Saturday, August 6, 2011

Life of Atlantic Spotted Dolphin

Life of Sea | Atlantic Spotted Dolphin (Stenella frontalis) | Atlantic spotted dolphins are found in the shallow waters over sand flats. They are known to live in a variety of locations including the oceans around the United States, Africa, Europe, the Bahamas, and the Gulf of Mexico. They have significantly increased in numbers in the Bahamas. There are now hundreds of them when only a couple of decades there were less than 100 there. It is estimated that there are more than 100,000 Atlantic spotted dolphins out there. Some of them that live along the Gulf of Mexico do migrate annually. Others tend to move long distances each day but not out of a need to follow a migration pattern.

Atlantic spotted dolphins have a moderately long, stocky beak, with a distinctive crease between the base of the beak and the melon. The dorsal fin is tall and falcate and the flippers are curved backwards. Juveniles are unspotted and look similar to Bottlenose dolphins, with their dark cape, spinal blaze, light gray sides and white belly. As the animals age, spots on both ventral and dorsal surfaces develop and some individuals become so heavily spotted that the underlying colour pattern becomes obscured. However, adults in some offshore and temperate populations may remain unspotted. 
There is much developmental variation in the colour pattern. Atlantic spotted dolphins begin life with unspotted background coloration. Young animals look much like slender Bottlenose dolphins, with a dark cape, light grey sides and spinal blaze (variable in its development), and white belly. Large spotting on both dorsal and ventral surfaces progresses as the animal ages; some individuals become so heavily spotted that the cape margin and spinal blaze are obscured. However, in some populations, adults are essentially unspotted (these are generally in offshore areas).

Atlantic spotted dolphins can be most easily confused with Bottlenose dolphins and sometimes with Pantropical spotted dolphins. The differences are in size and robustness, but may require a trained eye to distinguish in many sightings at sea. Heavy spotting is a good characteristic for Atlantic spotted dolphins. However, some may be nearly unspotted and some Bottlenose dolphins may have spotting and blotches on the belly and sides. Pantropical spotted dolphins also may be difficult to distinguish, but attention to body robustness, snout shape, and colour pattern differences will allow them to be separated. Only the coastal form of the Pantropical spotted dolphin is likely to appear very similar to the Atlantic spotted dolphin, but the former is only known from the eastern Pacific.

Atlantic spotted dolphins are usually in small to moderate groups, generally of fewer than 50 individuals. Coastal groups usually consist of 5 to 15 animals. Their main food sources include octopus and various types of small fish. Most of the time they will fish at night. They also tend to hunt in groups as they have a tactic that allows them to get their prey into a big circle. Then they are able to come at these schools of fish from all angles. 

Atlantic spotted dolphins are excellent when it comes to communication. They use a variety of loud clicks and whistles to talk with each other. They form groups of about 50 and they are also known to move around with other species of dolphins without any conflicts among them. There is a hierarchy among these dolphins that depends upon many factors including their size, age, and gender. They are extremely protective of their young and will help each other to care for them. They also tend to do their best to protect the pregnant females from enemies including sharks.

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