How can you tell if that fin bobbing up and down in the distance belongs to a dolphin or a porpoise?

From far away you can probably only see the fin, right? The Atlantic bottlenose dolphin will have a dorsal fin that is hooked while the Atlantic Harbor Porpoise will have a triangular dorsal fin. If you are closer you will see other differences. For instance, the dolphin is about 7-12 feet as an adult while the porpoise gets to be about six feet. Also, the porpoise has a rather blunt nose while the dolphin has a much more pronounced, almost bottle-shaped, nose. Lastly, the porpoise is usually darker in color than the dolphin. Do you have another great question? Check out www.beachchairscientist.com and let us know what you always ponder while digging your toes in the sand!