Everything about Phocoenidae totally explained
Porpoises are
small cetaceans of the
family Phocoenidae; they're related to
whales and
dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by
sailors and
fishermen. The most obvious visible difference between the two groups is that porpoises have flattened, spade-shaped
teeth distinct from the conical teeth of dolphins, and their shorter beaks.
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 to locate prey and to coordinate with others. They hunt fish, squid, and crustaceans.
Porpoises apparently diverged from dolphins about 15 million years ago in the northern Pacific, then spread across the globe much later.
Taxonomy and evolution
Porpoises, along with whales and dolphins, are descendants of land-living
ungulates (hoofed animals) that first entered the oceans around 50 million years ago. During the
Miocene (23 to 5
MYA), mammals were fairly modern. The cetaceans diversified, and fossil evidence suggests that porpoises diverged from dolphins and other cetaceans around 15 MYA. The oldest fossils are known from the shallow seas around the north Pacific, with animals spreading to the European coasts and southern hemisphere only much later, during the
Pliocene.
