Blue Whale Facts

Photos and information about the world's largest animal

Balaenoptera musculus

NOAA Photo Library / Wikimedia Commons / Public Domain 

The blue whale is the largest animal on Earth. Learn how big these whales get and more facts about these huge marine mammals.

Blue Whales Are Mammals

Blue Whale, Balaenoptera musculus.

Doug Perrine / Photolibrary / Getty Images

Blue whales are mammals. We are mammals, too, so both humans and blue whales are endothermic (commonly called "warm-blooded"), give birth to live young and nurse their young. Whales even have hair.

Because blue whales are mammals, they breathe air through lungs, just like we do. When blue whales exhale, the air rises more than 20 feet and can be seen from quite a distance. This is called the whale's blow or spout.

Blue Whales Are Cetaceans

Blue whales on the surface. California, Gulf of the Farallones

Dan Shapiro / NOAA Photo Library / Wikimedia Commons / CC BY 2.0

All whales, including blue whales, are cetaceans. The word cetacean comes from the Latin word cetus, which means "a large sea animal," and the Greek word ketos, which means "sea monster."

Cetaceans propel themselves but undulating their tail up and down. They have blubber to help insulate their bodies. They also have excellent hearing, and adaptations for surviving in deep water, including collapsible rib cages, flexible skeletons, and a high tolerance for carbon dioxide in their blood.

Blue Whales Are the Largest Animals on Earth

Adult blue whale (Balaenoptera musculus) from the eastern Pacific Ocean.

NMFS Northeast Fisheries Science Center (NOAA) / Wikimedia Commons / Public Domain

Blue whales are the largest animal on Earth today and are thought to be the largest animal that has ever lived on Earth. Swimming in this ocean right now, there are blue whales who can grow to more than 90 feet in length and over 200 tons (400,000 lbs) in weight. Imagine a creature the size of 2 1/2 school buses laid end-to-end and you'll get a sense of the size of the blue whale. The maximum weight of one blue whale is the same weight as about 40 African elephants.

A blue whale's heart alone is about the size of a small car and weighs about 1,000 pounds. Their mandibles are the largest single bones on Earth.

Blue Whales Eat Some of the Smallest Organisms on Earth

Krill on Finger

Sophie Webb / NOAA / Wikimedia Commons / CC0 1.0 

Blue whales eat krill, which average about 2 inches in length. They also eat other small organisms, such as copepods. Blue whales can consume 4 tons of prey per day. They can eat huge amounts of prey at once thanks to their baleen - 500-800 fringed plates made of keratin that allow the whale to gulp their food, but filter seawater out.

Blue whales are part of the group of cetaceans called the rorquals, which means they are related to fin whales, humpback whales, sei whales, and minke whales. Rorquals have grooves (the blue whale has 55-88 of these grooves) that run from their chin to behind their flippers. These grooves allow the rorquals to expand their throat while feeding to accommodate huge amounts of prey and seawater before the water is filtered back into the ocean via the whale's baleen.

A Blue Whale's Tongue Weighs About 4 Tons

Skeleton and taxidermy preparation of a young male blue whale (Balaenoptera musculus) as on display at the 'Göteborg Natural History Museum', Sweden.

Dr. Mirko Junge / Wikimedia Commons / CC BY-SA 4.0 

Their tongue is about 18 feet long and can weigh up to 8,000 pounds (the weight of an adult female African elephant). A 2010 study estimated that when feeding, a blue whale's mouth opens so wide, and is so large, that another blue whale could swim into it.

Blue Whale Calves Are 25 Feet Long When Born

A mother Blue Whale swims with her calf in clear tropical waters.

CoreyFord / Getty Images

Blue whales give birth to a single calf, every 2-3 years after a gestation period of 10-11 months. The calf is about 20-25 feet long and weighs about 6,000 pounds at birth.

Blue Whale Calves Gain 100-200 Pounds Per Day While Nursing

A blue whale calf with its mother

tane-mahuta / Getty Images 

Blue whale calves nurse for about 7 months. During this time, they drink about 100 gallons of milk and gain 100-200 pounds per day. When they are weaned at 7 months, they are about 50 feet long.

Blue Whales Are One of he Loudest Animals in the World

Blue Whale Blowing

NOAA / Wikimedia Commons / Public Domain

A blue whale's sound repertoire includes pulses, buzzes, and rasps. Their sounds are likely used for communication and navigation. They have very loud voices - their sounds can be over 180 decibels (louder than a jet engine) and at 15-40 Hz, are usually below our hearing range. Like humpback whales, male blue whales sing songs.

Blue Whales May Live Over 100 Years

Blue Whale Skull

Patricia Curcio / Wikimedia Commons / CC BY-SA 3.0

We don't know the true life span of blue whales, but the average life span is estimated around 80-90 years. A way to tell a whale's age is to look at growth layers in their earplug. The oldest whale estimated using this method was 110 years.

Blue Whales Were Hunted Nearly to Extinction

Whaling ship, 1947

Dutch National Archives / Wikimedia Commons / CC0 1.0

Blue whales don't have many natural predators, although they may be attacked by sharks and orcas. Their main enemy in the 1800-1900s was humans, who killed 29,410 blue whales from 1930-31 alone. It is estimated that there were more than 200,000 blue whales worldwide before whaling, and now there are about 5,000.

References and Further Reading

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Kennedy, Jennifer. "Blue Whale Facts." ThoughtCo, Apr. 5, 2023, Kennedy, Jennifer. (2023, April 5). Blue Whale Facts. Retrieved from Kennedy, Jennifer. "Blue Whale Facts." ThoughtCo. (accessed May 29, 2023).