All About Blue Whales: The Big Ocean Wardens

Leave a comment / / Updated on: 11th November 2023

NameBlue whaleDietCarnivorous
Scientific nameBalaenoptera musculusWeight100 to 199 metric tons (110 to 220 short tons)
Pronunciationbloo weilLength21 to 33 meters (68.9 to 108.3 feet)
ClassificationMammalia, Artiodactyla, & CetaceaLocationWorldwide

The Blue Whale

Blue Whale in the Indian Ocean
Blue Whale in the Indian Ocean / eco2drew via iStock

Known for their large size and unique vocalizations produced at very low frequencies, blue whales are the ocean’s most renowned inhabitants!

Few people have seen blue whales in all their splendor, but they’re still the subject of discussions by many wildlife enthusiasts and scientists. 

Their solitary and elusive lifestyle only adds to the fascination!

Having lived for more than a million years, blue whales are an essential part of the oceanic ecosystem. 

Unfortunately, their population number has significantly decreased over the years, which is why we’ve decided to share some breathtaking facts about them! 

Raising awareness is, after all, an excellent way to contribute to saving our planet!

Gage Beasley's In-Demand Plush Toys
Gage Beasley’s In-Demand Plush Toys

Taxonomy and Classification

A Blue Whale showing the blowhole
A Blue Whale showing the blowhole / NOAA via Wikipedia Public Domain

The blue whale is scientifically called Balaenoptera musculus and is part of the Balaenoptera genus, alongside other whales like the common minke whale or fin whale. 

Together, they are in the Balaenopteridae family of rorquals, which is classified under the Cetacea order.

Besides the living species, the blue whale is related to prehistoric ones, some of which date back to the Neogene, meaning they lived 20 million years ago! 

Blue whales themselves date back to the Early Pleistocene, when they roamed through our planet’s oceans and, over the years, underwent multiple divergences that gave rise to several subspecies.

Scientists recognize four blue whale subspecies:

  • The northern subspecies (B. m. musculus) are, in turn, divided into three populations – the North Atlantic, Eastern North Pacific, and Central/Western Pacific populations.
  • The pygmy blue whale (B. m. brecivauda) is, in turn, divided into three populations – the Madagascar, Australia/Indonesia, and Eastern Australia/New Zealand populations.
  • The northern Indian Ocean subspecies (B. m. indica)
  • The Antarctic subspecies (B. m. intermedia)

Blue whales are known to interbreed with fin whales, also known as common rorquals or razorback whales, although only a few individuals have been documented. 

Physical Characteristics

Size comparison of selected giant sauropod dinosaurs
Size comparison of selected giant sauropod dinosaurs / KoprX via Wikipedia CC BY-SA 4.0

You must have heard about sauropods if you’re a wildlife enthusiast, right?

If so, you probably know how large they were. 

One would even say they were truly the world’s largest creatures, considering that some may have weighed as much as 110–130 metric tons (121–143.3 short tons).

Well, what if we told you that blue whales are larger? Or that blue whales are, in fact, the largest creatures that our planet has ever known?

Although blue whales are often named the world’s largest creatures ever, the truth is that this may not be entirely accurate because it depends on what we take into consideration.

The weight or the length?

Besides this, not all blue whale populations grow so large.

An adult blue whale
An adult blue whale / NOAA Photo Library via Wikipedia Public Domain

For example, pygmy blue whales weigh only 83.5–99 metric tons (92–109 short tons), whereas the northern populations weigh 100-112 metric tons (110–123.5 short tons) on average!

Still, the largest blue whale ever documented weighed between 173–199 metric tons (190.7–220 short tons)! Just imagine what a giant it was!

What about the length? It’s just as remarkable! Some specialists believe that the maximum size blue whales can attain is 30.5 meters (100 feet), although some have reported lengths that go beyond that, reaching 33 meters (108.3 feet).

Besides their noticeable gigantism, blue whales have quite an interesting body: they are slender and have U-shaped heads, a sickle-shaped dorsal fin, and a sturdy whale-typical fluke.

They also have between baleen plates lined on their upper jaws, which means that they open their mouths to take water, then push it out while the krill remain inside the mouth. 

Blue whales also have two large blowholes that allow them to breathe.

The skin on a blue whale’s underbelly is light to yellowish, while the rest of the body is grayish, which appears almost blue if the whale is underwater.

Habitat and Distribution

Blue whales are found almost worldwide, except for the Bering, the Okhotsk, and the Mediterranean seas, as well as the Arctic Ocean. 

Their populations (subspecies) are grouped depending on their geographic location.

Blue whales are typically migratory and follow seasonal routes from and to breeding and wintering grounds. 

Nonetheless, it is believed that these movements are primarily prompted by food availability.

For example, the populations wintering in Mexico and Central America spend their summer off the western U.S. coast. 

Other groups, such as those living in the northern Indian Ocean, are year-round residents.

These giant aquatic mammals typically swim and feed at depths of approximately 100 meters (330 feet), although they can dive to incredible depths of 506 meters (1,660 feet)!

This record was set by a pygmy blue whale!

Behavior and Social Structure

A rare sighting of a blue whale mother and baby in the Pacific Ocean
A rare sighting of a blue whale mother and baby in the Pacific Ocean / PeakMystique via iStock

Although typically solitary, blue whales are sometimes seen in large groups, especially if they’re starting their migratory routes, during which they travel at a speed of 5 km/h (3.1 mph). 

However, if necessary, they can reach 30 kmh (18.6 mph).

Besides traveling together, blue whales also communicate with each other, particularly while feeding or during the breeding season, when males compete for females.

The curious thing is that those vocalizations are emitted at very low frequencies. 

Some of them resemble a purring cat sound! It is believed that, if circumstances are favorable, their vocalizations could be heard by other whales swimming 1,600 kilometers (1,000 miles) away!

Diet and Feeding

Blue whale underwater chasing school of fish side
Blue whale underwater chasing school of fish side / bbevren via iStock

Blue whales feed primarily on krill. They rely on their ability to swim fast while feeding. 

Blue whales have to use their best swimming speed when approaching krill to gather as much water as possible when they open their mouths.

Then, blue whales rely on their baleen plates to remove the water, while at the same time keeping the krill inside their mouths and delighting in their delicious meals, which usually include between 1,120 and 1,400 kilograms (2,470–3,086 pounds) of krill.

Unfortunately, considering their size, blue whales cannot feed as many times as they want because that would require too much energy. 

Therefore, these giant creatures evolved to adapt various foraging strategies to preserve energy, including the engulfing of large volumes of prey.

Additionally, they’ve learned how to perform diverse feeding maneuvers that imply reorienting their bodies to engulf the desired krill group. 

Studies have shown that these rolling behaviors improve their foraging efficiency.

Reproduction and Life Cycle

A blue whale calf with its mother
A blue whale calf with its mother / Andreas Tille via Wikipedia CC BY-SA 4.0

When the mating season comes (fall-winter), males and females engage in something called courtship behavior. 

Well, males actually start chasing females around for weeks until they mate.

Sometimes another male joins him, and the two start competing for the female. 

It is believed that, for the female to choose, the males must race along the water surface.

Supposedly, this informs the future mom of her potential mate’s health.

Additionally, males may rely on their vocalizations to communicate with other male competitors. 

Once the female chooses the mate, we’re left in the dark, as the way blue whales actually mate is poorly documented.

Blue Whale spotted near Palos Verdes, California
Blue Whale spotted near Palos Verdes, California / Lpettet via Getty Images

Once fertilization occurs, females undergo a gestation period of 10–12 months, during which they must feed well. 

The calves are born quite large, weighing 2–3 metric tons (2.2–3.3 short tons) and measuring 6–7 meters (20–23 feet) long. 

After birth, the mother feeds her calves with milk, which amounts to approximately 220 kilograms (485 pounds) of milk a day.

The calves are weaned 6–8 months after birth or when they reach 16 meters (53 feet) long.

Sexual maturity is attained at 8–10 years of age.

Blue whales are known to live between 80 and 90 years, although some can reach extraordinary lifespans of 110 years!

Ecological Role and Interactions

A Blue Whale underwater
A Blue Whale underwater / eco2drew via iStock

The blue whale is considered a keystone species in its habitat.

This means that it has a huge effect on the ocean’s health, community structure, and balance. 

If blue whales didn’t exist, our planet’s oceans would be much different than they are today.

Now you’re probably wondering how exactly blue whales contribute to the ocean’s ecosystem, right? 

If anything, they’re damaging the krill population, considering the amount of food they need to survive! 

Well, the truth is that blue whales sustain krill reproduction through their poop!

Blue whale feces are rich in iron and nitrogen, which are essential for phytoplankton to thrive.

A young orca chases a chinook salmon in the Salish Sea
A young orca chases a chinook salmon in the Salish Sea / Oregon State University via Wikipedia CC BY-SA 2.0

In turn, phytoplankton sustain the krill population, as that’s their main food source.

In short, blue whales donate their poop to the ocean.

The phytoplankton takes advantage of its nutrients to thrive and then serve as food for krill, increasing their numbers. 

Blue whales feed on the mentioned krill, upon which they poop, releasing the required nutrients, and the whole cycle starts again.

Phytoplankton aren’t important only to the krill population.

They’re also experts at removing carbon dioxide from the atmosphere!

Blue whales don’t interact only with their prey.

Sometimes orcas take their chance to hunt the giant blue whales, although they rarely manage to kill and feed on them. 

Pod of Orcas in Frederick Sound
Pod of Orcas in Frederick Sound / Ron Sanford via Getty Images

Scientists aren’t even sure of the rate of fatal attacks, although they assume that orcas typically target calves.

Besides the interactions mentioned above, blue whales serve as hosts for external parasites like barnacles, white lice, and copepods. 

They can also host internal parasites like trematodes, tapeworms, and thorny-headed worms.

Conservation Status and Threats

Unfortunately, the IUCN Red List assessed the blue whale species as Endangered. 

At the moment, there are only 5,000–15,000 mature individuals.

A century ago, the blue whale population consisted of at least 140,000 mature individuals. 

A Blue Whale being filmed by a diver
A Blue Whale being filmed by a diver / Gerard Soury via Getty Images

However, thanks to conservation efforts, which include naming the species as protected, blue whale numbers are now increasing.

Blue whales have been historically threatened by direct exploitation. 

At the beginning of the 20th century, between 350,000 and 360,000 Antarctic blue whales were caught, while the North Atlantic population suffered a loss of 11,000 individuals. 

Since 1966, however, the species has been legally protected.

This significantly reduced the whaling rate.

Nonetheless, their numbers were still decreasing.

Considering their size, many blue whales are at risk of being hit by ships and suffering serious injuries that prevent them from swimming. 

 Most ship strikes occur off the U.S. West Coast and in Sri Lankan waters.

This problem can be solved by establishing better predictive models of blue whale distribution and migration, as well as reducing vessel speed and changing shipping lanes.

An aerial view of blue whale in blue ocean
An aerial view of blue whale in blue ocean / Carl Finkbeiner via Getty Images

Although scientists confirmed that blue whales were contaminated with various pesticides and other pollutants, they couldn’t confirm how much these chemicals affected their well-being.

On the other hand, man-made noises, like commercial ship noises and seismic surveys, can greatly affect the behavior of the blue whales that feed deeper in the water. 

Unique Adaptations and Survival Strategies

Did you know that whales weren’t always aquatic?

One of the oldest cetaceans was Pakicetus, which lived near the shore and had fully functional legs.

Approximately 49 million years ago, cetaceans started transitioning from terrestrial to aquatic animals, which implied developing unique adaptations that would allow them to survive in the water.

Blue whales are not an exception, as they also retain some adaptations that allow them to thrive in our planet’s oceans.

Here are some:

  • Streamlined bodies that allow smooth swimming
  • Elongated flippers
  • A strong fluke that moves up and down in powerful strokes, thus facilitating swimming and serving as protection against orcas
  • Blowholes that allow underwater breathing
  • Well-developed hearing
  • A blubber that acts as a thermal insulator
  • Highly efficient lungs that exchange 80–90% of oxygen
  • A unique sleeping method, which implies that half of their brain stays awake
Blue Whale
Blue Whale showing its tail fin / Gerard Soury via Getty Images

Cultural Significance and Human Interactions

Native American cultures portray blue whales as guardians of the ocean. 

They are symbols of wisdom, good luck, and spiritual awareness.

Besides this, people often regard them as symbols of love, emotional health, and exploration of inner experiences.

Due to their solitary nature and elusiveness, blue whales are often associated with solitude and nostalgia.

The guardians of the ocean are illustrated and described in multiple books about wildlife, as well as children’s stories, among which one that stands out is Big Blue Whale: Read and Wonder written by Nicola Davies and illustrated by Nick Maland.

Blue whales never had any negative interactions with humans, as no attacks on humans are known. 

On the contrary, in Iceland, for example, they are known as the big protectors of the fishing boats.

Two blue whales swimming side by side at Channel Islands National Marine Sanctuary
Two blue whales swimming side by side at Channel Islands National Marine Sanctuary / National Marine Sanctuaries via Wikimedia Commons Public Domain

They can be quite friendly toward people, although they choose to avoid them if possible.

Future Prospects and Research

Although blue whales are quite well-studied and understood, ongoing research is still of utmost importance.

Many aspects of their lifestyle remain unknown because of their size.

Scientists are particularly fascinated by blue whale vocalizations and focus their studies on outlining the changes in their tonal frequency. 

Other researchers focus on studying their distribution, identification, population structures, ecological roles, and the effect of noises and ships on their well-being.

All these studies are essential to protecting the blue whale population.


Blue whales, scientifically called Balaenoptera musculus, are the world’s largest oceanic creatures. 

These aquatic giants grow up to 33 meters (108.3 feet) long and weigh as much as 199 metric tons (220 short tons)!

Since they are baleen whales, these aquatic mammals are equipped with multiple plates that allow them to filter the krill out of the water they engulf while feeding.

Despite their common name, blue whales aren’t blue.

They are rather grayish on top and lighter on the undersides. 

However, when submerged, their skin looks blue on top and yellow on the underbelly.

Their streamlined bodies are equipped with elongated flippers, a sickle-shaped dorsal fin, and a fluke that moves up and down, unlike fish tails, which move from side to side.

Unluckily, these gorgeous, remarkable creatures are on the brink of extinction. 

Although the blue whale population numbers are increasing, they are still at a high risk of being hit by ships, and their well-being and behavior are affected by various underwater noises and possibly pollutants.

Therefore, it is of the essence to support any conservation efforts if possible and raise awareness about the threats blue whales face.


How rare is it to see a blue whale?

Blue whales are quite rare sightings.

It has been suggested that only 1% of our global population was lucky enough to spot a blue whale.

What’s bigger than a blue whale?

The blue whale is now widely regarded as the world’s largest animal.

Some sources mention that the extinct Perucetus colossus was larger.

It may have been, but only in terms of weight, as this extinct whale did not grow longer than 20 meters (65.6 feet).

Additionally, some dinosaurs may have been longer than blue whales but weighed less.

In the end, it would be impossible to say whether the blue whale is indeed the largest animal that has ever existed because this depends on multiple factors.

On the other hand, it is undoubtedly the world’s largest living animal!


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