|The Mammals of Texas -
Atlantic Spotted Dolphin
Cetacea : Family Delphinidae : Stenella
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
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