The blue whale (scientifically referred to as Balaenoptera musculus) is a large marine mammal.
These marine mammals are part of the baleen whale (Mysticeti) suborder.
They are also the most prominent animal, growing up to 100 ft. long and weighing 150 tons or more.
In addition to the blue whale’s massive size, it is one of the loudest animals.
People and other animals can hear a blue whale call several miles away and far below the ocean’s surface.
Despite being the largest animal on earth, the blue whale’s primary diet consists of krill, a small aquatic life that resembles tiny shrimp.
The blue whale’s large size means they rarely ever get attacked.
Other than humans that hunted blue whales during the whaling era, the only known predator is killer whales.
However, these attacks appear to be rare and seldom successful.
Killer whales often go after a young defenseless whale rather than adults when attacking them.
Blue whales typically travel through the ocean without worrying about other animals or humans attacking them.
As a result, blue whales are apex predators, which means they do not have any primary predators.
Physical Appearance and Anatomical Characteristics
Blue whales are known for their deep blue color.
However, when they are at the water’s surface, the blue whale appears to be a grayish blue.
When they dive back under the water, the water’s color and the sun’s light make these marine mammals look a deeper blue than they are.
As stated earlier, when fully matured, an enormous blue whale grows over 100 ft. long, most measuring about 70 – 80 ft.
In rare circumstances, some giant blue whales weigh over 150 tons.
Even though they are massive animals, their body is relatively slim and streamlined for speed and long-distance travel.
It allows them to swim up to 25 miles per hour or more when they feel threatened (average speed is closer to 5 mph).
From an overhead position, the blue whale’s oval-shaped body resembles that of a submarine but with flippers and flukes.
The blue whale has a tiny triangular dorsal fin compared to the larger dorsal fin of many other whale species.
They also have flippers for steering that are relatively short compared to the rest of their body.
The blue whale’s flippers only measure about 12% of the whale’s entire length.
Because the blue whale is a baleen whale, it has no teeth.
Instead, it relies on its baleen plates to capture its prey.
The baleen plates have bristles that act like a fence or net.
It allows the blue whale to capture its prey while allowing water to move freely in and out of its mouth.
Diet and Hunting Methods
When it comes to diet, blue whales primarily consume krill.
Nevertheless, blue whales also consume other small ocean creatures, like copepods, which they ingest while eating krill.
Blue whales are primarily found in areas with high concentrations of krill, like the Arctic Ocean, to maintain their diet.
Because blue whale does not have teeth, they cannot grab their prey or chew their food.
As a result, they use a method known as “filter-feeding” to obtain their target.
Filter-feeding involves sifting swarms or groups of krill from the water using their bristles.
It enables the blue whale to consume small prey while filtering out larger objects they cannot easily swallow.
Essentially, filter-feeding 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 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.
It swallows its prey after removing the excess water.
As previously mentioned, this marine mammal can only consume small prey despite being such a vast animal.
The blue whale’s esophagus is too tiny to consume more significant food sources.
In addition, it cannot chew its food and break it down into smaller pieces making it problematic to consume large prey.
The blue whale’s esophagus is so tiny that it cannot swallow an adult human.
Habitat and Migration
In the past, the blue whale was a very abundant species worldwide.
However, their overall populations have declined considerably since the whaling era.
The whaling era was a lucrative business that caused mass deaths among various whale species between the 17th – 20th centuries.
The whale hunting was so severe that it left the blue whale species nearly extinct.
Before whaling became popular and lucrative, between 200,000 and 300,000 blue whales existed in the world’s oceans.
However, estimates are closer to 5,000 – 12,000 whales since the whaling era ended.
Some whale researchers claim the number of deaths is likely much higher.
This majestic species lives in multiple oceans, including the Antarctic Ocean, Atlantic Ocean, Indian Ocean, and Pacific Ocean.
However, their populations have become scarce and fragmented because of the mass whaling that occurred in the past.
Current Data
Today blue whales live in cold waters to stock up on food in preparation for mating season.
Nevertheless, they may also travel to warmer climates during certain times.
Blue whales migrate towards colder polar waters during feeding season when large krill abundances inhibit the calm waters.
Then, they travel to the warmer tropical waters during the mating season to 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 forgo eating and live primarily off blubber/body fat and stored calories.
The excessive food consumed during the feeding season helps these marine mammals build up their fat supply.
Their additional fat enables them to rely on it for energy during their long trip.
Migration trips can last up to 4 months, depending on where they are traveling or going.
To minimize their energy expenditure and limit their calories, 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.
Blue Whale Locations
This fantastic species can often live in deep offshore waters near the upper and lower northern/southern hemispheres.
It includes locations in the Arctic and Antarctic regions during their feeding season in the summer.
During this time, the blue whale eats large amounts of prey to prepare for its long migration toward the equator.
It includes places such as the Channel Islands, Farallon Islands, and Monterrey Bay, where they go to mate and give birth.
The summer is ideal for these marine mammals to stock up on food for their journey.
Their prey tends to migrate toward the northern/southern polar hemispheres.
As stated, the blue whale lives in the upper and lower northern/southern hemispheres during feeding season.
However, when mating season comes around, these large marine mammals begin migrating toward the warmer tropical regions of the world.
It includes locations such as the Gulf of Mexico and Costa Rica.
The blue whales will move to these warmer temperate waters during mating season 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 travel near the equator, many will limit how close they come to the equator.
They can become easily overheated due to their large size and the thick layer of fat they’ve stored.
The average gestation period for the blue whale is around 10 – 12 months.
It provides these marine mammals 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 rough, loud, low-pitched moans and whines, which animals and humans can hear many miles away.
Adult blue whales may perform mating calls during mating periods.
Scientists and researchers call these mating songs because blue whales use them to look for mating partners.
These songs can often be heard over long distances and are even observable below the water’s surface.
The exact reason for these songs is unknown.
However, scientists and researchers believe the song plays a significant role in helping the whales find a mating partner.
They may also use these songs to locate other pod members and even express sorrow when a pod member is sick or dies.
In most cases, blue whales prefer smaller groups.
However, they can travel in larger pods during feeding, mating, and migration.
Mating, Reproduction and Lifespan
Unfortunately, there isn’t a lot of information 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 gestation, the female will give birth to a single offspring.
The baby blue whale can measure 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’s nipple.
The milk is full of fat and nutrients the child will develop during its first months.
After the mother stops nursing the child, it begins consuming solid foods and hunting for prey.
Once the young whale matures around 5 – 10 years, it can begin mating and reproducing.
As with other baleen whale species, when the blue whale reaches adulthood, the female whales typically grow more significantly than their male counterparts.
While fertile, the female blue whale may give birth every 2-3 years after giving birth to its previous child.
Some blue whales live up to 90 years with the proper diet, climate, and lifestyle.
Threats and Predators
In the past, during the whaling era, the blue whale faced frequent threats from whalers and poachers.
These hunters typically poached blue whales to sell their oil to make various products.
Excessive hunting eventually led to considerable declines in the blue whale population.
Eventually, commercial whaling began to be outlawed, making it illegal for companies and people to continue hunting them.
Today, the blue whale is a protected species. Anyone caught killing them could face fines and jail time.
These marine mammals are relatively safe from human interaction.
Nevertheless, some poachers still hunt blue whales from time to time for their meat.
Aside from occasionally being hunted, the blue whale may also face threats from other sources and hazards.
It includes pollution, collisions with boats and ships, global warming, fishing gear, and other aquatic equipment incidents.
As stated earlier, these marine mammals do not have any known primary predators.
However, a smaller, less experienced group of killer whales may occasionally attack blue whales.
For more information about the whaling era, read The history of whaling.
10 Interesting Blue Whale Facts
- 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.
- Although the blue whale is called a “blue” whale, it is closer to a grayish blue than a solid blue. It isn’t until the whale dives under the water that it appears solid blue.
- A baby blue whale can measure around 25 ft. long, making it as big as a killer whale, the largest marine mammal in the dolphin species.
- A healthy adult blue whale can live for 70 – 90 years.
- The blue whale can eat as many as 40 million krill daily or around 8,000 lbs. daily to power its massive body.
- 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.
- The blue whale can hold its breath for 35 minutes when searching for food.
- Estimates claim that as much as 95% – 99% of the blue whale population died during the whaling era.
- Due to significant hunting during the whaling era, these marine mammals are now considered endangered and are listed as protected species.
- The blue whale belongs to one of around 80 known species, Cetacea, which includes all species of whale, dolphin, and porpoise.