What Is a Dolphin?

A Favorite Marine Mammal

Bottlenose dolphin jumping Bottlenose dolphin
Martin Ruegner/Photographer's Choice/Getty Images

Many of us know what a dolphin looks like, but there are plenty of interesting facts about dolphins. Did you know that dolphins are considered whales? Learn more about these remarkable, lovable marine mammals.

A dolphin is one of 38 species of Odontocete, which is a toothed whale. These species are categorized in the Family Delphinidae. You might be surprised to know that the killer whale, or orca, is also considered a dolphin.

Dolphins range in size from 5 feet (such as the spinner dolphin) to 30 feet (orca).

Characteristics of Dolphins

Dolphins have these characteristics:

  • Streamlined bodies. Like other whales, dolphins swim by moving their tail up and down, thus propelling themselves forward. The form (wide in the middle, more pointed at each end) of the dolphin's body increases the ability of water to slide over it as the dolphin swims, helping it swim faster.

  • A pronounced beak. Rather than a squared-off or gradually-tapering head, dolphins have an obvious beak-like rostrum.

  • Cone-shaped teeth. Rather than spade-shaped, or flat teeth, such as porpoises exhibit.

  • One blowhole. Though you can compare this to baleen whales, who have two blowholes.

  • Dorsal fin. Like many other cetaceans, most dolphins also have a dorsal fin on their back and two pectoral fins.

  • Mammalian temperature. A dolphin's body temperature is very similar to ours - about 98 degrees. But dolphins have a layer of blubber to keep them warm.

    Where Do Dolphins Live?

    Dolphins live around the world in a wide range of habitats, from coastal to pelagic waters.

    What Do Dolphins Eat?

    Dolphins eat mostly fish and squid, although larger animals like orcas may eat pinnipeds and even other whales. Even though they have teeth, they do not chew their food like we do; instead, they swallow it whole (killer whales may also use their teeth to tear their prey into smaller pieces before swallowing.)

    Like other toothed whales, dolphins have the ability to use echolocation to find their food. This echolocation is conducted with the help of fatty tissue in the dolphin's forehead called the melon.

    Dolphins and Conservation

    Dolphins have long been captured for display in marine parks and aquariums. The first bottlenose dolphin was put on display in 1913. They are also used in captivity for research, to help scientists learn more about marine mammals and gain insights into human health.

    In the wild, dolphins may be threatened by getting caught as bycatch or entangled in fishing gear, habitat loss, and hunting, in some areas (such as the dolphin drive in Taiji, Japan, made famous by the movie .)

    Types of Dolphins

    One of the most famous dolphin species is the bottlenose dolphin. Below is a list of all dolphin species, provided by the International Whaling Commission. As you can see, there are plenty of different species that may look similar but have distinctive differences.

    • Common bottlenose dolphin

    • Indo-Pacific bottlenose dolphin

    • Atlantic spotted dolphin

    • Pantropical spotted dolphin

    • Spinner dolphin

    • Clymene dolphin

    • Striped dolphin

    • Common dolphin

    • Long-beaked dommon dolphin

    • Fraser's dolphin

    • Northern right whale dolphin

    • Southern right whale dolphin

    • Commerson's dolphin

    • Chilean dolphin

    • Heaviside's dolphin

    • Hector's dolphin

    • Melon-headed whale

    • Pygmy killer whale

    • False killer whale
    • Killer whale
    • Long-finned pilot whale
    • Short-finned pilot whale
    • Irrawaddy dolphin
    • Australian snubfin dolphin

    Where to See Dolphins

    You may visit captive dolphins in some marine parks (e.g., SeaWorld) and aquariums and even swim with dolphins, but it's often even more fun and exciting to see dolphins in the wild. Many places offer whale and dolphin watching tours, and in some places, such as the southeastern U.S., you can even see dolphins from shore.

    (I Monkey Mia, Australia, the dolphins may even come to you.)