What is the world's largest type of whale by weight?

The world's largest whale by weight is the blue whale (Balaenoptera musculus). Adult blue whales can weigh anywhere from 100 to 200 tons (200,000 to 400,000 pounds) and can grow up to 100 feet in length. That makes them not only the largest whale but the largest animal on the planet.

The blue whale is a baleen whale and feeds on krill, small shrimp-like animals. Despite its enormous size, the blue whale feeds by swimming through swarms of krill with its mouth open, filtering them through the baleen plates in its mouth.

Blue whales can be found in all of the world's oceans, though they were heavily hunted during the 20th century and their populations are still recovering today. They are now protected under international law, and conservation efforts have helped their populations to slowly increase in some areas.