See a cetacean leaping into the sea, and you'll probably assume it's a dolphin.
But look a little closer — it could also be the less appreciated (but still just as smart and cool) porpoise. The two share a lot in common, but a deeper understanding of each animal can help you spot the small differences between the two types of cetaceans.
The first and most obvious difference between dolphins and porpoises is their face. Dolphins are known for their long, pointy beak-like noses.
If you get a glimpse inside that beak, you'll notice a mouthful of triangular-shaped teeth.
A porpoises face is a little different. It's more rounded, closer to what we think of as a whale's face.
Inside its mouth, porpoise teeth are shaped like spades.
Fins can be another main difference between the two.
Dolphin fins tend to have a bit of a hook or curve to it, while a porpoise's is smaller and more triangular. And while both are able to quickly swim throughout the sea, dolphins are known for doing so with a slimmer, sleeker body than the rounder porpoise's.
The two animals also have differences you can't spot just from looking at them.
For one, there is more variety among dolphins, since there are 32 different varieties of them compared to seven different types of porpoises.
Dolphins are also a lot more likely to grow old — they can live for more than 50 years, whereas most porpoises don't make it past 20.
For all their differences, though, the two animals still share many characteristics. They're both underwater mammals, and both are some of the most intelligent creatures in the ocean.