Blue Whale Facts

The blue whale (scientifically referred to as balaenoptera musculus) is a large marine mammal that is part of the baleen whale (mysticeti) suborder and is the largest animal alive growing to lengths of up to 100 ft. long and weighing as much as 150 tons or more.

In addition to the blue whales massive size it is also one of the loudest animals in existence.

In fact a blue whales calls can be heard several miles away and far below the oceans surface.

Despite being the largest animal on earth the blue whales primary diet consists of krill, a small aquatic life form that resembles tiny shrimp.

Due to their large size these marine mammals are rarely ever attacked.

Other than humans that hunted blue whales during the whaling era the only known predator to the blue whale is a pack of hungry killer whale, however these attacks appear to be rare and rarely successful.

In cases where the blue whale is attacked the killer whales tend to go after a young defenseless whale rather than an adult blue whale.

Because the blue whale is able to travel through the ocean without worrying about being hunted themselves they are known as apex predators, which means they are predators that do not have any predators of their own.

Physical Characteristics and Appearance

Although the blue whale is referred to as having a deep blue color when they are at the surface of the water the blue whale actually appears to be a grayish blue.

When they dive back under the water the color of the water and the light from the sun make these marine mammals look a deeper blue than they really are.

As stated earlier when they are fully matured the blue whale can grow to be over 100 ft. long (average is around 70 – 80 ft.) and weigh more than 150 tons.

Even though they are massive animals their body is relatively slim and streamlined for speed and long distance travel allowing them to swim up to 25 miles per hour or more when the feel threatened (average speed is closer to 5 mph).

From an overhead position the blue whales oval shaped body resembles that of a submarine, but with with flippers and flukes.

The blue whale has a very small triangular dorsal fin as compared to the larger dorsal fin of many other whale species and the flippers which are used for steering are relatively short when compared to the rest of its body.

In fact the blue whales flippers only measure about 12% of the whales entire length.

Because the blue whale is a baleen whale it does not have any teeth, but instead relies on its baleen plates to capture its prey.

The baleen plates have bristles attached to them that act like a fence or net which allows the blue whale to capture its prey while also allowing water to freely move in and out of its mouth.

Diet and Hunting Methods

When it comes to their diet the blue whale is known to primarily consume krill, although other small ocean creatures such as copepods may also be ingested.

In order to maintain their steady diet the blue whale is almost always found in area’s with high concentrations of krill, such as in the Arctic ocean.

Because the blue whale does not have teeth they are unable to grab their prey or chew their food so they use a method known as “filter feeding” in order to obtain their prey.

Just as the name implies filter feeding involves filtering swarms or groups of krill from the water so that they can easily be consumed.

Filter feeding can be though of like using sifter that removes sand or water, but prevents larger objects from passing through the small holes.

The blue whale filter feeds works by opening its mouth while it swims towards a large swarm of krill in order to capture as many krill as possible in its mouth.

The blue whale then pushes the excess water out with its tongue while the krill stays trapped in the bristles.

Once all of the water is removed the whale swallows its prey whole.

Despite being such a huge animal the blue whale can only consume small prey due to the fact that its esophagus is too small to consume larger sources of food and it is unable to chew its food and break it down into smaller pieces.

In fact the blue whales esophagus is so small that it would not be able to swallow an adult human.

Habitat and Migration

In the past the blue whale was a very abundant species throughout the world however their overall populations have declined considerably since the whaling era, which was an extremely popular and lucrative business that unfortunately caused mass deaths among the various whale species between the 17th – 20th centuries.

The extent of the whale hunting was so severe in fact that it left the blue whale species nearly extinct.

Before the whaling era became extremely popular and lucrative it was estimated that between 200,000 and 300,000 blue whales existed in the world’s oceans, however since the whaling era ended estimates are closer to 5,000 – 12,000 whales with some researchers claiming possible higher numbers.

While this majestic species can still be seen living in many of the major oceans such as the Antarctic Ocean, Atlantic Ocean, Indian Ocean and the Pacific Ocean their populations have become scarce and largely fragmented because of the mass whaling that occurred in the past.

Today these marine mammals tend to be found in colder temperature waters where they can stock up on food in preparation for mating season, however they may also travel to warmer climates during certain times of the year.

These whales migrate towards colder polar waters during feeding season when large abundances of krill inhibit the cool waters and will travel to the warmer tropical waters during mating season where they can reproduce and give birth in steady waters.

During their migration trips the blue whale can travel thousands of miles from one location to the next.

While they migrate most whales will forgo eating food and live primarily off of blubber/body fat and stored calories.

The excessive amounts of food they consume during feeding season helps these marine mammals build up their supply of blubber which they’ll rely on for energy during their long trip.

Migration trips can last for up to 4 months depending on where they are traveling from or going to.

In order to minimize their energy expenditure and limit the amount of calories they use these marine mammals travel an average of 3 – 6 miles per hour during their migration, however when they feel threatened or agitated they  can reach speeds of over 30 miles per hour for short bursts.

Once the blue whale reaches its mating grounds it will spend the next several months socializing, mating and giving birth to live offspring before beginning its long journey back to its feeding grounds.

During their long journey the older, pregnant and sexually mature whales will typically travel first and furthest due to experience and excess body fat which allows them to deal with colder waters more effectively than younger whales.


This amazing species can often be found living in deep offshore waters near the upper and lower northern/southern hemispheres  in the Arctic and Antarctic regions during their feeding season (which takes places during the summer months).

During this time the blue whale can be seen eating large amounts of various prey to prepare for their long migration trip towards the equator and into places such as the Channel Islands, Farallon Islands and Monterrey Bay where they go to mate and give birth.

The summer is an ideal time for these marine mammals to stock up on food as their prey tends to migrate towards the northern/southern polar hemispheres during this time of year.

As stated earlier the blue whale can often be found in the upper and lower northern/southern hemispheres during feeding season, however when mating season comes around these large marine mammals begin their migration towards the warmer tropical regions of the world such as the Golf of Mexico and Costa Rica.

During mating season the blue whales will move to these warmer temperate waters to find a mating partner or bear offspring.

They will then mate and rest in their new-found home for several months before migrating back towards the Arctic and Antarctic waters they live in during their feeding season.

Although blue whales can be found living near the equator many of the blue whales will limit how close they come to the equator because they can become easily overheated due to their large size and thick layer of blubber.

The average gestation period for the blue whale is around 10 – 12 months, which provides these marine mammals with enough time to mate and bear offspring in the same tropical climate.

Social Structure and Communication

Blue whales are solitary animals often traveling alone or in small groups.

They communicate to one another by using loud low-pitched moans and whines which can be heard many miles away.

During mating periods adult blue whales may be heard performing mating calls which are often referred to as a mating song as they look for other whales to mate with.

These songs can often be heard over long distances and is even observable well below the surface of the water.

Although the exact reason for these songs is unknown it is believed that it may play a role in helping the whales find a mating partner, locate other pod members and even express sorrow when a pod member is sick or dies.

While these marine mammals tend to prefer smaller groups the blue whale can be found traveling in larger pods during periods of feeding, mating and migration.

Reproduction and Lifespan

Little is known about how blue whales reproduce.

The average gestation period for a female blue whale usually lasts 10 – 12 months once the female becomes impregnated.

At the end of the gestation term the female will give birth to a single offspring.

The baby blue whale can measure  in at 20 – 25 ft. long when born (1/4 – 1/3 the size of an adult blue whale).

For the first 6 – 9 months the newborn will be fed milk from its mother nipple.

The milk is full of fat and nutrients that will the child develop during its first months of life.

After the child stops being nursed by its mother it will begin to start consuming solid foods and hunting for its own prey.

Once the young whale matures around the ages of 5 – 10 years it can begin mating and reproducing on its own.

As with other baleen whale species when the blue whale reaches adult hood the female whales typically grow to be larger than their male counterparts.

While fertile the female blue whale may give birth every 2-3 years after giving birth to its previous child.

In terms of lifespan it is estimated that a blue whale may live for up to 90 years.


In the past during the whaling era the blue whale faced frequent threats from whalers and poachers looking to sell their oil so that it could be used to make various products.

Excessive hunting eventually led to huge declines in the blue whale population.

Eventually the act of commercial whaling begin outlawed making it illegal for companies and individuals to continue hunting them.

Today the blue whale is a protected species and anyone caught killing them could face fines and jail time.

While these marine mammals are relatively safe from human interaction they may still be hunted from time to time for their meat.

Aside from occasionally being hunted the blue whale may also face threats from pollution, collisions with boats and ships, global warming and incidents with fishing gear and other aquatic equipment.

As stated earlier these marine mammals do not have any known predators, however smaller less experienced blue whales may be occasionally attacked by a group of killer whales.

For more information about the whaling era read: The history of whaling.

10 Interesting blue whale facts

  1. Being able to grow to lengths of over 100 ft. long and weighing up to 180 tons the blue whale is the largest living animal in the world.
  2. Although the blue whale is called a “blue” whale it is actually closer to a grayish blue rather than a solid blue. It isn’t until the whale dives under the water that it appears to be a solid blue color.
  3. A baby blue whale can measure in at around 25 ft. long making it as big as a killer whale, which is the largest marine mammal in the dolphin species.
  4. A healthy adult blue whale can live for 70 – 90 years.
  5. The blue whale can eat as many as 40 million krill per day or around 8,000 lbs. daily in order to power its massive body.
  6. These marine mammals aren’t known to have any natural predators, except for occasional attacks on smaller (usually) baby whales by a pack of killer whales, however these attacks appear to be quite rare.
  7. When searching for food the blue whale can hold its breath for up to 35 minutes.
  8. Depending on where the research has been gathered it is estimated that as much as 95% – 99% of the entire blue whale population was killed during the whaling era.
  9. Due to significant hunting during the whaling era these marine mammals are now considered endangered and are listed as a protected species.
  10. The blue whale belongs to one of around 80 known species is Cetacea, which includes all species of whale, dolphin and porpoise.