Body to approximately 5.6 feet (1.7 m) long. Body steel blue to dark brown on back; white on belly. Dorsal fin nearly triangular; curves only slightly backward. Distribution in Lake Maracaibo and the rivers of Guiana and in the nearshore coastal waters of northeastern portion of South America.
Body to about 8 feet (2.4 m) long. Body dark gray to purplish gray on back with white or pink blotches on sides; belly white. Body frequently shows numerous white scars. Head tapers gradually; beak long and slender; no clear separation of beak from forehead. May ride bow waves. Distribution in deep tropical waters.
Body to 8-9 feet (2.4-2.7 m) long. Body black with white belly patch which may extend up sides in area of anus. Head rounded; no beak; lips white; lower jaw and chin may be white. Dorsal fin to 15 inches (38 cm) tall, falcate; located near midpoint of back. Distribution tropical and subtropical.
Body to about 9 feet (2.7 m) long. Body black on back; light gray on belly. Head rounded; no beak; underslung jaw; lips white. Dorsal fin to 10 inches (25.4 cm), tall, distinctly back curved. Distribution tropical (not yet reported in western North Atlantic).
Body to about 11 feet (3.4 m) long. Body dark steel gray on back; lighter gray on sides; pinkish to white on belly (older animals speckled on belly). Head blunt; jaw underslung; false gills or bracket marks on side of head. Dorsal fin small; located in last one-third of body. Has not been reported to ride bow waves. Distribution in tropical and temperate waters.
Body to about 9 feet (2.7 m) long. Body dark steel gray on back; lighter gray on sides; pinkish to white on belly. Head blunt; jaw underslung; false gills or bracket marks on side of head. Body has two small creases on throat. Dorsal fin like that of Atlantic bottlenosed dolphin; located near midpoint of back. Has not been reported to ride bow waves. Distribution poorly known; at least from Georgia to the tropical seas.
Body to 5 feet (1.5 m) long. Body dark brown above and white below; transition zone on sides often speckled or streaked; ventral white extends high onto side in front of dorsal fin. Head rounded; beak small and indistinct. Dorsal fin short and triangular. Distribution in shallow waters from at least Delaware north; generally found inshore; often in bays, river mouths and inlets. Does not approach boats.