This family of 17 Recent genera and 34 species inhabits all the oceans and adjoining seas of the world, as well as the estuaries of many large rivers.
Some species occasionally ascend rivers.
Head and body length ranges from as little as 139 cm in some specimens of Sotalia to as much as 980 cm in Orcinus, and weight in full-grown individuals ranges from about 50 to 9,000 kg. The blowhole is located well back from the tip of the beak or the front of the head. The pectoral and dorsal fins are sickle-shaped, triangular, or broadly rounded, and the dorsal fin is located near the middle of the back. The genus Lissodelphis lacks a dorsal fin. In the Delphinidae the vertebrae number 50-100 and the first 2 neck vertebrae are fused, whereas in the Iniidae, Lipotidae, Pontoporiidae, and Platanistidae all the neck vertebrae are free.