Alligator mississippiensis
Recently on our trip to the I’On Swamp area of the Francis Marion National Forest, we observed an alligator resting on the banks for about five minutes before it plunged into the black waters of the swamp. The alligator species found in South Carolina is the Alligator mississippiensis. There are only two species of alligator, the American and the Chinese alligator. Before doing this research I was unaware that the alligator is only native to the United States and China. In the U.S. they only inhabit the 8 southeastern states and two more in the western part of the country. Alligators can be easily distinguished from crocodiles because of their large, broad snout with upward facing nostrils at the end allowing them breathe while the rest of the body is underwater. This is opposed to the V-shaped snout of the crocodile. Alligators also lack the protruding tooth of the lower jaw seen in crocodiles. Their clawed, slightly webbed feet and muscular, flat tail aid in propelling them in the water. While they appear to be very slow moving on land, they capable of running fast in short bursts. The crocodilian family, to which alligators belong, is the most vocal of all reptiles. They use their calls to defend territories, initiate courtship and when implementing parental care. During courtship in the spring time alligators may produce loud bellows to attract mates. These calls are often done in chorus. Male alligators may also use the hota posture, where both their head and tail are slightly above the water as they make a bellowing sound. This causes the water on their backs to vibrate and jump. .It is often called a water dance. Once copulation and gestation has occurred the female lays her eggs in a nest. While alligators are solitary animals, they do provide extensive parental care to their young. Clutch sizes range between twenty and fifty but few offspring survive. Sex determination is temperature dependent, with warmer temperatures yielding males. Once female’s eggs are ready to hatch, the young alligators release a distress call signaling her that they are ready to hatch. The mother may then assist her young in getting out of their shells by holding them in her mouth gently, helping to crack the egg further. Once hatched the young continue to give off contact calls, to stay in close range of their mother and other siblings. When threatened they may give off distress calls that signal the mother to defend her young. Young can easily be distinguished from adults by the bright yellow stripes on the tail, compared to the dark stripes on the adult tail. They have an average life expectancy of about fifty years. For a short period of time the American alligator was placed on the endangered species list due to extensive hunting to acquire their skins. In 1987, within twenty years the alligator was removed from the list and are now considered to be only a threatened species. Today Florida and Louisiana are said to have the largest populations of the American alligator.
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1 comment:
I had no idea their clutches were so large. Why is egg/juvenile survival so low?
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