This article is from the Dolphin
FAQ, by Jaap van der Toorn
Dolphins and porpoises belong to different whale families. The most obvious differences are:
- dolphins have a falcate (hook-shaped) dorsal fin, whereas porpoises have a triangular dorsal fin.
- dolphins have conical teeth; the teeth of of porpoises are spatula shaped.
- most dolphin species have a distinct beak. Porpoises don't, giving their head a more rounded, blunt shape.