Is It a Dolphin or a Porpoise

At first glance, dolphins and porpoises look similar. Taking a closer look, there are some general differences that distinguish these animals. See the common bottlenose dolphin (left) and harbor porpoise (right) pictured above.

Dolphins and porpoises, along with whales, belong to a group of marine mammals called "cetaceans." Cetacean comes from the Latin word for "large sea creature." Dolphins and porpoises are further classified as toothed whales, or "odontocetes." They are highly intelligent animals that use echolocation to find food, communicate, and navigate. As with all marine mammals, they both come to the surface to breathe.

Although dolphins and porpoises are similar, they are not the same. There are some physical characteristics and behaviors you can look for to tell the difference between dolphins and porpoises.

How to Recognize a Dolphin

Dolphins typically have longer, leaner bodies than porpoises. They have hooked or curved (falcate) dorsal fins, resembling a sickle. Their faces have clearly defined, elongated "beaks," and their teeth are pointed and cone shaped.

Dolphins have long, lean bodies and hooked dorsal fins. Credit: NOAA Fisheries

Dolphins are "talkative," communicating with each other through sounds made through their blowholes. These include clicks, squeaks, buzzes, and whistles. Dolphins are highly social animals and may be seen in large groups known as pods. They are more curious around humans and may approach boats-but for your safety and theirs, you should remain at least 50 yards away.

Dolphin faces are characterized by their prominent, elongated beaks. They also have pointed, cone-shaped teeth. Credit: NOAA Fisheries

Dolphins are found in every ocean. There are more than 30 dolphin species, including the short-beaked common dolphin, one of the most abundant cetacean species in the world.

How to Recognize a Porpoise

Porpoises have smaller, more stout bodies compared with dolphins. They have triangular dorsal fins and short faces with rounded beaks. Their teeth are flat and spade shaped.

Porpoises, like this harbor porpoise, have short, round heads. Their mouths are smaller compared with dolphins. Credit: NOAA Fisheries

Porpoises can be very shy and tend to avoid boats. In general, they are less social and do not vocalize the way that dolphins do. Instead, they communicate using very high-pitched clicks that humans cannot hear. This may be due to structural differences in their blowholes that could have evolved to avoid predators.

Dorsal fin of a harbor porpoise. Porpoises have triangular dorsal fins. Credit: NOAA Fisheries.

There are fewer species of porpoises, and they have a narrower geographic range than dolphins. Porpoises typically live in colder coastal waters in the Atlantic and Pacific Oceans.

As with all other cetaceans, dolphins and porpoises are protected under the Marine Mammal Protection Act. Some are also listed under the Endangered Species Act. It is important to view these wild animals from a safe and respectful distance for their safety-and yours. If you see a sick or injured dolphin or porpoise, please call your nearest marine mammal rescue organization.