What is the largest whale?

Quick Answer

The absolute largest whale is the Blue Whale (Balaenoptera musculus). It is not only the largest whale species currently inhabiting the ocean, but it is also the heaviest animal known to have ever lived, surpassing even the largest titanosaurs of the prehistoric era.

While sizes vary between the subspecies found in the Northern and Southern Hemispheres, Antarctic blue whales are generally larger. The largest specimen scientifically measured was a female in the Southern Ocean that stretched 110 feet (33.58 meters). In terms of mass, the heaviest recorded blue whale weighed an astounding 190 metric tonnes (418,878 pounds). To put this immense magnitude into perspective, a single blue whale can weigh as much as 33 adult African elephants combined.

While the blue whale holds the title for overall size, the Sperm Whale is the largest toothed whale, and the Fin Whale ranks as the second-largest animal on the planet.

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Detailed Explanation

The sheer scale of the blue whale is difficult to comprehend without breaking down the biology and physics that allow such an animal to exist. As a marine mammal, the blue whale relies on the buoyancy of saltwater to support its massive bulk—a skeletal structure that would likely collapse under its own weight on land.

Dimensions and Measurements

In the world of Size & Weight, the blue whale is the undisputed champion. Adult blue whales typically range between 80 to 100 feet (24 to 30 meters) in length.

• Length: Equivalent to three school buses lined up bumper-to-bumper or the length of an NBA basketball court.
• Weight: Ranging from 100 to 150 tons on average, with maximums reaching nearly 200 tons.

It is important to note that female blue whales are generally larger than males, a trait known as reverse sexual dimorphism, which is common among baleen whales. The females require the additional body mass to support the energetic costs of pregnancy and lactation.

Anatomical Superlatives

The internal anatomy of Balaenoptera musculus scales proportionally with its exterior dimensions, resulting in biological statistics that seem almost mythical:

• The Heart: A blue whale’s heart is the largest of any animal, weighing roughly 400 pounds (180 kg). While the popular myth that a human could swim through its arteries is an exaggeration, a human baby could certainly crawl through the aorta (the main artery), which is about 9 inches (23 cm) in diameter.
• The Tongue: Its tongue weighs approximately 2.7 metric tons, which is roughly the weight of a fully grown female African elephant.
• The Mouth: Despite its size, the blue whale has a throat roughly the size of a grapefruit. It cannot swallow large objects. However, its mouth can hold up to 90 metric tons of water and food during a single lunge feed.

Growth Rates

The growth trajectory of a blue whale is the fastest in the animal kingdom. A calf emerges after a gestation period of nearly a year, already measuring 23 feet (7 meters) in length and weighing up to 3 tons. Feeding on its mother’s incredibly rich milk (which is 35-50% fat), the calf gains approximately 200 pounds (90 kg) every single day—or about 8-10 pounds an hour—during its first year of life.

The Competition: Second and Third Place

While the blue whale is the apex of size, other species are incredibly massive:

1. Fin Whale (Balaenoptera physalus): The “Greyhound of the Sea” is the second-largest whale, reaching lengths of up to 85 feet (26 meters). They are sleeker and faster than blue whales but significantly lighter, maxing out around 80 tons.
2. Sperm Whale (Physeter macrocephalus): This is the largest toothed predator on Earth. While shorter (up to 67 feet/20.5 meters), they are bulkier than some baleen whales of similar length.
3. Right Whale: Specifically the North Pacific Right Whale, these animals are extremely robust and rotund, sometimes weighing more than fin whales despite being shorter.

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Comparative Analysis: Scales of Giants

To truly understand what is the biggest whale, it helps to compare the blue whale against other marine giants, humans, and mechanical objects. The table below illustrates the hierarchy of size within the marine environment.

Marine Giants Comparison Table

Species / Object	Classification	Avg. Max Length	Avg. Max Weight	Comparison Note
Blue Whale	Baleen Whale	30 m (98 ft)	199 tonnes	Heavier than 2,500 humans.
Fin Whale	Baleen Whale	26 m (85 ft)	72 tonnes	Long and slender; 2nd largest animal.
Sperm Whale	Toothed Whale	20.5 m (67 ft)	57 tonnes	Largest brain of any animal.
Whale Shark	Fish (Shark)	18.8 m (62 ft)	21 tonnes	Largest non-mammalian vertebrate.
Humpback Whale	Baleen Whale	16 m (52 ft)	30 tonnes	Roughly the size of a city bus.
Killer Whale	Toothed Whale	9.8 m (32 ft)	10 tonnes	Actually the largest member of the dolphin family.
Boeing 737-900	Aircraft	42 m (138 ft)	79 tonnes (Empty)	Blue whales are shorter but often twice as heavy.
Argentinosaurus	Dinosaur	35 m (115 ft)	~80-100 tonnes	The Blue Whale is nearly double the weight of the largest dinosaur.

Why Aren’t They Bigger?

Biologists believe there is a physiological limit to how big a whale can get, largely dictated by their Diet & Food intake. Blue whales are obligate filter feeders, relying almost exclusively on krill. They feed by lunge-feeding—accelerating into a swarm of krill with their mouths open. This requires immense energy.

Recent research suggests that the energy required to lunge-feed limits their maximum size. If a blue whale were significantly larger, the metabolic cost of accelerating that mass to catch prey would exceed the energy gained from the food itself. Essentially, the blue whale exists right at the mathematical limit of bio-energetic efficiency for a filter feeder.

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Why This Matters

The immense size of the blue whale is not just a trivia fact; it is a critical component of ocean health. Because of their colossal mass, blue whales act as massive carbon sinks.

Carbon Sequestration

When a blue whale dies and sinks to the ocean floor (a phenomenon known as “whale fall”), it sequesters an average of 33 tons of carbon dioxide, taking it out of the atmosphere for centuries. In contrast, a tree absorbs only about 48 pounds of CO2 a year. The restoration of blue whale populations to pre-whaling levels would be equivalent to planting millions of trees in terms of carbon capture.

The Whale Pump

Furthermore, these massive animals cycle nutrients. Because they feed at depth and defecate near the surface, they bring essential nutrients like iron and nitrogen up from the deep. This “whale pump” stimulates the growth of phytoplankton, which in turn feeds the krill, creating a positive feedback loop. The removal of 99% of blue whales during the commercial whaling era didn’t just remove the animals; it damaged the productivity of the entire Southern Ocean ecosystem.

Conservation Status

Despite their size, they are vulnerable. Blue whales are currently listed as Endangered on the IUCN Red List. They are slowly recovering from 20th-century whaling, but they face modern threats including ship strikes, entanglement in fishing gear, and climate change affecting krill populations. Understanding their size helps researchers calculate population bio-energetics and advocate for shipping lane adjustments to prevent collisions. For more on this, read our guide on Conservation.

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Frequently Asked Questions

Is the Megalodon bigger than the Blue Whale? No. The Megalodon (Otodus megalodon) was a massive prehistoric shark, but estimates place its maximum length between 50 and 60 feet (15-18 meters). The modern blue whale is roughly twice as long and several times heavier than the largest estimates for Megalodon.

What is the biggest thing a Blue Whale can eat? Despite being the largest animal, the blue whale has a very narrow esophagus (throat), measuring only about 4 to 8 inches in diameter. They cannot swallow anything larger than a grapefruit or a melon. They subsist almost entirely on tiny crustaceans called krill.

Has any animal ever been bigger than the Blue Whale? Paleontologists have analyzed the fossil record extensively, including the largest sauropod dinosaurs like Argentinosaurus and Patagotitan. While some dinosaurs may have matched or slightly exceeded the blue whale in length (due to long necks and tails), none came close to the blue whale’s mass. The aquatic environment supports weight that terrestrial gravity would not allow.

How big is a Blue Whale’s heart compared to a human? A blue whale’s heart weighs approximately 400 pounds (180 kg) and is about the size of a bumper car. In comparison, an adult human heart weighs roughly 10-12 ounces (300 grams) and is the size of a fist.

Do Blue Whales sleep? Like other cetaceans, blue whales engage in unihemispheric slow-wave sleep, resting one half of their brain at a time while the other remains alert to breathe and monitor the environment. For more details, see how do whales sleep.

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Sources and Further Reading

The information in this article is verified against the world’s leading marine science databases and conservation organizations.

1. NOAA Fisheries: The National Oceanic and Atmospheric Administration provides authoritative data on blue whale conservation status, biology, and population estimates.
2. National Geographic: Offers comprehensive visual and biological profiles of Balaenoptera musculus, including verified measurements of the largest specimens.
3. Smithsonian Ocean Portal: Detailed analysis of whale evolution and the “whale pump” ecosystem services provided by large baleen whales.
4. Whale and Dolphin Conservation (WDC): A leading global charity dedicated to the protection of whales, providing specific data on species recovery and threats.