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

Mysterious, enormous, and vital to our marine ecosystems, blue whales have been roaming our oceans for centuries. The planet is covered with amazing, fascinating creatures, but the blue whale is in a league of its own.

Balaenoptera musculus is the largest animal ever known to have lived on the planet, including all dinosaurs. Even at birth, it's bigger than adults from most other animal species. However, that's just the tip of the iceberg of blue whale knowledge that's compelling, confounding, and maybe even a bit mind-blowing.

1. Blue Whales Can Grow More Than 100 Feet Long

Blue whales are gigantic, generally ranging in length from 80 to 100 feet (24 to 30 meters). The longest accurately measured blue whale is a female who clocked in at 97 feet (23.5 meters)—but there are reports of blue whales that reached 108 feet (33 meters) in length. Just how big is that? Imagine three school buses back-to-back!

2. They Can Weigh as Much as 30 Elephants

The average weight for blue whales is 200,000 to 300,000 pounds (90,000 to 136,000 kilograms), or about 100 to 150 tons. Some can weigh as much as 441,000 pounds (200,000 kilograms) or 220 tons. For comparison, an adult African bush elephant weighs up to 6 tons, so it may take 30 or more elephants to equal the weight of one blue whale.

3. They Have Big Hearts

The blue whale's heart is huge. It's the largest heart in the animal kingdom, weighing about 400 pounds (180 kilograms)—about the same weight as a gorilla and roughly the size of a bumper car. As a blue whale dives to feed, its giant heart may only beat twice per minute.

4. They Have Big Tongues, Too

A blue whale’s tongue alone can weigh as much as an elephant.

5. They Have the Biggest Babies on Earth

Blue whale calves are the biggest babies on Earth, easily, and at birth already rank among the largest full-grown animals. They pop out at around 8,800 pounds (4,000 kg) with a length of some 26 feet (8 meters). They gain 200 pounds (90 kg) 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 Unusually Loud

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 180. Their language of pulses, groans, and moans can be heard by others up to 1,000 miles (1,600 kilometers) away.

7. They Eat a Lot of Krill

Blue whales feast on krill; their stomachs can hold 2,200 pounds (1,000 kilograms) of the tiny crustaceans at a time. They require almost 9,000 pounds (4,000 kilograms) of the little guys a day and around 40 million krill daily during the summer feeding season.

8. They're Pretty Fast

Blue whales 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 (8 kph), they can accelerate up to 20 mph (32 kph) when needed.

9. They Have Long Life Spans

Blue whales are among the planet’s longest-lived animals. Kind of like counting tree rings, scientists count layers of wax in their ears and can determine a ballpark age. The oldest blue whale 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 Once Were Abundant

Before whalers discovered the treasure trove of oil that a blue whale could provide, the species was plentiful. But with the advent of 20th-century whaling fleets, their population plummeted until finally receiving worldwide protection in 1967. From 1904 to 1967, more than 350,000 blue whales were killed in the Southern Hemisphere, according to the World Wildlife Fund. In 1931, during the heyday of whaling, an astounding 29,000 blue whales were killed in a single season.

11. Their Future Remains Uncertain

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 individual creatures left. The International Union for Conservation of Nature lists the species as endangered. Hopefully, with time, the planet’s largest gentle giants will again roam the seas aplenty.