The scientific name for the Irrawaddy dolphin is Orcaella brevirostris.

Adult snubfins (Orcaella heinsohni) appear to be about 5 feet long, by the comparison displayed in the related link listed below:

It may be hard to believe but there are approximately 36 different species of dolphins. There are 32 marine dolphins which live in oceans and salt water habitats and there are 4 river dolphins. If you add in the 6 porpoise species then there are 42 species. Some species of dolphins are bottlenose, white beaked, black, dusky, and Atlantic white-sided.

Suborder Odontoceti, toothed whales

Family Delphinidae, oceanic dolphins

Genus Delphinus
Long-Beaked Common Dolphin, Delphinus capensis
Short-Beaked Common Dolphin, Delphinus delphis

Genus Tursiops
Bottlenose Dolphin, Tursiops truncatus
Indo-Pacific Bottlenose Dolphin, Tursiops aduncus

Genus Lissodelphis
Northern Rightwhale Dolphin, Lissodelphis borealis
Southern Rightwhale Dolphin, Lissiodelphis peronii

Genus Sotalia
Tucuxi, Sotalia fluviatilis
Costero, Sotalia guianensis

Genus Sousa
Indo-Pacific Hump-backed Dolphin, Sousa chinensis
Chinese White Dolphin (the Chinese variant), Sousa chinensis chinensis
Atlantic Humpbacked Dolphin, Sousa teuszii

Genus Stenella
Atlantic Spotted Dolphin, Stenella frontalis
Clymene Dolphin, Stenella clymene
Pantropical Spotted Dolphin, Stenella attenuata
Spinner Dolphin, Stenella longirostris
Striped Dolphin, Stenella coeruleoalba

Genus Steno
Rough-Toothed Dolphin, Steno bredanensis

Genus Cephalorynchus
Chilean Dolphin, Cephalorhynchus eutropia
Commerson's Dolphin, Cephalorhynchus commersonii
Heaviside's Dolphin, Cephalorhynchus heavisidii
Hector's Dolphin, Cephalorhynchus hectori

Genus Grampus
Risso's Dolphin, Grampus griseus

Genus Lagenodelphis
Fraser's Dolphin, Lagenodelphis hosei

Genus Lagenorhyncus
Atlantic White-Sided Dolphin, Lagenorhynchus acutus
Dusky Dolphin, Lagenorhynchus obscurus
Hourglass Dolphin, Lagenorhynchus cruciger
Pacific White-Sided Dolphin, Lagenorhynchus obliquidens
Peale's Dolphin, Lagenorhynchus australis
White-Beaked Dolphin, Lagenorhynchus albirostris

Genus Orcaella
Australian Snubfin Dolphin, Orcaella heinsohni
Irrawaddy Dolphin, Orcaella brevirostris

Genus Peponocephala
Melon-headed Whale, Peponocephala electra

Genus Orcinus
Killer Whale (Orca), Orcinus orca

Genus Feresa
Pygmy Killer Whale, Feresa attenuata

Genus Pseudorca
False Killer Whale, Pseudorca crassidens

Genus Globicephala
Long-finned Pilot Whale, Globicephala melas
Short-finned Pilot Whale, Globicephala macrorhynchus

Family Platanistoidea, river dolphins

Genus Inia
Amazon River Dolphin (Boto), Inia geoffrensis

Genus Lipotes
Chinese River Dolphin (Baiji), Lipotes vexillifer (considered functionally extinct)

Genus Platanista
Ganges River Dolphin, Platanista gangetica
Indus River Dolphin, Platanista minor

Genus Pontoporia
La Plata Dolphin (Franciscana), Pontoporia blainvillei

There are 41 species of dolphin in the family delphindae. Which is the family for dolphins.

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According to wikispecies, there are 41 species of dolphins of the family delphinade or oceanic dolphins.

Family Delphinidae, oceanic dolphins:

Long-Beaked Common Dolphin, Delphinus capensis

Short-Beaked Common Dolphin, Delphinus delphis

Bottlenose Dolphin, Tursiops truncatus

Indo-Pacific Bottlenose Dolphin, Tursiops aduncus

Northern Rightwhale Dolphin, Lissodelphis borealis

Southern Rightwhale Dolphin, Lissiodelphis peronii

Tucuxi, Sotalia fluviatilis

Indo-Pacific Hump-backed Dolphin, Sousa chinensis

Chinese White Dolphin (the Chinese variant), Sousa chinensis chinensis

Atlantic Humpbacked Dolphin, Sousa teuszii

Atlantic Spotted Dolphin, Stenella frontalis

Clymene Dolphin, Stenella clymene

Pantropical Spotted Dolphin, Stenella attenuata

Spinner Dolphin, Stenella longirostris

Striped Dolphin, Stenella coeruleoalba

Rough-Toothed Dolphin, Steno bredanensis

Chilean Dolphin, Cephalorhynchus eutropia

Commerson's Dolphin, Cephalorhynchus commersonii

Heaviside's Dolphin, Cephalorhynchus heavisidii

Hector's Dolphin, Cephalorhynchus hectori

Risso's Dolphin, Grampus griseus

Fraser's Dolphin, Lagenodelphis hosei

Atlantic White-Sided Dolphin, Lagenorhynchus acutus

Dusky Dolphin, Lagenorhynchus obscurus

Hourglass Dolphin, Lagenorhynchus cruciger

Pacific White-Sided Dolphin, Lagenorhynchus obliquidens

Peale's Dolphin, Lagenorhynchus australis

White-Beaked Dolphin, Lagenorhynchus albirostris

Australian Snubfin Dolphin, Orcaella heinsohni

Irrawaddy Dolphin, Orcaella brevirostris

Melon-headed Whale, Peponocephala electra

Killer Whale (Orca), Orcinus orca

Pygmy Killer Whale, Feresa attenuata

False Killer Whale, Pseudorca crassidens

Long-finned Pilot Whale, Globicephala melas

Short-finned Pilot Whale, Globicephala macrorhynchus

Boto (Amazon River Dolphin), Inia geoffrensis

Chinese River Dolphin (Baiji), Lipotes vexillifer (considered functionally extinct)

Ganges River Dolphin, Platanista gangetica

Indus River Dolphin, Platanista minor

La Plata Dolphin (Franciscana), Pontoporia blainvillei

Some also say there's only 32 of them.