Bridled dolphins have not yet been described from the South American coast.
Bridled dolphins have from 29 to 34 teeth in each upper jaw and from 33 to 36 in each lower jaw. They can be distinguished from spinner dolphins, which have 46-65 teeth in each jaw, by this character alone.
They may be distinguished from spotted dolphins only if the color pattern of the head is clearly visible. If it has faded, the specimen will probably require museum preparation and examination before it can be positively identified.
[Illustration: Figure 120.--A bridled dolphin harpooned in the commercial whale fishery off St. Vincent, Lesser Antilles. If the color pattern has faded, bridled dolphins cannot be readily distinguished from the Atlantic spotted dolphins and must be sent to a museum for preparation and examination of the skull and skeleton. (_Photo by W. A. Huck, courtesy of Marineland of Florida._)]
[Illustration: Figure 121.--A bridled dolphin from St. Vincent, Lesser Antilles. Note the dark cape of the back, the lighter side, and the dark stripes from the eye to the snout (found in most dolphin species) and the flipper to the gape, a feature which fades as the animal's spotting increases. Together these two features comprise the "bridle" from which the common name derives. Note also the white lips and the white lower jaw. (_Photo by J. R. Sullivan._)]
Long-snouted dolphin, long-beaked porpoise, spinner porpoise, rollover (St. Vincent).
Spinner dolphins reach a maximum length of about 7 feet (2.1 m). The body is slender. The beak varies from extremely long and slender (Fig. 123) to relatively short (Fig. 125); the beak is usually dark on top and clean white below, though there may be some white above. The tip of the snout and the lips are distinctly black, while those of both species of spotted dolphins are light. The back is dark gray to black, the sides are tan to yellowish brown, and the belly is white. Some of the larger animals appear almost all black with faint, light speckling. The dorsal fin is generally moderately falcate, but may be almost triangular in adult males. It is often a lighter gray near the middle, bordered by black or dark gray.
Spinner dolphins derive their common name from their habit of leaping clear of the water and spinning on their longitudinal axis. The reasons for this behavior are unknown. Individuals may rotate 2 times, or more, in one leap but spinning behavior is not observed as frequently in the western North Atlantic as it is in the eastern tropical Pacific.