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Types of Dolphins

Priya Johnson
It's ironic that oceanic dolphins are more popular than river dolphins, especially because it's the latter who are in dire need of attention. In this particular story, we will shed light on different types of dolphins in a bid to make readers aware of the fact that the world of these cetaceans goes well beyond the bottlenose species.

Lost in translation!

Killer whales are actually dolphins and not whales. Long story short, the Spanish sailors used to call them 'Matador de Ballenas', which can be loosely translated to killer of whales. The 'of' in that phrase, has since been lost in translation.
When we hear the word 'dolphin', what comes to mind is the endearing and highly intelligent bottlenose dolphin shown in movies and television shows. The fact though, is that there are 42 different species of dolphins, ranging from the Hector's dolphin, which happens to be the smallest dolphin in the world, to the Orca or killer whale, which happens to be the largest of all dolphin species.

Different Types of Dolphins

The 42 extant dolphin species are grouped into 4 types, based on various factors, including which part of the world they are found in and what type of water they inhabit.
So, we have dolphins that inhabit oceans, like the famous bottlenose dolphins and killer whales, as well as ones that inhabit freshwater sources, like the Amazon river dolphin and South Asian river dolphin. While the Amazon river dolphin is a New World species, the South Asian river dolphin is an Old World species.
In short, there is a great deal of diversity when it comes to the world of these marine mammals.
CR Critically Endangered
VU Vulnerable
LC Least Concern
EN Endangered
NT Near Threatened
DD Data Deficient

Oceanic Dolphin Species

Species: Scientific Name (Status) - Range

Atlantic humpback dolphin: Sousa teuszii (VU) - Endemic to the eastern tropical Atlantic Ocean

Atlantic spotted dolphin: Stenella frontalis (DD)- Found in the Gulf Stream of the North Atlantic Ocean

Atlantic white-sided dolphin: Lagenorhynchus acutus (LC)- Found in the North Atlantic Ocean

Species : Scientific Name (Status) - Range

Australian snubfin dolphin: Orcaella heinsohni (NT) - Found off the northern coast of Australia

Burrunan dolphin: Tursiops australis (NA*) - Found off-coast Victoria, Australia

Chilean dolphin: Cephalorhynchus eutropia (NT) - Found off-coast Chile

Clymene dolphin: Stenella clymene (DD) - Found in the Atlantic Ocean

Species : Scientific Name (Status) - Range

Commerson's dolphin: Cephalorhynchus commersonii (DD) - Found along the southern coast of South America; near the Kerguelen Islands in the Indian Ocean

Common bottlenose dolphin: Tursiops truncatus (LC) - Found in temperate and tropical waters worldwide

Species : Scientific Name (Status) - Range

Costero: Sotalia guianensis (DD) - Found off-coast northern and eastern South America and eastern Central America

Dusky dolphin: Lagenorhynchus obscurus (DD) - Found off-coast South America, southwestern Africa, southern Australia, and New Zealand

False killer whale: Pseudorca crassidens (DD) - Found in temperate and tropical waters worldwide

Species : Scientific Name (Status) - Range

Fraser's dolphin: Lagenodelphis hosei (LC) - Inhabits deep tropical waters of the Pacific Ocean

Heaviside's dolphin: Cephalorhynchus heavisidii (DD)- Found along the southwestern coast of Africa

Hector's dolphin: Cephalorhynchus hectori (EN)- Endemic to the coastal regions of New Zealand

Species : Scientific Name (Status) - Range

Hourglass dolphin: Lagenorhynchus cruciger (LC)- Inhabits Antarctic and sub-antarctic waters

Indian humpback dolphin: Sousa plumbea (NT) - Found in the Indian Ocean; from South Africa to the east coast of India

Indo-Pacific bottlenose dolphin: Tursiops aduncus (DD)- Found off-coast India, northern Australia, South China, and the eastern coast of Africa

Species : Scientific Name (Status) - Range

Irrawaddy dolphin: Orcaella brevirostris (VU) - Inhabits the waters of Bay of Bengal and Southeast Asia

Killer whale (orca): Orcinus orca (DD) - Found all over the world

Long-beaked common dolphin: Delphinus capensis (DD)- Disjointed range in warm-temperate and tropical oceans

Species : Scientific Name (Status) - Range

Long-finned pilot whale: Globicephala melas (DD)- Found in the North Atlantic and parts of the Southern Hemisphere

Melon-headed whale: Peponocephala electra (LC) - Found in tropical waters around the world

Northern right whale dolphin: Lissodelphis borealis (LC) - Found in the North Pacific Ocean

Species : Scientific Name (Status) - Range

Indo-Pacific humpbacked dolphin: Sousa chinensis (NT) - Inhabits waters of the Indian and Pacific Oceans; east coast of India to China and Australia

Pacific white-sided dolphin: Lagenorhynchus obliquidens (LC) - Found in the North Pacific Ocean

Pantropical spotted dolphin: Stenella attenuata (LC)- Found in temperate and tropical waters worldwide

Species : Scientific Name (Status) - Range

Peale's dolphin: Lagenorhynchus australis (DD)- Endemic to the coastal waters around southern South America

Pygmy killer whale: Feresa attenuata (DD) - Inhabits tropical and subtropical waters around the world

Risso's dolphin: Grampus griseus (LC) - Found in temperate and tropical waters worldwide

Species : Scientific Name (Status) - Range

Rough-toothed dolphin: Steno bredanensis (LC) - Found in tropical waters around the world

Short-beaked common dolphin: Delphinus delphis (LC) - Found in warm-temperate and tropical oceans worldwide

Short-finned pilot whale: Globicephala macrorhynchus (DD) - Found in warm-temperate and tropical oceans worldwide

Species : Scientific Name (Status) - Range

Southern right whale dolphin: Lissodelphis peronii (DD)- Inhabits cold water of temperate and polar regions in the Southern Hemisphere

Spinner dolphin: Stenella longirostris (DD) - Found in tropical waters around the world

Striped dolphin: Stenella coeruleoalba (LC) - Found in temperate and tropical waters worldwide

Species : Scientific Name (Status) - Range

Tucuxi: Sotalia fluviatilis (DD) - Endemic to the Amazon Basin

White-beaked dolphin: Lagenorhynchus albirostris (LC)- Endemic to the North Atlantic Ocean

Species- Scientific Name - Range – Status

Amazon river dolphin - Inia geoffrensis - The Orinoco, Amazon, and Araguaia/Tocantins River systems - DD

Araguaian river dolphin - Inia araguaiaensis - The Araguaia-Tocantins basin -NA*

Species - Scientific Name - Range – Status

South Asian river dolphin - Platanista gangetica - River systems of India, Pakistan, Bangladesh, and Nepal - EN

Species - Scientific Name - Range - Status

La Plata dolphin - Pontoporia blainvillei - The Río de la Plata estuary and coastal waters along the Atlantic coast - VU
Of the four river dolphin species, the first three reside in freshwater rivers, while the La plata dolphin dwells in the salt-water estuary. Extant river dolphins do not bear much semblance to their oceanic cousins. 
Their beaks are extremely large, even forming one-fifth of the total body length in some species. They have extremely well-developed brains and short, broad flippers. Moreover, they are almost blind, which makes sense, considering that they live in muddy water and hence, do not need vision.

Porpoises (Family Phocoenidae)

Despite all the similarities, porpoises are different from dolphins. They are smaller and have short, blunt snouts. They are often referred to as small dolphins by sailors and fishermen. The six extant species of porpoises are...
  • Burmeister's porpoise (Phocoena spinipinnis)
  • Dall's porpoise (Phocoenoides dalli)
  • Finless porpoise (Neophocaena phocaenoides)
  • Harbor porpoise (Phocoena phocoena)
  • Spectacled porpoise (Phocoena dioptrica)
  • Vaquita porpoise (Phocoena sinus)
If they have not been able to emerge independently, it might have something to do with the fact that they have been overshadowed by dolphins, their popular cousins.
The Indo-Pacific humpback dolphin, Amazon river pink dolphin, and the Indus river dolphin are on the brink of extinction, while the Yangtze river dolphin (A.K.A. Baiji) has been declared functionally extinct.
River dolphins in particular are at a greater risk because of river pollution, increasing river traffic, constructions of dams, destruction of tropical rainforests, etc. Oceanic dolphins too, have a whole lot of woes of their own; noise pollution resulting from marine transportation being one of them.
Various volunteer programs and organizations have dedicated themselves to the noble cause of saving these dolphins, but then, the fact that we have neglected the species for so long means it won't be an easy task.