The Real Difference Between Dolphins and Porpoises

The difference between dolphins and porpoises lies in the teeth.

Ask someone about the difference between a dolphin and a porpoise and they may point to the two species closest to us here in Sacramento. The San Francisco Bay is home to both bottlenose dolphins (Turciops truncatus, above) and harbor porpoises (Phoecoena phoecoena). Looking at them, you notice that our local dolphin has a long beak, and the harbor porpoise does not. Is the identification problem solved? Not so fast, Junior Ranger, because the real solution belongs to dentistry, and here’s why.

The harbor porpoise is the closest type of porpoise to Carmichael.

Harbor porpoise (Phocoena phocoena)

The Curious Counterexamples

There are other local dolphins with long beaks, like the common dolphin (Delphinus delphis). Search a little more, however, and you also find dolphins in our area with no beak at all, such as Risso’s dolphin (Grampus griseus) and the Pacific white-sided dolphin (Lagenorhynchus obliquidens). If you judge a dolphin only by its beak, you miss these counterexamples, identified by zoologists as dolphins.

As for porpoises, the Dall’s porpoise (Phocoenoides dalliis) is also seen in our Pacific waters and likewise has no beak. The vaquita (Phoecoena sinus) of the Gulf of California, between Baja California and the rest of Mexico, is also a porpoise without a beak. Yet, there are examples of a porpoise with a very long beak, such as the extinct species Semirostrum ceruttii, known only from fossils.

The killer whale has teeth shaped for eating fish.

Killer whale (Orca orcinus) with conical teeth.

It’s the Teeth!

The key to identifying a porpoise or a dolphin actually lies with its teeth. Admittedly, it’s hard to ask cetaceans to open their mouths wide while we sail off our shores. When examined close-up, however, the teeth of a dolphin are shaped like cones, with a wide base and narrow top (think killer whale, Orcinus orca, the big member of the dolphin family). The teeth of the porpoise are spade-shaped, since they look like little shovels, with a narrow base and wider top (see image below).

Why Is It Important?

In the grand scheme of things, dentists can take care of human teeth without knowing anything about porpoises or dolphins. But dentists tend to be curious about all things involving dentition, whether human or animal. We study animal teeth to learn things about repairing enamel and improving tooth durability for humans. And sometimes we do it just because it’s interesting!

Like humans, porpoises have teeth made of enamel.

The spade-shaped teeth from a porpoise jawbone.

We hope our clients here in Carmichael feel the same way. The more interest you have in teeth, the better care you tend to give them. Our dental team is here to help you in that goal.

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Comments
  1. When I was growing up, my brothers chewed ice what seemed like all the time. I’m so glad I found it a grating habit and never started it too! Why do people who may have an iron deficiency want to chew ice though?

  2. This is a great question. One of more common side effects of anemia is glossitis or inflammation and depapillation of the tongue. It causes soreness of the tongue and chewing ice is very soothing to these individuals. Pica is the term used in medicine that describes craving and chewing substances that have no nutritional value, such as ice, paper, cornstarch, etc.
    The other common cause of pica is emotional problems, such as stress. Thank you for your question and I too am glad that you did not pick up the habit.

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