The short-beaked common dolphin was first thought to be the only species of the genus, Delphinus. But soon, studies show that there is another species, the long-beaked common dolphin ("Delphinus capensis"). The difference between the short-beaked common dolphin and the long-beaked common dolphin is that the short-beaked common dolphin is smaller in size and has a smaller beak than the long-beaked common dolphin.