American alligator

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American alligator

Alligator mississippiensis is in the family Crocodylidae.  This family has existed since the upper Triassic period, but the modern family members appear in the fossil record as little as 80 million years ago.  There are three subfamilies, Alligatorinae, Crocodylinae, and Gavaialinae.  Some people also include a fourth subfamily, Tomistominae, which contains a single species, the False Gharial.  Alligatorinae includes the American and Chinese alligators and the caimans.  Crocodylinae includes the crocodiles. Gavaialinae contains the gharials (or gavials).  The alligators are unusually tolerant of cold and have been found frozen in ice at the most northern parts of their ranges (Beck).  
All of the family Crocodylidae is endangered.  However, the American alligator has undergone a dramatic population resurgence because of human protection.  Restrictions are still in place on capturing alligators from the wild (Beck).  Studies have shown that using hormones such as norethindrone can be used to feminize alligator embryos at the male producing temperature (Lance, 79).  This could lead to a way to help alligators increase in numbers of both sexes as well as help other members of the family Crocodylidae.  Alligators are important ecologically and are dependent on the spatial and temporal patterns of water fluctuations.  Patterns of courtship, mating, nesting, and habitat use are all dependent on marsh water levels.  Alligators are a great study organism to study the adaptations and responses to the seasonal changes to the hydrological conditions in the everglades.  Alligators seem to be able to adjust the height of the nest egg cavity based on the spring water levels, which historically indicated the water levels later in the nesting season.  Water levels also determine the availability of food therefore affecting the patterns of growth and survival.  Alligators are most abundant in central sloughs, which is probably due to recommendations regarding managing hydrological conditions for alligators focused on maintaining alligators in central slough habitats (Mazzotti, 485).
The American alligator is one of the keystone species in the Florida everglades and other marsh systems.  It is the only large, abundant, widespread nonmarine carnivore left in the southeastern United States (Mazzotti, 485).  They are spread as far west as reserves in Texas, and their northern boundary is in South Carolina.
The interesting thing about alligators is the temperature determination of sex.  At 29C all females will be produced.  At 32C all males are produced. Temperatures in-between will produce mixed sets of young.  The lower the temperature the less yolk there is for the young, there fore the young turns out smaller and female (Allsteadt, 76).  It would be the opposite for warmer temperatures.  The female alligator chooses the nest site, which in turn determines the sex of the young.  The sex of the young is determined in the first two-thirds of incubation.  During the final third of incubation the quality of the young is determined.  Snout length, carcass lean dry and lipid mass, and yolk sac lean dry and lipid mass are determined by the final third of the incubation period (Congdon, 497).  These characteristics could affect the vitality of the young in competition after they hatch.  In South Carolina growth rates of alligators were thought to be slower, but it seems that alligators reach sexual maturity at a later age and larger body size than alligators elsewhere.  It is assumed that the delayed breeding of alligators in South Carolina may be related more to social dominance than to growth rates.  It is essential that age and size relations need to be understood better if alligators are to be managed effectively (Wilkinson, 397).
All alligators, caimans, gavials, and crocodiles are carnivorous.  In the wild, each depends upon a somewhat different selection of prey from its local fauna. For captive specimens, diet should vary with the size of the animal and the availability of prey.  Small captives will do well on small animals (e.g.. goldfish, insects, or mice.)  As the reptile grows, its diet should change from mice to rats to rabbits, chickens, and other suitable larger prey.  It's prudent to supplement meals with added calcium.
Reptiles are susceptible to a variety of cutaneous and deep mycotic infections, however relatively few cases are reported in the American