Much of what we know about Risso's dolphin, also called grampus, comes from studying stranded animals. They inhabit deep tropical and warm-temperate waters worldwide, usually where the water is deeper than 180 m, making them hard to study. Learn more about the Grampus griseus, more commonly known as a Risso's Dolphin, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.