Dolphins eat mostly fish and squid, they very in size between 1.2 for the smallest, Hector's dolphin (Cephalorhynchus hectori) at about 40kg to the largest and very powerful Orca (killer whale) at up to 9.5meters and 10 tonnes.
We can distinguish between freshwater dolphins and saltwater (oceanic) dolphins. Oceanic dolphins belong to the family delphinidae. Freshwater dolphins comprise four families with only one species each: Iniidae, Pontoporiidae, Lipotidae and Platanistidae.
| suborder | Family | Dolphin Species |
| Oceanic dolphins | Delphinidae | Rough toothed dolphin (Steno bredanensis) |
| | | Indo-Pacific humpback dolphin (Sousa chinensis) |
| | | Atlantic humpback dolphin (Sousa teuszii) |
| | | Indian humpback dolphin (Sousa plumbea) |
| | | Estuarine dolphin (Sousa guianensis) |
| | | White-beaked dolphin (Lagenorhynchus albirostris) |
| | | Atlantic white-sided dolphin (Lagenorhynchus acutus) |
| | | Dusky dolphin (Lagenorhynchus obscurus) |
| | | Pacific white-sided dolphin (Lagenorhynchus obliquidens) |
| | | Hourglass dolphin (Lagenorhynchus cruciger) |
| | | Peale's dolphin (Lagenorhynchus australis) |
| | | Risso's dolphin (Grampus griseus) |
| | | Bottlenose dolphin (Tursiops truncatus) |
| | | Atlantic spotted dolphin (Stenella frontalis) |
| | | Pantropical spotted dolphin (Stenella attenuata) |
| | | Spinner dolphin (Stenella longirostris) |
| | | Clymene dolphin (Stenella clymene) |
| | | Striped dolphin (Stenella coeruleoalba) |
| | | Common dolphin (Delphinus delphis) |
| | | Fraser's dolphin (Lagenodelphis hosei) |
| | | Northern right whale dolphin (Lissodelphis borealis) |
| | | Southern right whale dolphin (Lissodelphis peronii) |
| | | Commerson's dolphin (Cephalorhynchus commersonii) |
| | | Chilean dolphin (Cephalorhynchus eutropia) |
| | | Haviside's dolphin (Cephalorhynchus heavisidii) |
| | | Hector's dolphin (Cephalorhynchus hectori) |
| | | Melon-headed whale (Peponocephala electra) |
| | | Pygmy killer whale (Feresa attenuata) |
| | | False killer whale (Pseudorca crassidens) |
| | | Killer whale (Orcinus orca) |
| | | Long-finned pilot whale (Globicephala melas) |
| | | Short-finned pilot whale (Globicephala macrorhynchus) |
| | | Irrawaddy dolphin (Orcaella brevirostris) |
| | | Snubfin dolphin (Orcaella heinsohni) |
| Freshwater dolphins | Delphinidae | Tucuxi (Sotalia fluviatilis) |
| | Iniidae | Boto/Amazon river dolphin (Inia geoffrensis) |
| | Pontoporiidae | Franciscana (Pontoporia blainvillei) |
| | Lipotidae | Baiji/Chinese river dolphin (Lipotes vexillifer) |
| | Platanistidae | South Asian river dolphin (Platanista gangetica) |
| | | Indus River dolphin (Plantanista minor) |
Oceanic dolphin (Orca).
Freshwater Dolphin, "Lipotidae" ( Baiji/chinese river dolphin) now extinct.
