The largest mammal on Earth is the blue whale (Balaenoptera musculus).

Blue whale (Balaenoptera musculus), largest mammal on Earth

• Blue whales can grow up to 100 feet long and weigh up to 200 tons, which is more than 33 elephants. Their tongues alone can weigh as much as an elephant.
• Blue whales are baleen whales, which means they have baleen plates in their mouths instead of teeth. Baleen plates are made of keratin, the same material that makes up human hair and nails. Blue whales use their baleen plates to filter food from the water.
• Blue whales are filter feeders, meaning they eat tiny organisms called plankton. They can filter up to 4 tons of water per hour.
• Blue whales are found in all of the world's oceans, but they are most common in the Southern Ocean.
• Blue whales are an endangered species. They were hunted extensively for their blubber and baleen in the 19th and 20th centuries. The population of blue whales has declined by more than 90% since commercial whaling began.

Today, blue whales are protected by international law. However, they still face threats from ship strikes, pollution, and climate change.

Blue whales are an important part of the marine ecosystem. They help to keep plankton populations in check, which supports other marine life. Blue whales are also a popular tourist attraction.