"The name derives from French pourpois, originally from Medieval Latin porcopiscus (porcus pig + piscus fish)."
"Porpoises, divided into six species, live in all oceans, mostly near the shore. Freshwater populations of the Finless Porpoise also exist. Probably the best known species is the Harbour Porpoise, which can be found across the Northern Hemisphere. Like all toothed whales, porpoises are predators, using sounds (echolocation in sonar form) to locate prey and to coordinate with others. They hunt fish, squid, and crustaceans."
Published under CC-BY-SA license from Porpoise at Wikipedia.