Cetaceans are a group of marine mammals that include whales, dolphins, and porpoises. They are known for their streamlined bodies and adaptations for life in the water, such as the ability to hold their breath for long periods. Cetaceans are warm-blooded and breathe air through lungs, which they do using a blowhole located on the top of their heads. These animals are highly social and often live in groups called pods. Cetaceans communicate using a variety of sounds, including clicks and whistles, which they use for navigation and social interaction. They play important roles in marine ecosystems and are often studied for their intelligence and complex behaviors.