People use the term dolphin, porpoise and whale to describe marine mammals belonging to the order Cetacean (from the Greek work ketos, “large sea creature”), and often use them incorrectly. Whales (Cetacean) are divided into two group’s baleen whales (Mysticeti) toothed whales (Odontoceti). The main difference between them is that baleen whales have baleen and two blow holes while toothed whales have teeth and one blow hole.
Dolphins are toothed whales and the largest dolphin is the Orca (generally mistaken for a whale due to its name killer whale). A related family to dolphins are Porpoises. People often confuse dolphins and porpoises, but there are differences to look out for e.g. their faces, teeth, fins and figures. Dolphins tend to have prominent, elongated “beaks” and cone-shaped teeth, while porpoises have smaller mouths and spade-shaped teeth. The dolphin’s hooked or curved dorsal fin (the one in the middle of the animal’s back) also differs from the porpoise’s triangular dorsal fin. A dolphin’s body is lean and a porpoises’ body is rounded.
Dolphins are also more talkative than porpoises. Dolphins make whistling sounds through their blowholes to communicate with one another underwater. Scientists are pretty sure that porpoises do not do this, and some think this may be due to structural differences in the porpoise’s blowhole.
As all animals differ both in looks and genetics so do whales, dolphins and porpoises. It’s not easy to know what is what in the cetacean world, but remember: all dolphins are whales, but not all whales are dolphins.