Cetacea is a group of marine mammals that includes whales, dolphins, and porpoises. These animals are known for their streamlined bodies and adaptations for life in the water, such as the ability to hold their breath for long periods. They are warm-blooded, breathe air through lungs, and give live birth, making them unique among ocean creatures. Cetaceans are highly intelligent and social animals, often living in groups called pods. They communicate using a variety of sounds, including clicks and whistles. Many species, like the bottlenose dolphin, are known for their playful behavior and strong bonds with one another, showcasing the complexity of their social structures.