Phocoena
A genus of PORPOISES, in the family Phocoenidae, comprised of several species. They frequent coastal waters, bays, estuaries, and the mouths of large rivers.
Porpoises
Mammals of the family Phocoenidae comprising four genera found in the North Pacific Ocean and both sides of the North Atlantic Ocean and in various other seas. They differ from DOLPHINS in that porpoises have a blunt snout and a rather stocky body while dolphins have a beak-like snout and a slender, streamlined body. They usually travel in small groups. (From Walker's Mammals of the World, 5th ed, pp1003-4)
North Sea
Dolphins
Mammals of the families Delphinidae (ocean dolphins), Iniidae, Lipotidae, Pontoporiidae, and Platanistidae (all river dolphins). Among the most well-known species are the BOTTLE-NOSED DOLPHIN and the KILLER WHALE (a dolphin). The common name dolphin is applied to small cetaceans having a beaklike snout and a slender, streamlined body, whereas PORPOISES are small cetaceans with a blunt snout and rather stocky body. (From Walker's Mammals of the World, 5th ed, pp978-9)
Echolocation
Cetacea
An order of wholly aquatic MAMMALS occurring in all the OCEANS and adjoining seas of the world, as well as in certain river systems. They feed generally on FISHES, cephalopods, and crustaceans. Most are gregarious and most have a relatively long period of parental care and maturation. Included are DOLPHINS; PORPOISES; and WHALES. (From Walker's Mammals of the World, 5th ed, pp969-70)