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Blue Whales

















What is taxonomy?

Blue whales are the largest baleen whale species--in fact they are the largest animal in the world.  Blue whales can grow to be about 100 feet (30.5 meters) in length and may weigh around 160 tons. They are mottled bluish gray, with broad flat heads and a small dorsal fin located in the last forth of the body.  Newborn blue whales are about 23 feet (7 meters) long and roughly 30 tons and can add 200 pounds a day! 

Interesting Facts:

  • Blue whales are the largest animals to have ever lived on Earth with some individuals reaching lengths of nearly 100 feet (30.5 meters).    Yes, they are even larger than dinosaurs!
  • A blue whale heart is the size of a Volkswagen Beetle and pumps 10 tons of blood through the massive blue whale body. A blue whale aorta (the main blood vessel) alone is large enough for a human to crawl through.
  • Blue whale blows, also called spouts, consist of air and water and rise about 30 feet (9.1 meters) high.

What should I know about blue whales?

Where do blue whales live?

Blue whales live in all oceans of the world.   They feed in high latitudes and migrate to the tropics to breed and give birth.

How many blue whales are there?

The worldwide blue whale population is unknown however, blue whales are considered endangered according to the U.S. Endangered Species Act.  Blue whales were hunted extensively for their large quantities of baleen, blubber, and meat.  Although blue whales are protected, their populations show few signs of recovery.  You can read more about blue whale stocks in the NMFS Alaska and Atlantic stock assessment reports..

How can I identify a blue whale?

They are huge! Blue whales in the Antarctic reportedly reached lengths of 110 feet (33.5 meters), however most probably grow to 80-90 feet (24.4-27.4 meters) long.  Female blue whales are generally larger than males, and northern hemisphere blue whales are generally smaller than those in the southern hemisphere.  Blue whales are light bluish gray on their dorsal side and mottled gray whitish on their bellies.  Some have yellowish bellies.

How well can a blue whale see or hear?

It is hard to know the answer to this question since blue whales are so big and live in the open ocean.   It is thought that baleen whales (including blue whales) probably have excellent hearing, especially at low frequencies, which is valuable in the dark ocean environment where vision is less useful. 

What do blue whales eat?

Blue whales filter their food through their baleen plates. Blue whales eat krill (euphausiids) and copepods.  A blue whale can eat up to 8,000 lbs. of krill during its peak consumption period. It is estimated to take 2,200 lbs. of food to fill a blue whale's stomach.

How do blue whales have their young?

Blue whales begin mating between 5-10 years of age.   Females are pregnant for about 11 months and females get pregnant approximately every two to four years. Calves can gain 200 lbs. each day while nursing.  Mother and calf form a very close bond, with the baby often swimming close to its mother.

How long do blue whales live? How do they die?

Because of an absence of teeth (which can be used to estimate age in other mammals), it is difficult to tell how old blue whales are when they die.  It is believed they live past 50 years old.

Blue whales die of natural causes and are sometimes preyed upon by packs of killer whales.   Humans commercially hunted blue whales for oil, meat, and apparel materials (for corset stays, umbrella ribs, buggy whips etc.) until early this century.  Today blue whale hunting is illegal in the United States.  Blue whales may also be harmed by pollution, ship strikes, or entanglement in fishing gear.

Where can I find more information about blue whales?

Books and the world wide web are excellent places to learn more about marine mammals. 


  • Leatherwood, Stephen. Reeves, Randall R. Foster, Larry.   The Sierra Handbook of Whales and Dolphins.  Sierra Club, San Francisco, CA.  1983.
  • Leatherwood, Stephen.  Reeves, Randall R. Perrin, William F.   Evans, William E.  Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic waters; A Guide to their Identification.  Dover Publications, Inc., New York, NY.  1988.
  • Wynne, Kate. Folkens, Pieter. Guide to Marine Mammals of Alaska.  Alaska Sea Grant Program.  University of Alaska Fairbanks, Fairbanks, AK.  1992. 

World Wide Web

There are many more sources to learn about cetaceans.   Check with MML's online library or your local librarian for her or his recommendations.

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This portion of the MML website is intended for a student audience and their educators.
Information within the education website should not be cited in scientific journals or publications.

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