11 Facts About Blue Whales, the Largest Animals Ever on Earth

By Melissa Breyer, Updated July 07, 2020.

The blue whale, is the largest animal ever known to have lived on the planet. Here’s what you need to know about the majestic marine mammal.

Picture in your mind a 10-story-tall animal walking down the street and you probably start channeling images of Godzilla or King Kong. But if you imagine it as a marine mammal and place it on its side, swimming ... now you’ve got a blue whale.

Balaenoptera musculus, the blue whale, is the largest animal ever known to have lived on the planet – larger than dinosaurs, and movie monsters aside. Even at birth it is one of the world’s biggest animals!.The planet is covered with amazing, fascinating creatures, but the blue whale ranks among one of the most superlative. Consider the following.

1. How big is a blue whale?
They are gigantic. Generally ranging in length from 80 to 100 feet (24 to 30 meters), the longest one ever recorded was a magnificent 108 feet long. 2. How much does a blue whale weigh? These gentle giants weigh up to 200 tonnes, or around 441,000 pounds. 3. They’ve got big hearts The blue whale's heart is huge! It is about 5 feet long, 4 feet wide, and 5 feet tall and weighs around 400 pounds; its beat can be detected from two miles away.

4. ...and tongues
A blue whale’s tongue alone weighs as much as an elephant.

5. How big are blue whale babies?
Blue whale calves are the biggest babies on Earth, easily, and at birth already rank amongst the largest full-grown animals. They pop out at around 8,800 pounds with a length of some 26 feet. They gain 200 pounds a day! Their growth rate is likely one of the fastest in the animal world, with a several billion-fold increase in tissue in the 18 months from conception to weaning.

6. They’re loud … and make long-distance calls for free Blue whales, in fact, are the loudest animals on the planet. A jet engine registers at 140 decibels, the call of a blue whale reaches 188. Their language of pulses, groans, and moans can be heard by others up to 1,000 miles (1,600 kilometers) away.

7. What do blue whales eat?
Blue whales feast on krill; their stomachs can hold 2,200 pounds of the tiny crustaceans at a time. They require almost 9,000 pounds of the little guys a day; and around 40 million krill daily during the summer feeding season. 8. Are blue whales fast? They travel a lot, spending summers feeding in polar regions and making the long trip to the Equator as winter comes along. While they have a cruising speed of 5 MPH, they can accelerate up to 20 MPH when needed.

credit: NOAA Photo LibraryNOAA Photo Library/CC BY 2.0

9. They’ve got long lives
While not nearly as old as the Earth’s oldest trees, blue whales are among the planet’s longest-lived animals. Kind of like counting tree rings, scientists count layers of wax in the ears and can determine a ballpark age. The oldest they’ve discovered this way was calculated to be around 100 years old, though the average life is thought to be around 80 to 90 years.

10. They were once numerous
Before whalers discovered the treasure trove of oil that a blue whale could provide, the numbers were generous. But with the advent of 20th century whaling fleets, nearly every last one of them was killed before receiving worldwide protection in 1967. According to WWF, from 1904 to 1967, more than 350,000 were killed in the Southern Hemisphere. In 1931, during the heyday of whaling, an astounding 29,000 blue whales were killed in a single season.

11. Their future is unclear
While commercial whaling is no longer a threat, recovery has been slow and new threats plague blue whales, like ship strikes and the impact of climate change. There is one population of around 2,000 blue whales off the coast of California – but all told there are only around 10,000 to 25,000 individuals left. The World Conservation Union (IUCN) Red List rates them as Endangered. Hopefully with time, the planet’s giantest gentle giants will again roam the seas aplenty.

Sources: WWF, Natoinal Geographic