How many species of dolphins are there?

Currently there are 49 dolphin and porpoise species which are grouped into six families: the oceanic dolphin family is by far the largest with 38 members; the porpoise family has seven members; and there are four river dolphin families, each containing just one species. However, classification is not an exact science and as more information and discoveries come to light, deliberations will continue and some dolphin species are likely to be further split into more than one species and/or subspecies.

Names and nick names can certainly be confusing; there are eight dolphin names that feature the word ‘whale’, including pilot whales, killer whales, false killer whales and melon-headed whales. Two species have whale and dolphin in their name; the northern right whale dolphin and the southern right whale dolphin – no wonder both the public and scientists get confused!

Where do dolphins live?

Dolphins live in the world’s seas and oceans and in some rivers too. Some dolphin species prefer to live in coastal areas, others like shallow water but prefer to live away from the coast close to patches of shallower water which are located further out to sea.

Orcas are the only dolphins which live in the Arctic and Antarctic’s Southern oceans. Their large size means that they have more protection against the harsh cold of the freezing seas. Most dolphins prefer tropical and temperate waters as they are warm-blooded mammals and so it is easier for them to regulate their body temperature in these environments.

Can dolphins live in fresh water?

River dolphins such as the Amazon River dolphin (boto) and South Asian river dolphins live their lives only in fresh water rivers and lakes, a long way from the ocean; they are sometimes known as the ‘true river dolphins’. There is another group of so-called river dolphins; these are fresh water populations of marine dolphin species some of whom permanently live in fresh water rivers, these include the tucuxi (or sotalia), the Guiana dolphin, Irrawaddy dolphin and the finless porpoise.