A fairly robust dolphin with a short, rounded snout, Peale's dolphin is greyish black above and mostly white below. A curved, light grey flank patch runs from behind the dorsal fin to the tail, while a second light grey patch on the chest runs from the eye to the middle of the body. This second patch is separated from the white belly by a well-defined black line, which loops above a small white patch in the 'armpit', under the flipper (2) (4) (5) (6). The flippers and dorsal fin are dark, and the dorsal fin is sickle-shaped, with a light grey trailing edge. The face, snout, melon and most of the chin are dark grey-black, which, together with the black line below the chest patch, readily distinguishes Peale's dolphin from similar species such as the dusky dolphin (Lagenorhynchus obscurus
). (2) (4) (6). Young Peale's dolphins are lighter grey than adults, with less clear definition between the chest and flank patches (2) (4).