People often get alligators and crocodiles mixed up and it can be hard to tell them apart. It’s easier when you see them together.
They are the same shape, but alligators have broader, shorter snouts than most crocodiles. Their skin is darker, too, and looks black when wet.
In many ways, alligators and crocodiles are alike. Still, there are differences.
Scientists separate them according to differences in their skulls, scales, and teeth.
The easiest way to tell one from the other is by looking at their jaws. When a crocodile’s jaws are closed, the big forth tooth on each side of the lower jaw fits into a special notch in the upper jaw. This gives the crocodile a toothy grin. An alligator’s fourth tooth fits into holes in the upper jaw and can’t be seen when its mouth is closed.
Another clue is how many lower teeth stick out when the reptile closes its mouth.
When an alligator’s mouth is closed, you can see only a few, if any, lower teeth. That is because the alligator’s lower teeth fit and close inside its upper teeth. On a crocodile, however, the upper and lower teeth are more or less in line. As a result, when a crocodile’s mouth is closed, its lower teeth do stay in view, especially the large tooth that’s fourth from the front on each side of its mouth. When an alligator’s mouth is closed, these large lower front teeth aren’t visible.
The crocodile’s skull and jaws are narrower than the alligator’s. When its jaws are shut, it has more teeth sticking out than an alligator does.
Another differences between crocodiles and alligators is their choice of homes. Many species of crocodiles live in salt water. On other hand, alligators are freshwater reptiles. They rarely swim into salt water.
The only area in the United States where both alligators and crocodiles live is the southern tip of Florida. The American crocodile lives in the United States, Central America, and South America.
The American crocodile is large. It probably grows to twenty feet in length.
You will probably never see a wild crocodile. They are rare and shy. Of the fifteen species of crocodiles in the world only three kinds have been known to kill people. They are the African Nile crocodile, the saltwater crocodile of Australia, and the mugger crocodile of Southeast Asia.
There are also differences in behavior and habitat, the type of area an animal naturally lives in. Although American crocodiles are shy animals, alligators are not. Alligators often have contact with people. When alligators become used to people, they lose fear of them. Fearless alligators can be very dangerous to people.
Alligators are not as active as crocodiles. In fact they appear to be slow, sleepy animals. They are usually seen floating quietly in the water or resting on a muddy shore.
The skulls tell the story. An alligator skull (left) shows a broad snout; a crocodile skull (right) has a narrow, pointed one. But the only place you’d find crocodiles and alligators actually living together is in southernmost part of Florida.