Blue Whales (Balaenoptera musculus) are the largest animals ever to have lived on Earth, with a heart the size of a small car and a body length of up to 30 meters (100 feet). They are baleen whales, feeding primarily on krill, consuming up to 4 tonnes of these tiny crustaceans daily during feeding seasons. Using their pleated throat grooves, they gulp vast amounts of water, filtering out krill through their baleen plates. Despite their colossal size, blue whales are remarkably graceful swimmers, capable of reaching speeds of up to 32 kilometres per hour (20 mph) when necessary. They produce low-frequency vocalisations that can travel hundreds of kilometres (miles) underwater, helping them communicate across vast ocean distances. Blue whales are widely distributed across most of the world's oceans. They migrate seasonally between colder feeding grounds and warmer breeding areas. Blue whales were once hunted almost to the point of extinction by the commercial whaling industry. Luckily, conservation efforts have helped their numbers slowly recover.