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What is a whale?
A whale is any of the larger aquatic mammals belonging to the order Cetacea. Though the term can refer to any cetacean, it is generally applied to those longer than 3 meters (10 feet). As mammals, whales breathe air, are warm-blooded, give live birth, nurse their young with milk, and have hair. They are fully aquatic, with flippers and tail flukes, and must surface to breathe. Whales are distributed throughout the worldâs oceans and seas, from the Equator to the polar ice. The blue whale can reach over 30 meters and 200 metric tons, making it the largest known animal.
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Are whales mammals or fish?
Whales are mammals, not fish. They share key traits with other mammals: they breathe air, are warm-blooded, give birth to live young, nurse their young with milk, and have hair (though often only as whiskers). Whales are fully aquatic mammals with adaptations such as flippers and tail flukes. They must surface to breathe, expelling air in an explosive blow. The largest whales can reach over 30 meters in length and weigh over 200 tons.
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What makes a whale a mammal?
Whales are mammals because they share key characteristics with other members of the class Mammalia. Like all mammals, whales breathe air, are warm-blooded, give live birth, and nourish their young with milk from mammary glands. Though most adult whales have very little hair, they are born with it.
Other defining traits of mammals include a four-chambered heart, a muscular diaphragm separating the heart and lungs from the abdominal cavity, and a chain of three tiny bones that transmit sound waves across the middle ear. Blubber helps whales maintain body temperature in water.
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How do whales breathe if they live in water?
Whales are mammals that breathe air. Unlike fish, who use gills to extract oxygen from water, whales have lungs and must surface to breathe. Whales breathe through their blowholes, evacuating their lungs in an explosive breath called a blow.
Cetaceans use up to 80 percent of their lung volume in a single breath, whereas humans only use 20 percent. Larger whales, such as minke and humpback whales, surface every 10 to 15 minutes to breathe. A Cuvierâs beaked whale holds the record for breath-holding, with one reported to have remained underwater for 222 minutes.
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What are some different types of whales?
Whales are categorized into two primary types: toothed whales (Odontoceti) and baleen whales (Mysticeti).
- Toothed whales include dolphins, porpoises, and sperm whales. They possess simple, conical teeth used for grasping prey like fish and squid, which they swallow whole.
- Baleen whales include humpback, gray, and blue whales. Instead of teeth, they have baleen plates, which are unique structures made of keratin that they use to filter small prey, like krill and plankton, from the water.
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How do whales take care of their young?
Whales, being mammals, share several key traits with other mammals, including how they care for their young. After about a year-long gestation, a whale mother gives birth to a single calf, tail first. Whale mothers nurse their young with extremely rich milk, which has a fat content of around 50%. Calves are weaned at roughly 6 months to a year but continue to grow rapidly for several years.
Cetaceans are social animals, and the bond between mother and calf forms the core of their social structure. Sometimes healthy whales will care for a sick or wounded whale.
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whale, any of the larger species of aquatic mammals belonging to the order Cetacea. The term whale can be used in reference to any cetacean, including porpoises and dolphins, but in general it is applied to those more than 3 metres (10 feet) long. An exception is the 2.7-metre dwarf sperm whale (Kogia simus), so called for its otherwise striking resemblance to its larger namesake. Whales are the heaviest known animals, living or fossil, reaching a maximum size in the blue whale (Balaenoptera musculus) of perhaps more than 30 metres and 200 metric tons (220 short [U.S.] tons). Large predatory whales, including the killer whale, are often considered to be the apex predators (meaning they have no natural predators or enemies) of their marine environments.
Whales are distributed throughout the worldâs oceans and seas, from the Equator to the polar ice, except for the landlocked Caspian and Aral seas. They are mammals, and they share the defining traits of that group: they breathe air, are warm-blooded, give live birth, suckle their young on milk, and have hair. All are entirely aquatic, with specialized adaptations such as flippers and tail flukes for living in water. Whales must surface regularly to breathe, evacuating their lungs more completely than most mammals in an almost explosive breath known as a blow. Blows are visible because water vapour in the whaleâs hot breath condenses when the blow is released.
Despite living in a medium that has much greater thermal conduction characteristics than air, whales, like other mammals, must regulate their body temperature. Hair, however, is restricted to the head, appearing mainly as isolated whiskers (vibrissae) near the mouth and blowhole. Blubber serves as an insulating layer to protect small whales from hypothermia. Large whales have the opposite problem in that they can produce too much heat; they possess elaborate thermoregulation mechanisms to prevent overheating.
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Because of the restricted utility of vision underwater, whales use sound to perceive and interpret their environment and to communicate, sometimes over vast distances. Biologists have computed that the 10-hertz sounds of fin whales (Balaenoptera physalus), for example, can travel over 1,800 km (1,100 miles). Toothed whales can produce sounds and interpret their reflections via active echolocation. The extent to which baleen whales have this ability is unknown.
Following internal fertilization, female whales are pregnant for about a year. The young are relatively large when bornâone-third to one-half the length of the mother. They are nursed for about six months on extremely rich milk containing almost 50 percent fat. Whales have one pair of nipples located at the rear of the abdomen near the genital opening.
The first fossil whales are known from rocks approximately 50 million years old (Early Eocene Epoch). These members of the extinct suborder Archaeoceti are the primitive whales from which modern whales are derived. They show many similarities to terrestrial mammals, including a differentiated dentition (heterodonty) consisting of incisors, canines, premolars, and molars. Archaeocetes gave rise to the living suborders: the baleen whales (suborder Mysticeti) and the toothed whales (suborder Odontoceti).
Mysticetes have baleen plates and take small prey by the mouthful, mainly in the form of drifting (planktonic) crustaceans such as copepods and krill, but they also occasionally consume small schooling fish or squid. One interesting departure from this pattern is the gray whale (Eschrichtius robustus), which commonly eats shrimp and other bottom-dwelling creatures: it scoops up mud and strains it through the baleen plates, retaining its food. Odontocetes have simple teeth (homodonty) and pursue individual squid, fish, and other prey. The largest odontocete, the sperm whale (Physeter macrocephalus), occasionally feeds on giant squid.
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Humans have long utilized stranded whales as a food resource, and historically whales were hunted for whale oil and baleen. In the early 20th century, as demand increased and technology enabled meat to be frozen at sea, whales began to be taken in larger numbers for human consumption and for specialty products. Scientific concern over the increased catch of whales in the Southern Hemisphere in the 1930s led to the ratification of the International Whaling Convention and the founding of the International Whaling Commission in 1946. Through the years this agency has acted to moderate whaling, and it instituted a moratorium on commercial whaling in the late 1980s. Some whaling still occurs under special permit. Native peoples are also allowed to continue traditional whale hunting that has been a part of their culture.