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Differences Between Whales, Dolphins, and Porpoises

When I was a child back in the 70's, my family and I watched Jacques Cousteau as often as possible. It was through his adventures that I first heard the sound of a Humpback whale singing, and when I first fell in love with dolphins. Or was it porpoises? I'm not exactly sure, because like quite a few folks, I was never clear on whether they were a different animal or the same. Whales-no problem! Killer whales were whales, right?

Most of the ocean life on the program gathered their oxygen from the water, but these animals that so fascinated me were mammals, like us. They bear live young, they nurse their babies, they breath air. They are the Cetaceans, otherwise known as whales, dolphins and porpoises.

Resembling each other in many ways, it is easy to confuse one with the other, especially between dolphins and porpoises, as was my problem for years. Adding to the confusion are fish called dolphins and dolphins that are called whales. And to make matters even more confusing, dolphins and porpoises are smaller members of the toothed whale family (as oppose to baleen whales).

So what are the differences? Are dolphins porpoises and can a whale be a dolphin? Or is it the other way around?

How can you tell a whale from the other two Cetaceans? Whales tend to be larger, ranging from 25 to 100 feet for the largest species, and around 9 feet for the tiny Dwarf Sperm whale. Another notable difference is baleen, a comb-like row that lines the upper mouth of some whales in place of teeth. Ocean water filters through the baleen, straining out small animals such as krill and crustaceans for food. Whales also have the longest lifespan of any of the Cetaceans. There is still much debate over the span of years, but typically quoted by marine experts is somewhere between 25 and 90 years. Whales also put on a display called breaching, when they shoot out of the water as fast as possible, landing on their side or back with a tremendous splash.

Dolphins are the medium size Cetaceans, ranging from 7 feet to 12 feet in length. The largest dolphin is the Killer Whale. There are over 30 species of dolphin including the Bottlenose, Risso, and Pilot Whale. A separate group is called river dolphins. They live in fresh water and are the smallest and very rare. There are only 4 species of river dolphins, with the strong possibility that one of those is now extinct. Unlike whales and porpoises, dolphins have what is called a beak jutting out like a nose on the front of their face, and their dorsal fin tends to be larger, and hooked or curved in shape. Dolphins form large complex social groups and are more prone to play near the surface, leaping and bounding for sheer enjoyment. They can live up to 50 years.

Porpoises are much smaller and shyer than dolphins. Common species include the Harbor and Dall's porpoise. They typically range in size from only 4 to 7 feet, and their lifespan barely reaches the mid teens. Porpoise's social groups are much smaller and simpler than Dolphins, and because they are so shy, it is rare to see them play. They have rounded heads, no beak, and a small, triangular dorsal fin. Even their teeth are a different shape, spade-like instead of a dull point.

So there are differences between Cetaceans; some obvious, some not so obvious. I now know that Killer whales are actually dolphins, and porpoises are themselves. But what about Belugas and Narwhals?

Learn more about this author, Lynn Schwalbe-Larson.
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