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  The Mammals of Texas - Online Edition

Atlantic Spotted Dolphin
Order Cetacea : Family Delphinidae : Stenella frontalis (Cuvier)

Atlantic Spotted Dolphin (Stenella frontalis).  Illustration by Pieter A. Folkens.Description. A rather small, long-snouted, spotted dolphin; ground color purplish gray, appearing blackish at a distance, usually with numerous small white or gray spots on sides and back; sides paler, belly whitish; young grayish, unspotted; dorsal fin high and strongly recurved, strongly concave at rear; beak deeper than wide and about 6% of total length of animal; teeth small and slightly incurved, especially toward tip of snout in upper jaw, varying in number from 31/31 to 37/34; height of teeth above jawbones seldom over 10 mm; diameters of largest tooth at alveolus, 5.5 by 4.0 mm; total length, 2.2 m; girth in front of dorsal fin, 1.2 m; length of anterior edge of dorsal fin, 431 mm; width of flukes, 661 mm. Weight, 125 kg.

Distribution in Texas. These dolphins are a common, offshore resident of tropical and warm temperate waters of the Atlantic Ocean. Not known outside of the Atlantic. In the Gulf of Mexico, this dolphin is second in abundance only to the bottlenose dolphin, Tursiops truncatus.

Habits. Atlantic spotted dolphins may be seen in groups of up to 50 animals, but smaller groups of six to 10 are more common. They eat small fishes including herring, anchovies, and flounder, as well as squid.

These dolphins make a variety of sounds used in echolocation and communication. Sounds are described as "loud whistles, chirps, low intensity click trains, squawks, barks, growls, and cracks."

These dolphins mate and calve in summer. Sexual behavior has been observed in the Gulf of Mexico in mid-May. The gestation period lasts 12 months and calves are born in offshore waters.

Although this dolphin is a common offshore resident of the Gulf of Mexico, the dolphins may move into nearshore waters in late spring and summer in Florida. This movement may be related to the movements of certain prey species for the dolphins; such migrations are not known for Texas waters.

Remarks. This dolphin was previously known as Stenella plagiodon.

Illustration credit: Pieter A. Folkens.