Alligators and crocodiles have many similarities. They are both carnivores found near water. Most species are about the same size except for the Saltwater Crocodile, which can be two-thousand pounds in weight. Both of them are cold blooded and must regulate their body temperatures, either by being in water or basking in the sun. All have tongues attached to the bottom of the mouth, preventing the tongue from moving. One striking similarity is the lack of sex chromosomes; the youngs' sex is determined by the temperature at which the eggs are incubated; males are incubated at a slightly higher temperature than the females (MacMillan 5). With all these similarities, it can be concluded that they share a common ancestry. Both alligators and crocodiles belong to the order crocodylia.
Despite all the similarities, there are differences in the two animals. Alligators have a wide, rounded snout, and crocodiles have a longer, pointed snout. The fourth tooth in the lower jaw of the crocdile is visible when the mouth is closed, unlike the alligator, whose upper jaw hides the tooth Crocodiles have functioning salt water glands on their tongues, whereas alligators have the gland, but it doesn't function to excrete excessive amounts of salt. Crocodiles need such glands for their salt water environment, and alligators prefer fresh water. Crocodiles tend to be grayish in color, and alligators tend to be greener. Aditionally, alligators mature in four to seven years, and crocodiles mature in eleven years. Although similar in appearance, these are two distinct species.
For alligators and crocodiles, the differences in appearance are all in the fine details of shape, size, and color. They share a common ancestor, but evolution has given each species its unique characteristics and behavioral role. Both species are fighting the same battle of survival against humans. So far, they are on the losing side. Hopefully through conservation, we'll have these prehistoric creatures for many more centuries.