Dolphins and porpoises are among the smartest and most beautiful creatures on the planet. And they’re also among the most popular. Even so, most of us can’t tell dolphins and porpoises apart. Yet there are several key differences, in both appearance and behavior.
Dolphins and porpoises are cetaceans -- a group of animals that also includes whales. There are 32 species of marine dolphins, but only a half-dozen species of porpoises. All of them are warm-blooded mammals that come to the surface to breathe air.
It’s said that sharks can smell a drop of blood in water a mile away. Depending on the shark species and its prey, that may be an exaggeration, but these predators undoubtedly have an incredible sense of smell. Some species can detect the scent of prey at one part per 10 billion — equivalent to a single drop in an Olympic size swimming pool. But sharks’ noses may do more than find food. For leopard sharks, at least, their sense of smell may also help them find their way.
