“The blue whale is the largest animal ever known to have lived.”
The blue whale is the largest animal known to have ever lived, reaching about 30 metres and 150 tonnes. It filters tiny krill from cold and temperate oceans and, after the era of industrial whaling, is listed as Endangered.
By An Nguyen · Published · Updated
Balaenoptera musculus Cetacea Balaenopteridae
Measured against the 176 species profiled on this site. Each figure is converted to one unit system from the published range on the page, so the ranks are computed, not quoted.
| Measure | This species | Rank here | Exceeds |
|---|---|---|---|
| Body mass | 200 t | #1 of 176#1 of 90 Mammalia | 100% |
| Body length | 30.48 m | #1 of 176#1 of 90 Mammalia | 100% |
| Top speed | 48.3 km/h | #36 of 75#23 of 46 Mammalia | 46% |
| Lifespan in the wild | 90 yr | #4 of 169#1 of 85 Mammalia | 98% |
Closest in body mass
Ranks use the upper end of each published adult range, so they compare typical large adults rather than records, and metrics with no published number are left out rather than estimated. The full table is downloadable from the species dataset, and any two species can be put side by side in the comparison tool.
Browse images of blue whale across habitat, behavior, anatomy, and life stages, including a scientific size-comparison chart and a range map.
Click any photo to view it larger. 8 images available.
Core article
A closer look at habitat, diet, behavior, reproduction, and conservation.
The blue whale (Balaenoptera musculus) is the largest animal known to have ever lived — commonly 80 to 100 feet long and up to about 200 tons. Yet it lives on some of the ocean's smallest prey: krill, shrimp-like crustaceans that swarm in dense patches. The whale gulps krill-laden water into an expanding throat pouch, then forces the water back out through baleen plates and swallows what's left. It occurs in every ocean, migrating between rich high-latitude feeding grounds and warmer breeding waters; see why blue whales are so big for how such size is even possible.
The numbers strain belief: the tongue alone can weigh as much as an elephant, and the heart is roughly the bulk of a small car, pumping some 220 gallons of blood a beat. The body is a tapered, streamlined cylinder, smooth and mottled slate-blue — light refracting through water lends it the luminous blue that names it. It has no teeth; instead the upper jaw carries 300 to 400 fringed baleen plates of keratin, the same material as fingernails. From chin to navel run 50 to 90 elastic throat pleats that let the mouth balloon to engulf a volume of water as heavy as the whale itself in one gulp. Surfacing, it blows a 30-foot column of misty, pressurized breath through twin blowholes. It belongs to the rorqual family Balaenopteridae, alongside the fin whale and the humpback whale.
Blue whales are found in every major ocean basin, from the Southern Ocean and Arctic to tropical seas, favouring deep, open water where cold, nutrient-rich upwellings feed krill. They are strongly migratory: in summer they move to polar and sub-polar waters to gorge on krill blooms fuelled by endless daylight, then travel as far as 3,000 miles to warm tropical waters in winter to breed and calve, living off blubber reserves the whole way. Recognized subspecies include the Antarctic, Northern, and smaller Pygmy blue whale of the Indian and South Pacific Oceans.
The blue whale is a carnivore that feeds primarily on krill, eating up to 4 tons a day in the summer feeding season. During lunge feeding, it accelerates into a dense swarm, opens its lower jaw, and expands the throat pleats to take in krill and water. The mouth then closes and the tongue forces water out through the baleen, retaining the krill. Each high-drag lunge slows the whale and requires substantial cardiovascular effort.
Blue whales are largely solitary, sometimes forming loose pairs or brief gatherings where krill is thick, and they lack the tight, lasting pods of toothed whales like orcas or sperm whales. They are among the loudest animals on Earth, producing sustained, very low-frequency moans and pulses of 10 to 40 Hertz — some below human hearing. In the right ocean conditions these calls carry for great distances, likely helping widely scattered whales keep contact and find mates.
Reproduction is a huge maternal investment. Gestation runs about 10 to 12 months, and calving happens in warm tropical water in winter, where a newborn with little blubber won't chill. A calf is already about 25 feet long and up to 3 tons at birth, and drinks milk that is 40 to 50% fat, gaining around 200 pounds a day for the first six to eight months. It is weaned near 50 feet long, usually as the mother returns to polar feeding grounds. Blue whales mature at 5 to 10 years and, with no predator but coordinated orca packs that target calves, can live 80 to 90 years.
The blue whale is Endangered, largely a legacy of 20th-century whaling. Too fast for early whalers, it became a target once explosive harpoons and steam-powered factory ships arrived: more than 340,000 were killed in the Antarctic in the first half of the century, cutting the regional population by over 99%. Fully protected by the International Whaling Commission since 1966, the global population is recovering slowly, now roughly 10,000 to 25,000. Modern threats remain — fatal ship strikes where shipping lanes cross feeding and migration routes, rising ocean noise from sonar, seismic oil surveys, and shipping that masks their calls, and climate change that may shift the krill their entire existence depends on.
Kingdom
Animalia
Phylum
Chordata
Class
Order
Cetacea
Family
Genus
Balaenoptera
Species
B. musculus
The blue whale is the largest animal ever known to have lived.
A blue whale's tongue can weigh as much as an elephant.
Blue whales eat mostly tiny krill, not large fish or seals.
A blue whale's blow can shoot 30 feet into the air.
Blue whale calls can travel hundreds of miles underwater.
A newborn blue whale calf can gain about 200 pounds per day.
Select a question to reveal the answer.
Many adults reach about 80 to 100 feet long and can weigh up to 200 tons. That is longer than a school bus and heavier than many elephants combined.
Blue whales eat mostly krill, which are tiny shrimp-like animals. They also swallow small fish and copepods when feeding.
Blue whales live in oceans around the world. They migrate between cold feeding areas near the poles and warmer waters where they breed.
Like all mammals, blue whales must breathe air. They come to the surface, open two blowholes on top of the head, and exhale a tall spout of mist.
No. A blue whale's throat is too narrow to swallow a person. Its baleen is built to strain tiny prey, not large animals.
Blue whales usually swim at a steady, slow pace. They can sprint faster for short distances, sometimes reaching around 30 miles per hour.
Yes. Blue whales are listed as Endangered after centuries of whaling. Protecting oceans from ship strikes, noise, and pollution helps them recover.
They look blue-gray underwater because of their skin color and the way light scatters in the ocean. On dry land, their skin looks more gray than bright blue.
Yes, a blue whale is a mammal. It breathes air through lungs, gives birth to a live calf, produces milk, and must surface to use the two blowholes on top of its head.
A blue whale has a long streamlined body, mottled blue-gray skin, a small dorsal fin, paired blowholes, and expandable throat grooves. Baleen plates replace teeth and filter krill from engulfed seawater.
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