Alligators and crocodiles are easily confused with each other. Both are large - often very large - toothy, heavily-armoured, amphibious reptiles that can really take the fun out of a wild swim.
But crocs and gators are not the same, belonging to different families that went their separate ways about 90 million years ago.
Members of the crocodile lineage tend to have narrower, pointier snouts than alligators, and their infamous smiles are toothier and more wavy. Alligators have a slight overbite, which obscures the lower teeth when the mouth is closed.
Colour-wise, most crocodiles are light greenish-brown, while alligators are usually darker and greyer. The scales of both groups are dotted with numerous dark pores that detect movements of the water and prey animals. These are distributed all over a crocodile’s body, but only around the mouth in alligators.
Another important difference is that crocodiles - but not alligators - can secrete excess salt from their body via glands on their tongue. This means they can tolerate brackish and marine habitats. Saltwater crocodiles, the largest of all living reptiles, exceeding 6m in length and a tonne in weight, are capable of making long journeys across the open ocean. Alligators, though, are restricted to freshwater habitats.
This is one reason why crocs and gators are rarely found together. Another is that the 18 species of crocodile are distributed throughout the world’s tropics, while alligators prefer more temperate climes. Only two species go by the name of alligator. One, the American alligator, is native to the south-eastern USA; the other, the critically endangered Chinese alligator, occupies an area of just five square km on the Yangtze River. The nearest crocodiles are more than 1,000km further south.
Can crocodiles and alligators co-exist?
There is one place where crocodiles and alligators do live together. The southern tip of the US state of Florida sits on the southern edge of the American alligator’s range. But it also marks the northern edge of the range of the American crocodile, a species that occurs in the Caribbean and Central and South America. And the vast wetlands of the Florida Everglades contain the right mix of habitats to accommodate both.
While the alligators dominate the rivers, lakes and freshwater marshes, the crocodiles prosper in the coastal bays, brackish lagoons and estuarine mangrove forests.
For the most part, their habitat preferences keep them away from each other. However, the crocs are known to venture into the gators’ freshwater territories, and when that happens, things can get violent.
Top image: Florida Everglades. Credit: Tetra Images/Getty Images
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