ATLANTIC SPOTTED DOLPHIN (T) 



SteneUaplagiodon (Cope 1866) 



Other Common Names 



Spotter, Gulf Stream spotted dolphin, spotted porpoise, 

 long-snouted dolphin." 



Description 



Atlantic spotted dolphins reach a maximum adult length 

 of 7.5, perhaps 8 feet (2.3 to2.4 m). They are generally more 

 robust in body shape than the other species of Stenella, 

 closely resembling Atlantic bottlenosed dolphins in that 

 regard, though the Atlantic spotted dolphins tend to be more 

 slender. 



The dorsal fin is distinctly back-curved and pointed on the 

 tip, also closely resembling that of the Atlantic bottlenosed 

 dolphin. 



As the common name suggests, the Atlantic spotted 

 dolphins are marked dorsally with numerous grayish-white 

 spots on a darker background and ventrally with dark spots 



' ' See also p. 110. The common name "long-snouted dolphin" was once 

 widely used for this species. It is now more frequently used for Stenella 

 longirostris. also known as the spinner dolphin. 



on a lighter background, though the extent of the spotting 

 and the additional details of coloration change with age. 



Immature animals lack spots completely. They are dark 

 gray or purplish gray on the back, becoming lighter gray on 

 the sides and white on the belly. The cape along the back is 

 distinctly separated from the lighter gray coloration of the 

 sides. The flippers and the trailing edge of the flukes are 

 darker than the rest of the body. 



As they age, the Atlantic spotted dolphins develop 

 grayish-white spots, first low on the sides, spreading 

 upward. During this stage, the cape becomes less distinct, 

 and dark spotting begins to develop on the belly, the spots 

 increasing in number with increasing age. In adult animals, 

 the belly is often extensively covered with dark blotches but 

 never becomes completely black. The lips may be white, and 

 the beak is characteristically tipped with white, a feature 

 which may aid in identification at sea. 



The Atlantic spotted dolphins have a spinal blaze and a 

 light line which extends from the flipper to the eye. 



Natural History Notes 



Little is known of the natural history of the Atlantic 

 spotted dolphins. The species occurs in herds of up to several 



Figure 115. — Atlantic spotted dolphins beside a research vessel off Beaufort, N.C., September 1965. Adults of this species can be identified by 

 the spotting pattern and the white coloration of the lips. (See also bridled dolphin, p. 108.) Young animals which lack spots may be confused 

 with the Atlantic bottlenosed dolphins though they are smaller and are purplish gray on the back. {Photo by G. T. Green.) 



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