They are the largest animals to have ever lived — bigger than the biggest dinosaurs. A blue whale can reach up to ~30 meters (98 feet) long and weigh around 180 tons.
Their heart is about the size of a small car, and it can weigh over 180 kg (400 lbs). You could theoretically crawl through their major arteries.
A blue whale’s tongue alone can weigh as much as an elephant.
They eat tiny food for such massive animals. Blue whales survive almost entirely on krill, eating up to 4 tons per day during feeding season.
They are among the loudest animals on Earth. Their calls can reach over 180 decibels and travel hundreds of kilometers underwater.
Their babies are enormous. A newborn calf is about 7–8 meters (23–26 ft) long and gains ~90 kg (200 lbs) per day from drinking its mother’s milk.
Their heartbeats are slow. When diving, a blue whale’s heart can slow to 2 beats per minute to conserve oxygen.
They can live 80–90 years or more, and scientists estimate age by counting layers in earwax plugs (yes, really).
They were nearly hunted to extinction in the 20th century due to whaling. While populations are slowly recovering, they’re still classified as endangered.
Despite their size, they’re graceful swimmers, cruising efficiently across entire oceans during long migrations.