Crucial Differences: Whales, Dolphins, and Porpoises | Captain John Whale Watching & Fishing Tours – Whale Watching In Plymouth

Many individuals who are fascinated with marine life have difficulty distinguishing between whales, dolphins, and porpoises. All are members of the taxonomic order Cetacea. The terms are inconsistently applied, but generally “dolphin” refers to cetaceans of the familes Delphinidae (ocean dolphins) and Platanistoidea (river dolphins), and “porpoise” refers to members of the family Phocoenidae. “Whale” is a catch-all term for all other cetaceans, including remaining members of the order Odontoceti (toothed whales), of which the dolphin and porpoise families are a part, and all Mysticeti, or baleen whales.


There are a number of significant differences between these three species that can help whale watchers distinguish between them.

Whales, Dolphins, and Porpoises

  • Size

The most noticeable difference between these three classifications is their size. If you see a cetacean that is greater than a dozen feet long, it is most likely a whale. Porpoises are smaller than most dolphin species.

  • Teeth

This may be more difficult for people on whale-watching or fishing excursions to notice from a distance, but the presence of teeth or baleen is the major taxonomical difference between cetaceans. Larger whales typically do not have teeth, but instead use fringed plates made of baleen that extend from their upper jaws to filter their food from the water they take in when their mouths are open. Smaller whales and dolphins have cone-shaped teeth, whereas porpoises feed using spade-shaped teeth that are designed to catch smaller fish.

Dolphins and Porpoises

  • Dorsal Fins

Dolphins have larger dorsal fins than porpoises do, and porpoises’ dorsal fins tend to be triangular, while dolphins’ dorsal fins are curved.

  • Rostrum

The rostrum, or snout, is more beak-like in dolphins, while porpoises tend to have a more nose-like rostrum.

  • Social Movements

It is common for participants on a whale watching cruise to see porpoises swimming or feeding in solitude or in small groups. Dolphins, on the other hand, almost always move in large and complex pods.

Atlantic Spotted Dolphin (Stenella frontalis)

The next time you are in Plymouth, Boston, or Cape Cod, explore the great Atlantic on one of Captain John’s whale watching tours or deep sea fishing excursions. We guarantee sightings on every whale watching tour! Call (508) 746-2646 to find out more!

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