Some of the main differences between a dolphin and a porpoise can be noted by comparing their body shapes. When porpoises or dolphins strand on a beach, scientists are able to tell them apart by examining their teeth. At sea, their social groupings and behaviours also provide strong clues.
Dolphins typically travel in much larger groups and are far more likely to go bow-riding.
The six species of true porpoises live mainly close to shore, but many dolphins are real world citizens and can be found in several climatic regions in every part of the vast world ocean.