What Is the Largest Animal in the World? A Magnificent Creature

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The blue whale is the largest animal in the world, far larger than any dinosaur.

A mature blue whale can reach a length of 30 meters and a weight of over 180,000 kg, which is equivalent to 40 elephants, 30 Tyrannosaurus Rex, or 2,670 average-sized persons. However, this behemoth among giants was once much tiny.

The blue whale (Balaenoptera musculus), like all whales, descended from a four-legged land animal about 48 million years ago. Pakicetus, its extinct progenitor, was merely 1.8 meters long, nowhere near its descendant, now the largest animal in the world. It ate in streams, and some of its offspring developed aquatic adaptations. This ultimately resulted in the 4.5-meter-long Dorudon (“Spear-Tooth”), an entirely aquatic species that lived 37 million years ago.

We witness the origins of what makes whales so unique in Dorudon. The animal’s features changed over time. Its nose moved back from its snout to the top of its head, its forelimbs became stiff flippers, its body grew longer, its hind limbs almost vanished, and it developed two rubbery flukes for a tail that moved up and down in the water instead of side to side like a fish’s tail does.

To accommodate its massive size, the blue whale underwent several alterations during its evolution from the dorudon. Here are some fascinating facts about the largest animal in the world.

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Evolutionary Advantages

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Breathing Deep

Blue whales require extremely effective lungs to survive because they can dive for up to an hour at a time and up to 100 meters below the surface. Two massive blowholes that are large enough for a tiny child to squeeze through facilitate the quick and effective exchange of oxygen in the largest animal in the world. Every time they breathe, blue whales exchange 80–90% of the oxygen in their lungs; humans only exchange 10–15% of this amount. 

Heart Beats

Its gigantic, four-chambered heart pumps oxygen throughout its massive body. The blue whale’s heart, which weighs about 900 kg and is about the size of a Mini car, beats once every 10 seconds, pumping 220 liters of blood through its body. The heartbeat is so loud that sonar equipment can hear it from three kilometers away.

Deeper Skin

Similar to fingerprints, the skin marks of a blue whale are distinct. The species gets its name from its pale bluish-grey color, yet depending on the light, the skin can alternatively seem tan or silvery grey. The length of the grooves on a blue whale’s throat and chest ranges from 80 to 100 meters.

No Tears

Blue whales are known to have limited vision, and their eyes are small compared to their total size—roughly the size of a grapefruit. They lack eyelashes and tear glands.

Sounding Board

Blue whales are said to have exceptional hearing despite without external ears; they are thought to sense sound through their bones and air sinuses. They use low-frequency whistles or rumbling noises to communicate, which have a louder sound than a passenger jet and can travel hundreds of kilometers at a decibel level of 188, suitable for the largest animal in the world.

Large Mouths

With each intake of water, their massive jaws, which are large enough to hold 100 humans, can take in tremendous amounts of prey. Stiff bristles that sprout from the roof of the mouth sift the nutrient-rich krill from the water that is spat. They consume as much as 6,000 kg of krill every day throughout the summer. 

Heating Up

Between the ages of five and ten is when blue whales reach sexual maturity. Prior to starting an intricate mating ritual in which the male and female roll over each other, dive deeply, and then abruptly swim to the surface to copulate, they search for warmer tropical waters, a perfect routine for the largest animal in the world. With a circumference of approximately 30 centimeters and a length of 3 meters when erect, the male penis is the largest in the animal kingdom. 

Unquenchable Thirst

As placental mammals, blue whales develop their fetus inside their mother’s uterus. The growing fetus reaches around 3.5 meters in length after seven months of rapid growth. At 12 months old, the about 2,700kg calf is born tail first and swims straight to the surface to breathe. It gains weight at a rate of ninety kilograms each day by sucking on its mother’s two nipples and consuming up to 180 liters of fat-rich milk per day, a rich diet for the largest animal in the world. When the calf is about 15 meters long, or seven or nine months old, weaning takes place.

Population Climbing

It is estimated that the number of blue whales was formerly over 250,000. There are currently thought to be between 10,000 and 25,000 remaining in the globe. They have been hunted for their meat, oil, and other lucrative body parts for decades, but the IUCN Red List now lists them as endangered. 

The largest mammal on Earth is the Antarctic blue whale (Balaenoptera musculus ssp. Intermedia), which may grow up to 98 feet long and weigh up to 400,000 pounds, or around 33 elephants, unsurprising for the largest animal in the world. The whale eats about 7936 pounds of krill a day during the primary feeding season; its heart is the size of a small car. Its sounds may reach 188 dB, compared to a jet engine’s 140 decibels, making it the loudest mammal on Earth. The whales most likely utilize their hundreds of miles-long low-frequency whistle to draw in other blue whales.


Beginning in the southern Atlantic Ocean in 1904, commercial whaling significantly decreased the number of blue whales in Antarctica. Illegal hunting persisted until 1972, despite being granted legal protection in the 1960s by the International Whaling Commission. The species’ population dropped from over 125,000 in 1926 to roughly 3,000 in 2018, placing it under the IUCN Red List’s “critically endangered” category despite being the largest animal in the world.

After recently visiting the sub-Antarctic island of South Georgia, a group of scientists under the direction of the British Antarctic Survey (BAS) had some positive news to give. They call the 55 Antarctic blue whales they counted on their 2020 expedition “unprecedented.” Even now, the South Georgia Waters are a crucial summer feeding ground.

“We are thrilled to see so many whales visiting South Georgia to feed again after three years of surveys,” says Dr. Jennifer Jackson, a whale ecologist at BAS. Whaling and sealing were both heavily practiced in this area. The fact that humpback whale populations are now comparable to those observed a century ago in South Georgia, where whaling first started, indicates that efforts to prevent whaling have been successful to save the largest animal in the world.

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How About the WWF?

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The Southern Ocean Commission (CCAMLR) and WWF have collaborated for many years to save the most vital habitats for iconic animals including seals, whales, penguins, seabirds, and the small Antarctic krill that serve as their food. In order to safeguard a variety of species that is being negatively impacted by climate change, including places where whales feed on Antarctic krill, CCAMLR has committed to establishing a network of marine protected areas surrounding Antarctica in the Southern Ocean. In order to assist governments safeguard these vital foraging regions, WWF collaborates with scientists to give vital information about the largest animal in the world.

The largest animal on Earth, Antarctic blue whales are a breathtaking sight to see in the wild. The real Antarctic giants are these whales, the largest animal in the world. They are very endangered, nevertheless, and are only just beginning to recover from the effects of whaling in the 20th century. Before it’s too late, we are currently trying to save the crucial blue whale feeding grounds in the Southern Ocean. According to Chris Johnson, Global Lead for the Protecting Whales & Dolphins Initiative, “this research reaffirms there is still hope.”

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A Fishy Diet

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The diet of blue whales, which is almost entirely made up of small shrimp-like creatures called krill, allows them to grow to these incredible proportions for the largest animal in the world. Approximately 4 tons of krill are consumed daily by a single adult blue whale during specific periods of the year.

Baleen, or fringed plates of material resembling fingernails, are linked to the top jaws of baleen whales, such as blue whales. The largest animal in the world spreads the pleated skin on their belly and throat to take in the water, which they first suck down with great force. The water is then forced out through the thin, overlapping baleen plates by the whale’s enormous tongue. Thousands of krill are ingested after being left behind.

While they appear completely blue underwater, blue whales are actually more of a mottled blue-gray on the surface. The millions of bacteria that settle in their epidermis give their underbellies a yellowish tint. The body of a blue whale is long and tapering, ending in wide, triangular flukes. Its head is broad and flat.

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Behavior and Booming Voices

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With the exception of the Arctic, blue whales inhabit every ocean on Earth. They mostly swim alone or in pairs, however they do occasionally form small groups of the largest animal in the world. When winter hits, they frequently migrate great distances towards the Equator, where they spend the summers eating in polar waters.

When they are angry, these beautiful swimmers may reach speeds of over 20 miles per hour while cruising the water at around five miles per hour. Among the world’s most noisy animals are blue whales, unsurprising for the largest animal in the world. It is believed that, under ideal circumstances, blue whales can hear one another up to 1,000 miles away from one another. They produce a variety of pulses, groans, and moans. Researchers believe that in addition to using their remarkable sense of hearing to sonar-navigate the dark ocean depths, these vocalizations are also used by them for communication.

When they are born, calves are already among the biggest animals on Earth. A young blue whale, up to three tons in weight and twenty-five feet in length, emerges from its mother’s womb after around a year, a massive size even for the largest animal in the world. For its first year, it feasts on nothing but mother’s milk, gaining almost 200 pounds every day.

Read More: What Is the Loudest Animal in the World?


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The longest-living creatures on Earth are blue whales. Researchers have found that they may approximate the age of a dead whale by counting the layers in its wax-like earplugs. It was calculated that the oldest blue whale discovered using this technique was approximately 110 years old. The average lifetime is thought to be between 80 and 90 years.

Whalers hunting for whale oil in the 1900s hunted whales aggressively to the point of extinction for the largest animal in the world. In the mid-1960s, some 360,000 blue whales were killed. This occurred between 1900. The 1966 International Whaling Commission brought them under protection, but since then, their recovery has only been marginal for the largest animal in the world.

Although they don’t have many predators, blue whales are known to be attacked by sharks and killer whales, and many of them are hurt or killed every year when they collide with big ships which tower over the largest animal in the world.

Ella is a digital content intern who loves writing about entertainment, media, technology, and culture. She is a recent... More about Ella Burch

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