A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and possibly extinct Lipotidae. There are 40 extant species named as dolphins.
A common bottlenose dolphin (Tursiops truncatus)
The face of a common bottlenose dolphin
A pod of Indo-Pacific bottlenose dolphins in the Red Sea
Dolphins surfing at Snapper Rocks, Queensland, Australia
Cetacea is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver.
Cetacea
Skull of the North Atlantic right whale (Mysticeti)
Skull of the orca (Odontoceti)
Head profile of a beluga whale, featuring the large "melon" region