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Types & Species of Dolphins

Instructor: Wendy McDougal

Wendy has taught high school Biology and has a master's degree in education.

Dolphins are some of the most recognized marine mammals in the sea. It is a unique group, with a wide variety of appearances and habitats. Read on to learn more about the many different species of dolphin.

Dolphins: A Diverse and Unique Group

Of all the water-dwelling mammals, there is one that stands out for its intelligence, playfulness and complex social behavior. It is the dolphin, a mammal belonging to the order Cetacea. Dolphins are closely related to the whale. We tend to picture dolphins as sleek and gray, leaping from the water with a clever grin. However, with over forty different species, this is an extremely diverse group. Let's take a closer look at the many species of dolphin.

When we picture a dolphin, we often imagine one such as this bottlenose
dolphin

Dolphin Families

When classifying dolphins, there are several groups and subgroups. As previously mentioned, dolphins belong to order Cetacea, which includes whales. They are further classified into suborder Odonotoci, literally meaning ''toothed whale.'' Characterized as having a blowhole, teeth and a fatty melon in their foreheads for echolocation, this group includes both dolphins and porpoises.

Further narrowing it down, family Delphinidae is made up of marine dolphins. Members of this family usually have a prominent beak, large dorsal fin and conical-shaped teeth. However, these characteristics vary greatly among the species. Two other families, Iniidae and Platanistidae contain the lesser known river dolphins. These dolphins are found in freshwater and tend to have longer beaks and smaller dorsal fins than their marine cousins.

Marine Dolphin Species

The ocean-dwelling family of dolphins contains about 37 different species. When you imagine a dolphin, you are most likely picturing one of two species belonging to genus Delphinus. These are the long-beaked and short beaked common dolphins. Bottlenose dolphins, two species belonging to genus Tursiops, also fit the portrait of the traditional dolphin.

Genus Cephalorhynchus includes four species that have quite different appearances from common dolphins. All are found in the Southern hemisphere. Commerson's, Chilean, Heaviside's and New Zealand dolphins are relatively small and stocky. Some are even black and white in color. Genus Lagenodelphis contains a species known as Fraser's dolphin with a similar stocky body type.

Genus Lagenorhynchus represents a large group, with six dolphin species: Atlantic white-sided, white-beaked, Peale's, hourglass, Pacific white-sided and dusky. These dolphins lack the prominent beak of common dolphins, having instead more of a snub nose. They are often found in colder waters, unlike many other dolphins.

In genus Stenella is a unique group characterized by five species that are spotted or striped, and quite talented. The pantropical spotted, Atlantic spotted, clymene, striped and spinner dolphins are all included here. The spinner dolphin is acrobatic and entertaining as it leaps from the water and spins quickly.

You may have heard of humpback whales, but did you know there are also humpback dolphins? Genus Sousa contains the Indo-Pacific humpback dolphin and the pantropical spotted dolphin. Speaking of whales, there are a number of dolphins that have ''whale'' in their name. Genus Lissodelphis contains two species, the northern right-whale dolphin and southern right-whale dolphin. The northern variety is the only dolphin that completely lacks a dorsal fin.

Continuing with the dolphins that quite look like whales, we find six dolphin species that are often referred to as ''blackfish.'' In genus Globicephala we find the short-finned pilot whale and the long-finned pilot whale. And genus Peponocephala is the melon-headed whale, which is actually a dolphin. These are tricky animals to identify in that they truly look like whales, lacking the traditional beak of the dolphin.

The orca is not a whale at all, but a dolphin
Orcas

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