The Order Cetacea comprises fully aquatic mammals including whales, dolphins, and porpoises. Cetaceans are highly adapted to life in water, with streamlined bodies, flippers, tail flukes for propulsion, and a blowhole for breathing. They are warm-blooded, air-breathing, and give live birth, with most species exhibiting complex social behaviors and communication, especially dolphins. Cetaceans are carnivorous, feeding on fish, squid, or plankton depending on the species, and many undertake long migrations. Ecologically, they play vital roles in marine food webs and nutrient cycling, while also being culturally and economically significant to humans.