40 Fascinating Blue Whale Facts (From Size & Diet to Conservation)

Oceans cover more than 70% of the planet, but that doesn’t adequately convey the amount of space available for aquatic animals to roam. Where land animals are limited by gravity, marine animals can go from coastal shallows to trenches the depths of which humans have barely begun to explore.

So it’s no surprise that the planet’s largest creatures, whales, are ocean-dwelling. In terms of the world’s largest animals, the competition isn’t even close.

The next largest animal of any species, the Whale Shark, is pint-sized compared to the five largest whale species. Clearly the only way to describe the marine mammal’s immensity—46 feet long, 15 tons— was to name it after whales.

African Elephants, the world’s largest living land animals, aren’t one-tenth the size of the largest whales. Even the dinosaurs weren’t as big as whales. Perhaps this explains why whale watching has become one of the most popular ecotourism activities.

If you’re going to discuss whales, it makes sense to start with the largest whale species of them all, the Blue Whale. Blue Whale size and weight stats are truly spectacular, making us humans seem tiny and utterly insignificant by comparison.

But there are plenty of other fascinating Blue Whale facts, including what they eat, where they live, why they’re endangered, how many remain, and what’s being done to save them. What follows is arguably the Internet’s most comprehensive array of Blue Whale information.

READ MORE: North Atlantic Right Whale Facts

General Blue Whale Facts

1. Blue Whales are one of around 80 species of Cetaceans, including other whales, dolphins, and porpoises. The term is derived from an ancient Greek word—këtos— that means “large fish,” but all members of this classification are mammals. Cetaceans are split into two parvorders: Odontoceti, or toothed whales, and Mysticeti, or baleen whales. The Blue Whale is a baleen whale.

2. Like other mammals, this species is warm-blooded and breathes via lungs. Mothers give birth to live baby Blue Whales, which they then nurse. 

3. The Blue Whale’s scientific name is Balaenoptera musculus, and there are actually three subspecies. Balaenoptera musculus musculus inhabits the North Atlantic and North Pacific. Balaenoptera musculus intermedia lives in the Southern Ocean, and Balaenoptera musculus brevicauda lives in the Indian Ocean.

4. Despite their common name, the Blue Whale is actually a more mottled blue-gray color when out of the water. However, underwater their skin appears to be true blue. Their pale bellies often take on a yellowish tinge, which results from the millions of microorganisms that live in their skin.

5. In addition to being the largest animal in the world, they’re amongst the longest living animals as well. The average Blue Whale lifespan is 80 to 90 years, but some live to 110 (Bowhead whales are the longest living mammal, at over 200 years). Strangely, a whale’s age is calculated by counting the layers of their waxy earplugs, á la tree rings!

READ MORE: Southern Resident Killer Whale Facts

Swimming Blue Whale Photo
Blue Whale by NOAA Fisheries/Lisa Conger [Public domain]

Blue Whale Size

6. Blue Whale size is staggering to consider: They can measure in the vicinity of 100 feet long (making them the longest animal in the world), and can weigh up to 200 tons. It’s difficult to conceive when we imagine something so big that sometimes moves at considerable speeds. 

7. The Blue Whale is the largest animal ever known to have lived on Earth. They are larger, longer, and heavier than any other animal, including all known species of dinosaurs.

8. More trivial tidbits about Blue Whale size: Its tongue weighs as much as an elephant and is roughly the same length. The Blue Whale weighs the equivalent of about 40 full-grown elephants, with a heart as heavy as a Volkswagen Beetle. It’s about as long as 2.5 school buses, measured bumper-to-bumper.

9. Blue Whale weight has been difficult to calculate due to the animal’s sheer mass. In order to weigh them, deceased whales have to be cut into manageable pieces (for scales that weigh trucks) and the sum total calculated. This results in fluid and blood loss that also has to be accounted for.

10. Baby Blue Whales enter the world already ranking among the largest animals, averaging 3 tons and 25 feet. They gain about 200 pounds every day for their first year of life, feeding on nothing but mother’s milk for the first few months.

11. The big Blue Whale also has the largest bone (its mandible), brain, and penis (more info on that below) of any animal on the planet.

12. Female Blue Whales are actually larger than the males.

13. Despite the Blue Whale’s size, it actually has a slender overall appearance compared to some other species of whales. From its broad head, its elongated body tapers into something that could easily be described as svelte.

14. At its widest point the Blue Whale measures about 25 feet across, accounting for the largest flukes (a.k.a. tail fins) of all.

15. As is the case with many baleen whales, Blue Whales have small dorsal fins (the top-of-body ones that sharks are famous for). A Blue Whale’s dorsal fin only measures an average of about 11 inches long. A male Orca’s dorsal fin, on the other hand, can grow up to six feet tall!

READ MORE: 60 Weird Animals Around the World

Blue Whale Habitat
Blue Whale by janeb13 via Pixabay

Blue Whale Habitat

16. Given their gargantuan size, you may be wondering where does the Blue Whale live. Interestingly, the answer is just about everywhere! Blue Whale habitat encompasses all of the planet’s oceans, though not necessarily at all times of the year.

17. Blue Whales generally like to spend their summers in cool polar waters. This is their feeding season, and their favorite food becomes more plentiful when colder environs warm up. The biggest Blue Whales are known to reside near Antarctica.

18. During the winter, Blue Whale migration patterns move them towards the equator. But they tend to avoid seas that are too warm, because they can easily overheat. This migration to warmer waters also helps with their reproduction cycle.

19. Blue Whale reproduction includes a 10- to 12-month gestation period. Mothers give birth every two to three years, often in the same habitat in which they were impregnated.

20. Blue Whale migration can occur in small groups (called pods), but they’re usually content to travel solo or in pairs. Even when they seem to be traveling alone, scientists who study Blue Whale behavior suggest they’re actually moving in pods miles apart, communicating via calls underwater.

21. Blue Whales usually swim at about five to 12 miles per hour. But when threatened (or inspired by other active whales), these behemoths can use those massive flukes to move at up to 30 miles per hour. 

22. The most concentrated Blue Whale habitats in winter are the waters off of Baja California,  Mexico and Pico Island, Portugal. During the summer, they frequent Quebec’s Gulf of St. Lawrence and Husavik, Iceland. Chile, the Maldives, and Sri Lanka are also prime spots for Blue Whale watching.

23. If you’re out looking for Blue Whales, keep in mind that they prefer to live in deep oceans and are rarely seen close to the shore. Weighing in at over 100,000 tons, how would they get there? These big, blue behemoths really need the space of the open seas.

READ MORE: Whales That Live in Antarctica

Blue Whale Flukes
“Blue Whale (Balaenoptera musculus)” by Gregory “Slobirdr” Smith is licensed under CC BY-SA 2.0

Blue Whale Diet

24. Though Blue Whales are known as gentle giants, they’re actually carnivores and apex predators. Simply put, they feed on other animals, and generally travel the oceans without worry of predators attacking them. This makes them vital to well-functioning marine ecosystems.

25. Like all baleen whales, Blue Whales don’t have any teeth. Instead, they have a system of fringed plates made of keratin (fingernail-like material) that filter out prey rather than tearing it apart. To feed, they take enormous gulps of water, then force the water out through the plates. This process ensnares small marine animals, which they then swallow whole.

26. The Blue Whale diet is mostly made up of Krill– shrimp-like creatures that are very small (about the two inches long). Nevertheless, using this gulp-and-filter technique, Blue Whales are known to consume 4 tons (approximately 40 million krill) a day during peak feeding season.

27. During migration (which can last up to four months), Blue Whales eat very little, instead living off the blubber they’ve acquired during peak feeding season. Despite their massive size, they only have a thin layer of blubber when compared to other whales. For example, Right Whales–which weigh a mere 100 tons and grow about 60 feet long– are much more blubbery.

28. As mentioned above, baby Blue Whales can gain over 200 pounds a day, averaging out to about 10 pounds an hour. This is accomplished by drinking up to 100 gallons of their mother’s milk (which is 35-50% fat) each day. They’re weaned at about six months, by which time they’re already over 50 feet long. After weaning, young whales start consuming solid foods and hunting their own prey.

READ MORE: Protecting Whales & Dolphins in Golfo Dulce, Costa Rica

Blue Whales Endangered
“Balaenoptera musculus” is licensed under CC BY 4.0

Why Are Blue Whales Endangered?

29. Given their massive size, you might wonder why Blue Whales are endangered according to the IUCN Red List. The only known Blue Whale predators (which are rarely successful) are pods of hungry Orca. And even these “Killer Whales” rarely prey on anything larger than a baby Blue Whale.

30. Prior to the 20th century, Blue Whale numbers were estimated in the hundreds of thousands. Approximately 95 to 99% of their global population was decimated by unchecked whale hunting. Their total number is currently estimated to be around 10,000, and slowly growing. 

31. Commercial whaling was banned in 1986 by the International Whaling Commission. But some countries have objected to the ban on cultural grounds, including Iceland and Norway currently as well as Russia and Japan historically. At least 2.8 million whales were killed in the 20th century alone. 

32. Nowadays, with the oceans steadily warming, climate change is becoming a serious Blue Whale threat. The warm waters are increasingly shrinking the Blue Whale’s habitat and distorting their annual migration patterns. The effect of climate change on Krill is even more problematic, as they need tons of Krill each day in order to have successful breeding cycles.

33. Other issues threatening Blue Whales include ship strikes and becoming ensnared in fishing nets. Lots of shipping routes cross their migratory routes, and irresponsible fishing practices from modern-day vessels and fishermen in the past have created problems by discarding their nets in the ocean.

READ MORE: 15 Harmful Traditions & Cultural Practices Tourists Should Avoid

Blue Whale Skeleton
“Balaenoptera musculus (blue whale) 3” by James St. John is licensed under CC BY 2.0

Blue Whale Conservation

34. Blue Whale conservation efforts have been both numerous and largely successful. Most of them have centered around stopping whaling in general, with only a handful of countries remaining among the holdouts. Luckily, Blue Whales are not among the list of cetaceans most likely to be hunted.

35. The International Whale Commission created whaling regulations in 1946 and enacted an all-out ban in 1986, referred to as the commercial whaling moratorium. Blue Whale protection has also been extended under the Species at Risk Act (Canada) and Endangered Species Act (United States), among other initiatives across the globe.

36. Blue Whale protection also comes from a bevy of other wildlife conservation organizations, such as Whale and Dolphin Conservation, Save the Whales, and Sea Shepherd Conservation Society. These NGOs make efforts to prevent whaling, safeguard Blue Whale habitats, reconfigure problematic  shipping routes, and keep the ocean clean. 

READ MORE: Jean-Michel Cousteau on the Future of Marine Conservation

Facts about Blue Whales
Blue Whale exhale in Sri Lanka by Christopher Michel via flickr & CC & 2.0

Other Blue Whale Facts

37. Blue Whales are one of the loudest animals in the world. They emit pulses, groans, and moans that can be heard hundreds of miles away. These songs can be used to communicate, navigate, and for mating purposes. At 188 decibels, some of their calls are louder than a jet engine. But, at 15-40 Hz, they are often below our human hearing range.

38. As mammals, Blue Whales require lungs and air to breathe. They inhale and exhale via their blowhole, which is located on top of their massive heads. For deep dives, they can take in enough oxygen to last 90 minutes underwater, but typical dives only last half an hour. When they exhale, the spray that erupts into the air is from water that congregates atop the blowhole while submerged.

39. The Blue Whale’s mouth is extraordinary! Their throats have expandable pleats, and their mouths can open so wide that another whale could actually swim into them. Scientists studying this phenomenon calculated that the Blue Whale’s mouth captured enough food during a truncated 11-minute dive to provide 100 times the energy used to make the dive in the first place. 

40. At the risk of being grotesque, the Blue Whale’s penis is dumbfounding, reaching 8 to 10 feet long. It weighs several hundred pounds, but is hidden inside a genital slit during normal daily activities. Each time they have intercourse, a Blue Whale can ejaculate 30-40 pints of semen, which increases their chances of reproduction and flushes out the sperm of competing males. 

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Blue Whale Blowhole
Blue Whale Blowhole Photo by NOAA

FAQs About Blue Whales


How many Blue Whales are left in the world?

The numbers are somewhat up for debate, but most NGOs seem to settle somewhere close to 10,000. Pessimistic groups might estimate a population somewhere in the 5,000 to 10,000 range, whereas more optimistic collectives might stretch their Blue Whale numbers up to 25,000.

Despite being by far the largest animals on earth, Blue Whales are notoriously elusive. So it’s very difficult to get an accurate read on theit global population.

That being said, what we do know for sure is that over 350,000 Blue Whales were killed by hunters between 1900 and 1960, prior to the International Whaling Commission putting regulations on the practice. Since then, these gentle giants have rarely died by the harpoon.

What do Blue Whales eat? 

For the most part, Blue Whales eat Krill. Krill are tiny crustaceans that resemble shrimp and are about the size of a human’s pinky finger.

During feeding season, they can consume about 4 tons of Krill a day. They do also consume other sea creatures, including a few other crustaceans, as bycatch to the Krill.

What is the difference between a male and female Blue Whale?

Female Blue Whales are actually the larger of the species, averaging about 32 feet (or 10 meters) longer than males and weighing around 30,000 tons more.

Obviously, they have different sexual organs, but they are otherwise very similar in color, appearance, habitat, and migration.

Female Blue Whales are called cows, while males are called bulls. Baby Blue Whales are called calves.

Are Blue Whales the biggest animal ever?

Blue Whales are the biggest animal currently in existence, including being the longest, largest, and heaviest. They are also the largest known animal to have ever existed. The Finback Whale is nearly as long as its Blue cousin, measuring close to 90 feet long. But it weighs significantly less.

The Right Whale, the planet’s second heaviest animal, can get up to 100 tons, which is about half what the largest Blue Whale can weigh. The largest African Elephant– the world’s biggest living land animal– is about a quarter the length of a Blue Whale, and just one-fortieth the weight.

Due to space and buoyancy, sea-going animals like whales can grow to be much larger than land animals, which need skeletons that can support their bodies.

Are Blue Whales bigger than dinosaurs?

Blue Whales are bigger than dinosaurs, particularly those puny T-Rexes and other apex carnivores. A few members of the sauropods– herbivorous dinosaurs with long necks– are projected to have possibly been longer than Blue Whales.

Supersaurus and Argentinoasaurus are believed to have been over 100 feet long. However, their dimension projections are based on only a few bones, with nothing even close to an entire skeleton.

Nearly half of their length was in their necks, so Blue Whales are believed to easily weigh twice as much (or more) as these dinosaurs did. In other words, not only are Blue Whales bigger, but they are MUCH larger than even the biggest, fabled dinosaur. —Jonathon Engels

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