Blue Whale

The blue whale (Balaenoptera musculus) is the largest known animal to have ever lived on Earth. They can reach lengths of 30 meters (100 feet) — longer than three school buses — and weigh up to 200 metric tons (441,000 pounds). Their hearts alone weigh as much as a car and can be heard from 2 miles away. Their tongues weigh more than an elephant. Their call, at up to 188 decibels, is the loudest sound produced by any animal. Despite their enormous size, blue whales eat almost exclusively krill — tiny shrimp-like crustaceans — consuming up to 40 million krill (3,600 kg) per day during feeding season. Blue whales were nearly hunted to extinction in the early 20th century. At their lowest, only about 400-1,000 remained. International protections since 1966 have allowed recovery, with current populations estimated at 10,000-25,000. They are still classified as endangered.