People have long been fascinated with those playful and intelligent sea creatures we call “dolphins” and “porpoises.” Although some people think dolphins and porpoises are basically the same, you might be surprised to learn they are quite different creatures.

If you haven’t seen them nose to nose, then it can be difficult to tell the difference between dolphins and porpoises. This is because they can look quite similar, and they do share many characteristics.

For example, both dolphins and porpoises are mammals. Although they both live in the ocean, neither dolphins nor porpoises are fish!

Like all mammals, they have lungs instead of gills, so they breathe air. They also give birth to live young and nurse them after they’re born.

Porpoises and dolphins are both members of the same scientific order, Cetacea. Cetacea includes all whales, which are relatives of dolphins and porpoises.

Dolphins and porpoises are also both members of the same scientific suborder, Odontoceti, which includes all of the toothed whales. All members of Odontoceti can also “echolocate,” which means detect objects around them using sound echoes.

Porpoises and dolphins part ways at the level of scientific family, though. Porpoises are part of the scientific family Phocoenidae, while dolphins are part of the Delphinidae family. When you concentrate on the differences at the family level, dolphins and porpoises can seem quite different.

There are definite, yet subtle physical differences between the two aquatic mammals. Porpoises tend to be smaller than dolphins.

While dolphins can be 10 feet long (or longer!), porpoises are rarely longer than 7 feet. Dolphins also tend to be leaner and sleeker, while porpoises are more compact and often look chubby in comparison.

Dolphins usually have beak-like, pointed snouts, while porpoises have blunt, rounded noses. Porpoises have triangular dorsal fins, like a shark. Dolphins, on the other hand, have dorsal fins that are more curved like a wave.

The teeth of the two animals offer an easy way to tell them apart. Porpoise teeth are flat and rectangular. Dolphin teeth are cone-shaped.

While the physical differences between dolphins and porpoises can be subtle, the differences in the way they behave are more obvious. Dolphins live in large groups and show little fear of humans. They are outgoing and will often interact with humans and even swim alongside boats.

Porpoises, on the other hand, live in small pods of two to four animals and are quite shy. They rarely approach boats or people. In fact, you rarely see them at the surface unless they’re coming up to breathe. If you’ve ever seen an animal at a marine show, it was almost certainly a dolphin, not a porpoise.

The life expectancy of dolphins and porpoises is also quite different. While most porpoises only live 15 to 20 years, dolphins can live up to 50 years or more. Scientists believe this difference may be caused by the fact that porpoises reproduce faster than dolphins and it takes a toll on their bodies.

One last difference to note is that dolphins produce sounds that humans can hear. Many people have seen firsthand how “talkative” dolphins can be. Porpoises, on the other hand, make sounds that humans cannot hear.


23 Join the Discussion

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    • WOW! You are lucky to have been able to spend time with a dolphin up close, Megan! Thank you for sharing your personal connection to this Wonder of the Day®! :-)

    • Hi there, B.G.! Thanks for stopping by this Wonder and also for letting us know you love dolphins! Be on the lookout for a future Wonder of the Day® about giraffes, OK? :-)

  1. I am in Cape May I saw dolphin everywhere. One year ago I went on a ship, the guy said if a dolphin stares at you it likes you. It stared at me.

    • What a REALLY cool experience with a dolphin, Julia! Thank you for sharing your personal connection to this Wonder of the Day®! :-)

    • Great question, Wonder Friend L! We hope you enjoyed WONDERing with us about these two mammals! We will give you a clue: the two animals are different when it comes to size and how they live. We Wonder if you can go back to the article and find what those differences are! Keep up the SUPER work, Wonder Friend L! :)

    • Hi there, Charlie! We are so glad you learned something new about the difference between dolphins and porpoises! They are similar in many ways, but they are very different in size! :)

      • Charlie, A dolphin is a mammal. Mahi Mahi is a fish called the dolphin fish. What you eat in a restaurant is not the mammal, that would be illegal. We are indeed seeing dolphins, the mammal, as we rarely see the porpoise.

    • WOW, how neat, Rebecca! That sounds like a totally zoo-tacular experience! Thanks for telling us about your connection to this Wonder. We wonder what the giraffes ate? :)

  2. We live in LLANDUDNO North Wales just today we saw either dolphins/ porpoises jumping out of the water ,is it possible to say which they are as dolphins are not normally seen this far up in the UK ?

    • Hey there, Barbara, thanks so much for WONDERing with us today! We are so glad you shared your comment – what WONDERful news to meet a new friend living in North Wales! We wish we were there to see the awesome dolphin or porpoise with you, but we don’t know for sure which creature it was. Perhaps you can do some research of your own with the help of your local library! :)

  3. I work with dolphins and it is so cool to see them each day. I love to do shows with them. It is amazing how much they love humans!!!!!!!!!!!!!

    • How WONDERful, Smiley! We think that is awesome that you get to work with dolphins! We’re sure that there are many members of our community that would like to learn more about your work. Thanks for sharing! :-)

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Have you ever wondered…

  • What’s the difference between dolphins and porpoises?
  • Are dolphins and porpoises fish?
  • Are dolphins or porpoises more likely to be the stars of marine shows?

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Try It Out

One of the ways humans know dolphins are quite intelligent is how they use sounds to communicate with each other. Using a wide variety of whistles, clicks and chirps, dolphins can communicate with other dolphins in their group, as well as other types of dolphins they come across in the oceans.

Explore the world of dolphin communication by listening to recordings of incredible dolphin sounds! What do you think each sound is trying to communicate?

If you’re interested in dolphin communication, you can also check out these interesting videos:


Still Wondering

Listen to Science NetLinks’ Dolphin Brains audio podcast to meet a scientist who is trying to find out how dolphins got so brainy.


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