South Florida is amazing for so many reasons, but one of the most incredible things about this area that very few people talk about is... this is the ONLY place on the entire planet where alligators and crocodiles live together! Now, part of the reason for that is that the only other species of alligator is the Chinese alligator that lives in a very small range in the mountain ranges of Eastern China, but it's still incredible nonetheless.
Our two native crocodilians here in Florida are the American alligator (Alligator mississipensis) and the American crocodile (Crocodylus acutus). The alligators live throughout the Southeastern United States ranging from Texas to the Carolinas, and South Florida is the southernmost part of their range. Likely many South Floridians, the crocodiles are much less cold-tolerant; they range throughout Northern South America, both coasts of Central America and Mexico, several of the Caribbean islands, and South Florida is the very northernmost tip of their range. The Everglades and the Keys are the primary areas where the two species' ranges overlap.
On the Gulf Coast, the crocodiles' established breeding populations don't expand too far past the Naples area. However, our climate is warming, and several have been observed in and around Charlotte Harbor over the last decade, with one large male even making it as far north as Tarpon Springs. So it seems like the crocs are slowly but surely inching their way north. That means you'll definitely want to know how to tell them apart, because while becoming more common, crocodile sightings in our area are still extremely rare and you should: A. consider yourself lucky to see one in the area, and B. report your sighting (with photos to confirm, if possible!) so that conservation agencies can continue tracking this endangered, federally protected species.
The first major difference is their habitat. Alligators GENERALLY will be found in freshwater, and crocodiles GENERALLY will be found in brackish or saltwater. Now they both can break the rules on this one a little bit. Alligators definitely can go into marine habitats, but they're unable to osmoregulate (maintains the fluid balance and the concentration of electrolytes) well enough to deal with the salt. So if you're at the beach and see an alligator, it's not living there, it's likely just passing through. On the same note, nothing stops crocodiles from going into freshwater, they just tend to prefer the coastal, estuarine areas.
Second, the color difference is markedly different between these two animals. But let's first recognize that neither of these animals are green, it's not like in the cartoons at all. Crocodiles have a very beautiful tannish-gray color to them, while alligators are jet-black to help blend in with the darker, murkier water that they often live in. Alligators also can sometimes have faint yellowish colorations on their sides, but will lose those colors as they get older.
Third, the snout shape is a telling characteristic between these two species. Alligators have a very broad, rounded snout shaped like the letter "U". Crocodiles, on the other hand, have a very narrow pointed snout shaped like the letter "V". In fact, their scientific name "acutus" comes from a Latin word for "sharpened" because of the way this species' snout comes to such a fine point.
Fourth, and this one is generally true but can differ for individuals, is their teeth. With their mouth closed, alligators will have an overbite and only their top teeth will be showing. Crocodiles also have an overbite, but a couple of the bottom teeth on each side will stick out as well when the mouth is closed. Now, these animals are strong predators that eat strong, tough prey, meaning their teeth are constantly breaking and falling out with a new one growing in to replace it. It's estimated that one adult alligator can go through over 3,000 teeth in a lifetime. So this rule about the difference in their teeth is generally true, BUT an individual can have a snaggle tooth or be missing teeth, so it's not the best rule to use to make your identification.
Finally the last difference, is what you would say to them when you are leaving. To an alligator, you'd say, "See you later", but you would tell a crocodile, "In a while!"
While the idea of seeing a wild crocodile is exciting, they're still extraordinarily rare. There are an estimated 1.5 million alligators in Florida, and no more than 2000 crocodiles estimated to live in the state. So if you see a wild crocodilian, especially in our area, there is still a 99.99% chance that it is an alligator. But live for that 0.01% chance everyone!