Blue Whale Diet: Why Does This Marine Mammal Like Krill As Food?

Aashita Dhingra
Oct 23, 2023 By Aashita Dhingra
Originally Published on Nov 05, 2021
Blue Whale in Ocean.
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Age: 3-18
Read time: 5.8 Min

The blue whale (Balaenoptera musculus) is the largest animal to ever live in Earth's entire history.

Scientifically known as Balaenoptera musculus, they appear huge, but these giant marine mammals are harmless and non-predatory. You can call them 'gentle giants' because of their behavior and habits, as they cause no harm to humans.

Blue whales weigh tons and are many feet long! Blue whales (Balaenoptera musculus) are up to 110 ft (33.5 m) long and weigh up to 441,000 lb (200,000 kg). These marine mammals are the largest animals in the whole world.

They are usually solitary beings and tend to travel alone or in pairs, not pods like some other big fishes.

The blue whale is categorized as a mammal; they give birth to baby blue whales one at a time; these babies are called calves. After a 10-12 months gestation period, the mothers feed their young ones with their milk.

A baby blue whale doesn't consume krill but only milk during its first 6-18 months of growing up. What's even more fascinating is their life span! Blue whales live up to 90 years on average.

Blue whales have long and mottled (spotty) bluish-gray bodies; female blue whales are larger when compared to male ones. These gentle giants love eating krill, which are tiny shrimp-like crustaceans in the water; crustaceans are a diverse group of invertebrate animals.

These baleen whales engulf a vast school (group) of krill at a time. About 79,370 lb (36,000 kg) of krill is eaten by a blue whale every day.

Did you know that these giant whales are the loudest creatures on Earth? They are very well known for their vocalizations. The general frequency of their vocalizations ranges from 8-25 Hz, but this may vary depending on various factors. Blue whales are not only loud but also have excellent hearing abilities.

Blue whales have a blowhole for breathing purposes that works similarly to a nose. They exhale through the blowhole at the top of their body.

A massive cloud of pressurized air is thrown out as much as 30 ft (9 m) high in the air due to the force of exhalation. Blue whales tend to come up for air every 5-15 mins, but it is said that they can go for a longer duration without breathing.

Blue whales have earned the nickname of Sulphur Bottoms because the pale underside of their bodies has yellow coats of diatoms accumulated on them. A blue whale's age is measured by their earplugs because blue whales secrete earwax for most of their lives, leading to the formation of multiple layers in the plugs.

One layer forms every year, so the number of layers tells us the age.

After reading about the diet of the blue whale (Balaenoptera musculus), check blue whale facts and bear diet.

What is the main diet of blue whales?

Blue whales are giant, we all know that, but their favorite food (and main diet) is tiny crustacean creatures called krill (so they're obviously not vegetarians). Krill are approximately up to 2 in (5 cm) long.

They have unique habits of having their food; they engulf vast amounts of water and krill at a time, but only the krill enter their stomach, and the water is expelled out of their body.

A fully grown blue whale needs a considerable amount of energy per day; due to their high energy requirement, these whales are found in areas where krill are present.

When blue whales go hunting for food in the oceans, they tend to dive beneath the water, and with the help of the filter-feeding technique, they approach their prey. They come to a swarm of krill while their mouth is completely open, and then whales eat the prey along with tons of water.

Afterward, the water is pushed out from the mouth of baleen whales while ensuring that the krill is caught inside the mouth of a blue whale.

A Baby Humpback Whale Plays Near the Surface.

Why do blue whales only eat krill?

As stated above, whales love eating krill, but that's not the only food they have throughout their day (mostly other crustaceans).

You should know about krill because they are always in a group under the water (sometimes 30,000 individuals in one swarm). We all understand how giant a blue whale is; so, to satisfy their nutrient requirements and gain energy, they need to have their food in large quantities.

The easiest way for whales to satisfy themselves is by engulfing a whole swarm of krill at once along with water with their wide mouth; it's not a difficult task for them.

Another interesting fact about blue whales is that they lack sharp teeth; without sharp teeth, they cannot hunt and tear the flesh of their prey; so it's easier for them to swallow a massive swarm of their prey like krill.

When diving to catch prey for food, 11 minutes is the duration for which a blue whale will generally remain under the water. Usually, the baleen whale species will prey on krill along the surface of the water as krill are primarily found near the surface at night to avoid threats from predators (like the blue whale species).

Can a blue whale eat a shark?

The answer is no. As mentioned above, whales generally lack sharp teeth, and some of them have no teeth at all (like the baleen whale), so how can they tear their prey apart without a competent tool?

Blue whales cannot and do not eat sharks. For starters, most whales do not possess the type of teeth that can break through the flesh and bones of a shark; any aquatic animal would need strong and pointed teeth to hunt other animals and break them down into pieces small enough to swallow and digest.

The only types of whales that can possibly take down a shark are killer whales and sperm whales.

Blue whales are found in winter regions like the North Atlantic (northern hemisphere) and the Antarctic (southern hemisphere). The search is on, but sadly the current status of this animal in the Pacific or even in the Antarctic is endangered on this planet. If not conserved, this planet might see the extinction of this gentle animal.

Do blue whales eat humans?

If you're wondering whether blue whales eat humans, the answer is no.

Despite being the giants of the animal kingdom, blue whales do not eat humans and cannot do so even if they want to because of all the reasons mentioned above.

A blue whale's throat is very narrow, so it cannot swallow humans, and even if they somehow swallow humans, they cannot digest them because a blue whale's stomach isn't designed to eat something human-sized.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'Blue whale diet: why does this marine mammal like krill as food!'

then why not take a look at 'Chameleon species: curious kids facts on types of chameleon explained!' or 'Cheetah vs leopard: difference between the big wild cats revealed!'

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Written by Aashita Dhingra

Bachelors in Business Administration

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Aashita DhingraBachelors in Business Administration

Based in Lucknow, India, Aashita is a skilled content creator with experience crafting study guides for high school-aged kids. Her education includes a degree in Business Administration from St. Mary's Convent Inter College, which she leverages to bring a unique perspective to her work. Aashita's passion for writing and education is evident in her ability to craft engaging content.

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