has not significantly evolved since the distant ancestors of the whale took to a marine lifestyle about 50 million years ago.
On the other hand, whales have a large area of silent parietal and frontal lobe in their brains. In humans, this area of the brain is used for assessing the past and forecasting the future.
Whales have a sophisticated social system and communications. Their communication system contains some of the elements of true language, although our knowledge of whale communications is not very advanced. We do know, however, that whales can transmit two sonic probes and send them at any direction at the same time, above, below, ahead, or behind. With respect to dolphins, these animals will respond when spoken to in English and can alter their vocal frequencies to match humans. Many other animals, including insects, have complex social systems, and many others, such as birds, have sophisticated communications. Whales also have very acute hearing, which gives them advanced echo-location capacities analogous to sonar—but so do bats.
Determining how intelligent whales and dolphins actually are will require further research.
Some interesting observations, though, include the fact that dolphins have been able to understand over 50 different English words spoken by humans, but humans have yet to understand anything spoken by dolphins. Whales and dolphins have created social systems with no classes, castes, or wars. Killer whales do not kill humans. Humans have not been able to do the same in refraining from creating classes, castes, wars, and killing other humans.
Whales and humans
There are many stories going back to the ancient Greeks and continuing to the present day of cetaceans, specifically dolphins, saving or aiding humans. Some of these accounts are about dolphins that push a person to shore or a drowning person to the surface for air, or cetaceans that guide ships. There is even an account of dolphins in New Zealand circling a group of swimmers to protect them from a great white shark.
Dolphin assisted therapy is now being used to treat a number of human diseases, including autism.
Humans have not always been as kind to whales and dolphins. Today, most species of large whales are endangered as a result of large-scale whaling during the nineteenth and twentieth centuries. For centuries large whales have been hunted for oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales). In the twentieth century, humpback whales were so intensively hunted that 200,000 were killed in the Southern Hemisphere alone and 95 percent of the population was reduced (Whale Trust 2006). By the middle of the twentieth century, whaling left many populations nearly or fully extinct. The International Whaling Commission introduced an open-ended moratorium on all commercial whaling in 1986. 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.
Several species of small whales are caught as bycatch (an incidental catch) in fisheries trying for other species. In many countries, small whales are still hunted for food, oil, meat or bait.
Environmentalists have long argued 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 beachings and to signs that the beached whales have experienced decompression sickness (Jepson et al. 2003; see also Kirby 2003).
Mass whale beachings occur in many species, mostly beaked whales that use echolocation systems for deep diving. The frequency and size of beachings around the world, recorded over the last 1,000 years in religious tracts and more recently in scientific surveys, has been used to estimate the changing population size of various whale species by assuming that the proportion of the total whale population beaching in any one year is constant. Despite the concerns raised about sonar, which may invalidate this assumption, this population estimate technique is still popular today. Some researchers in the area (Talpalar and Grossman 2005) support the view that it is the combination of the high pressure environment of deep-diving with the disturbing effect of the sonar that causes decompression sickness and stranding of whales. Thus, an exaggerated startle response occurring during deep diving may alter orientation cues and produce rapid ascent.
Following public concern, the United States Defense Department has been ordered by the United States Judiciary to strictly limit use of its Low Frequency Active Sonar during peacetime. The European Parliament has requested that EU members refrain from using the powerful sonar system until an environmental impact study has been carried out.
Conservationists are concerned that seismic testing used for oil and gas exploration may also damage the hearing and echolocation capabilities of whales. They also suggest that disturbances in magnetic fields caused by the testing may also be responsible for beaching (Weilgart 2006).
Whales in culture
Whales have often appeared in literature. In the ancient work Beowulf, the sea was described as "whale's road." In the Bible, there is a reference to the whale as the Leviathan, and the statement that “Upon Earth there is not his like who is made without fear” (Job 41). The Bible also has the famous story of Jonah being swallowed by the big fish (whale) a story also mentioned in the Qur'an as well.
The hunting of whales is the subject of one of the classics of the English language literary canon, Herman Melville's Moby-Dick. Melville classified whales as "a spouting fish with a horizontal tail," despite science suggesting otherwise the previous century. Melville acknowledged "the grounds upon which Linnaeus would fain have banished the whales from the waters," but says 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." Melville's book is an extraordinary work—part adventure story, part metaphysical allegory, and part natural history; it is essentially a complete summary of nineteenth-century knowledge about the biology, ecology, and cultural significance of whales.
Beyond literature, the whale has been a popular fixture in many cultures. Some cultures associate some level of divinity with the whale, such as in some places in Ghana and Vietnam where funerals are occasionally held for beached whales. In Vietnam, this is a throwback to Vietnam's ancient sea-based, Austroasiatic culture. An Inuit saying is “We like the way whales think,” and other Native Americans traditions refer to the whale as a symbol of the wisdom of longevity. 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 symposiums.
ReferencesISBN links support NWE through referral fees
- Carwardine, M. 2000. Whales, Dolphins and Porpoises. Dorling Kindersley. ISBN 0751327816
- Hamby, W. 2004. Ultimate Sound Pressure Level Decibel Table. http://www.makeitlouder.com/Decibel%20Level%20Chart.txt (accessed June 20, 2006).
- Jepson, P. D. et al. 2003. Gas-bubble lesions in stranded cetaceans. Nature 425:575-576.
- Kirby, A. 2003. Sonar 'may cause whale deaths'. BBC News October 8, 2003. http://news.bbc.co.uk/2/hi/science/nature/3173942.stm
- Talpalar, A. E., and Y. Grossman. 2005. Sonar versus whales: Noise may disrupt neural activity in deep-diving cetaceans. Undersea Hyperb Med. 32(2):135-9.
- Weilgart, L. 2006. Seismic testing and the impacts of high intensity sound on whales. http://www.sustainability.ca/Docs/Impact%20of%20Seismic%20Surveys%20on%20Whales.pdf (accessed June 20, 2006).
- Whale Trust. 2006. http://www.whaletrust.org/whales_sub/behav.htm (accessed June 20, 2006).
New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:
The history of this article since it was imported to New World Encyclopedia:
Note: Some restrictions may apply to use of individual images which are separately licensed.