dolphins vs. porpoises: what’s the difference?

Marine mammals like dolphins and porpoises are fascinating, intelligent creatures. However, the two species are often confused with each other, and the names are mistakenly interchanged. So, what exactly is the difference between a dolphin and a porpoise, and how are they similar?

is a dolphin a porpoise?

No. Dolphins are not types of porpoises, porpoises are not types of dolphins, and they are not different names for the same thing. They are separate sets of animals, each including multiple species.

Did you know: We also often get asked, “Are dolphins whales?” The answer is yes, but it gets a bit complicated. Larger whales like blue whales and humpbacks are classified as baleen whales. Dolphins and porpoises, on the other hand, are classified as toothed whales.

how are dolphins and porpoises similar?

To understand how dolphins and porpoises are related, consider where they fit in the tree of life. About 50 million years ago, some deer-like animals broke off from their land-dwelling ancestors, returning to the water and developing fins. These animals became Cetacea—the scientific term for the group that contains whales, dolphins and porpoises. To get even more specific, dolphins and porpoises are members of the toothed whale suborder called Odontoceti. 

Both dolphins and porpoises are sleek, intelligent, fully aquatic mammals that are highly social, living in pods and traveling with other members of their own species. They also both use sonar—or echolocation—to navigate under water and hunt for prey like fish and squid.

what are the differences between dolphins and porpoises?

In general, dolphins are much bigger than porpoises. The largest member of the dolphin family is the orca, also known as the killer whale, weighing in at a whopping 3,000 to 12,000 pounds (1360 to 5400 kilograms) as adults. By contrast, porpoises are some of the smallest of all the toothed whales, with the smallest species being the vaquita at four to five feet (1.3 to 1.5 meters) in length and weighing up to 120 pounds (54 kilograms) as adults.

One of the easiest ways to tell a dolphin from a porpoise is by looking at their heads. Dolphins have a prominent beak, while porpoises have more rounded heads and lack a distinct beak. Dolphins also have hook-shaped dorsal fins, while porpoises have dorsal fins that are more triangular. 

The tooth shape of each species is also unique; dolphins have pointed, conical shaped teeth, while porpoises have teeth shaped like spades.

what do dolphins and porpoises eat?

Toothed whales, including dolphins and porpoises, are carnivores that hunt and feast on other sea creatures. Both dolphins and porpoises consume a variety of prey, with diets heavy in schooling fish like herring, sand lance, mackerel and squid.

Did you know: The world’s largest dolphin—the orca—is a powerful predator! Some ecotypes consume other marine mammals such as seals, some eat only fish and others eat sharks and rays.

what threats do dolphins and porpoises face?

Dolphins and porpoises face growing threats from human activities including entanglement in fishing gear, plastic and chemical pollution, habitat loss and climate change. Ocean noise pollution from commercial shipping and military sonar poses another serious threat to dolphins and porpoises, both of which rely heavily on sound. The noise reduces their ability to communicate, navigate and locate prey.

what is IFAW doing to help dolphins and porpoises? 

IFAW works tirelessly to help all types of animals, including cetaceans like dolphins and porpoises. Our marine mammal rescue program is a world-recognized leader in stranding response. Based on Cape Cod, Massachusetts, no location in the world sees more frequent mass strandings of dolphins. These events are a unique opportunity to not only rescue and provide cutting-edge veterinary care to these individual animals, but also drive constant innovation and groundbreaking research that is shared with collaborators around the world.  

From a focus on the welfare of individuals to the protection of entire species, our marine conservation program works to prevent entanglements in fishing gear, reduce collisions with high-speed ships and ocean noise pollution, and fight against climate change and its impacts on marine ecosystems.