Cetaceans are marine mammals that include whales, dolphins, porpoises, and sperm whales. Evolving around 50 million years ago from land-dwelling ancestors, this large group is divided into two main suborders: mysticetes, or baleen whales, which filter their food from the water, and odontocetes, or toothed whales, which hunt fish, squid, and other prey using echolocation. Found in oceans all around the world, cetaceans play a vital role in maintaining the balance of marine ecosystems and continue to fascinate scientists and the public alike with their intelligence, complex social behavior, and remarkable long-distance migration abilities.