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 distinguishes them from fish. These animals are highly intelligent and often exhibit complex social behaviors. Many cetaceans communicate using a variety of sounds, and some species, like the bottlenose dolphin, are known for their playful nature. Cetaceans play a crucial role in marine ecosystems and are often studied for their behaviors and conservation needs.