- Also called:
- sulfur-bottom whale
- Related Topics:
- charismatic megafauna
- rorqual
- What is the largest animal on Earth?
- On the Web:
- Aquarium of the Pacific - Blue Whale (Oct. 25, 2026)
blue whale
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What is a blue whale?
The blue whale (Balaenoptera musculus) is the largest animal on Earth, reaching up to 98 feet (30 meters) long and weighing 150 tons. As mammals, blue whale calves drink 50 to 150 gallons of their mother’s milk per day, gaining about 200 pounds daily.
Blue whales are blue-gray with lighter gray spots. They are baleen whales, possessing baleen plates instead of teeth, which they use to feed on krill. Blue whales live in all oceans, save the Arctic, and spend summers in polar waters feeding before migrating to the Equator to breed.
Blue whales communicate through vocalizations, which helps them share information and navigate.
Hunted nearly to extinction in the 20th century, commercial whaling was banned in 1966. Today, populations are recovering; however, the IUCN still lists the blue whale as an endangered species.
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Why is the blue whale considered a mammal?
The blue whale is considered a mammal because it possesses the defining characteristics of mammals. These include:
* Bearing live young (viviparous) and nourishing their young with milk from mammary glands
* Being warm-blooded and breathing air
* Possessing hair (though significantly reduced except during the fetal stage)Additionally, blue whales have a muscular diaphragm separating the heart and lungs from the abdominal cavity, and they lack a nucleus in their mature red blood cells, both of which are mammalian traits. As the largest mammal on Earth, the blue whale can weigh up to 200 tons and reach lengths of 30 meters.
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How big can a blue whale grow?
The blue whale (Balaenoptera musculus) is the largest animal on Earth, and the largest animal to have ever existed. Blue whales can weigh approximately 150 tons and stretch over 30 meters (98 feet) in length. There are reports of blue whales reaching lengths of 33 meters and weights of about 200 tons. The largest accurately measured blue whale was a 29.5-meter female that weighed 180 metric tons. Newborn blue whales can weigh anywhere from 2.5 to 4 tons and can reach 100 to 120 tons in adulthood.
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What do blue whales eat?
Blue whales are baleen whales that feed on tiny marine organisms. They consume shrimplike crustaceans called krill, as well as copepods, plankton, and small fish.
Blue whales are filter feeders that take in large mouthfuls of water, then use baleen plates to trap food. Bristly edges on the plates catch food while letting water flow back out. A single adult blue whale can consume up to 8 tons of krill each day during the summer in polar waters.
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How do blue whales communicate with each other?
Blue whales communicate through vocalizations, using low-frequency sounds that are among the loudest made by any animal. These sounds can travel across entire ocean basins, potentially enabling communication over vast distances.
Blue whales are baleen whales, and like other baleen whales, they use their larynx to vocalize. Though it was once thought that the cetacean larynx couldn't generate sound because it lacks vocal cords, baleen whales have laryngeal pouches that modify sound. These vocalizations are used to share information and possibly for long-range echolocation to help with orientation and navigation.
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Why are blue whales endangered and what efforts are being made to protect them?
Blue whales are endangered due to 20th-century whaling, which reduced their population by up to 90%. Commercial hunting was banned in 1966, but fewer than 25,000 exist today.
The U.S. National Marine Fisheries Service created a recovery plan in 1998 that uses photo databases and collects genetic and migration data to understand the species better. The International Whaling Commission (IWC) was established in 1946 to conserve whale stocks. Blue whales remain at risk from ship collisions and entanglement in fishing nets.
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blue whale, (Balaenoptera musculus), the most massive animal ever to have lived, a species of baleen whale that weighs approximately 150 tons and may attain a length of more than 30 metres (98 feet). The largest accurately measured blue whale was a 29.5-metre female that weighed 180 metric tons (nearly 200 short [U.S.] tons), but there are reports of 33-metre catches that may have reached 200 metric tons. Their hearts, which typically weigh about 180 kg (roughly 400 pounds), are the largest of any animal.
The blue whale is a cetacean and is classified scientifically within the order Cetacea as a rorqual (family Balaenopteridae) related to the gray whale (family Eschrichtiidae) and the right whales (Balaenidae and Neobalaenidae) of the baleen whale suborder, Mysticeti.
Blue whales are blue-gray in colour with lighter gray mottling in the form of large spots, which appear as if they were dabbed on with a huge paintbrush. The lower surfaces of the flippers are lighter gray or white in some instances. The blue whale has been called the sulfur-bottom whale because of the yellowish underside of some individuals that is reminiscent of the pale yellow colour of that chemical element; this coloration is imparted by certain algae (diatoms) living on the whale’s body. The blue whale has a wide head, a small dorsal fin located near the fluke, and 80–100 long grooves running lengthwise down the throat and chest. Its mouth contains up to 800 plates of short, wide, black baleen, or “whalebone,” with thick, coarse bristles used for catching food. Females are generally larger than males, and the largest animals live in the Southern Ocean around Antarctica.
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The blue whale is found alone or in small groups in all oceans, but populations in the Southern Hemisphere are much larger. In the Northern Hemisphere, blue whales can be seen regularly in the Gulf of St. Lawrence and off the coasts of Monterey, California, and Baja California, Mexico. They spend the summer in polar waters, feeding on shrimplike crustaceans called krill. During a dive, the blue whale may engage in a series of turns and 360° rolls to locate prey and rapidly reorient its body to sweep up large concentrations of krill in a single open-mouthed lunge. A single adult blue may consume as much as eight tons of krill per day. In the winter blue whales move toward the Equator to breed. After a gestation of about 12 months, one calf about 8 metres (about 26 feet) long is born in temperate waters. While nursing, calves gain up to 90 kg (about 198 pounds) per day on the rich milk of their mothers. Young are weaned after seven to eight months, when they have reached a length of about 15 metres (about 49 feet).
Once the most important of the commercially hunted baleen whales, the blue whale was greatly reduced in numbers during the first half of the 20th century. In the 1930–31 season alone the worldwide kill of blue whales exceeded 29,000. The species has been protected from commercial whaling since the mid-1960s. Populations of blue whales appear to be recovering and are estimated worldwide at between 10,000 and 25,000 animals. However, the International Union for Conservation of Nature still lists the blue whale as an endangered species.