The blue whale is not just the largest animal in the ocean; it is the biggest animal known to have ever lived on Earth. It grows larger than even the biggest dinosaurs. These massive marine mammals can reach lengths of 100 feet (30 meters) and weigh as much as 200 tons. Their tongue alone weighs as much as an entire elephant.

A Car-Sized Heart

Inside this giant body beats the largest heart in the animal kingdom. It is roughly the size of a small car, such as a bumper car, and weighs nearly 1,000 pounds (450 kilograms). Because the heart is so massive, it pumps blood very slowly compared to smaller animals. When a blue whale dives deep into the ocean to hunt, its heart might beat only four to eight times per minute.

Thunderous Calls

Blue whales are the loudest animals on the planet. Their low-frequency whistles and pulses can reach 188 decibels. This is louder than a jet engine taking off. While humans cannot hear the lowest sounds they make, other whales can hear them up to 1,000 miles (1,600 kilometers) away underwater. They use these powerful sounds to communicate across vast oceans.

Feeding on the Smallest

Despite their incredible size, blue whales eat tiny shrimp-like animals called krill. They do not have teeth. Instead, they have fringed plates called baleen hanging from their upper jaws. The whale opens its mouth wide to gulp a huge mouthful of water and krill. It then pushes the water out through the baleen bristles, which trap the food inside like a net. During the feeding season, a single blue whale can eat up to 4 tons of krill in one day.