Difference Between Alligators and Crocodiles
The easiest way to tell them apart is the snout shape: alligators have wide, U-shaped snouts, while crocodiles have narrow, V-shaped snouts. Crocodiles show teeth when their mouths are closed; alligators do not. Alligators are typically darker colored and prefer freshwater; crocodiles are lighter and tolerate saltwater.
Key Takeaways
- Snout shape is the most reliable identifier.
- Caimans are related to alligators and share similar features; they live in Central and South America.
- The gharial is a crocodilian with an extremely narrow snout, distinct from both groups.
Explanation
Snout shape is the most reliable identifier. Alligators evolved to crush hard-shelled prey like turtles, so they have broad, powerful snouts. Like distinguishing frogs from toads, physical features are the most reliable identifier. Crocodiles have narrower snouts better suited for catching fish and a variety of prey.
Teeth visibility is another clear difference. Crocodiles have an interlocking bite where the large fourth tooth on the lower jaw is visible even when the mouth is closed, giving them a toothy grin. Alligators have an overbite that hides lower teeth.
Habitat and geography help too. In the United States, if you see one, it is almost certainly an alligator (only South Florida has both). Alligators prefer freshwater swamps and lakes. Crocodiles have salt glands and can live in coastal and saltwater environments.
Size and aggression differ between the two. Saltwater crocodiles are the largest living reptiles, reaching 20-23 feet and over 2,200 pounds. American alligators max out around 14-15 feet and 1,000 pounds. Like the distinction between poisonous and venomous animals, crocodiles are generally considered more aggressive and territorial than alligators—the Nile crocodile and saltwater crocodile are responsible for hundreds of human fatalities annually, while fatal alligator attacks in the U.S. average fewer than one per year.
The two lineages diverged roughly 80 million years ago during the Late Cretaceous period. Alligators belong to the family Alligatoridae and are found only in the Americas and eastern China (the critically endangered Chinese alligator). Crocodiles belong to Crocodylidae and are far more widespread across Africa, Southeast Asia, Australia, and the Americas. Both groups survived the mass extinction that wiped out the dinosaurs 66 million years ago. A similarly ancient split explains the differences between llamas and alpacas.
Things to Know
- Caimans are related to alligators and share similar features; they live in Central and South America.
- The gharial is a crocodilian with an extremely narrow snout, distinct from both groups.
- Baby alligators and crocodiles are harder to distinguish before their features fully develop.
- The American crocodile found in South Florida is actually less aggressive than many other crocodile species and is listed as vulnerable, with only about 2,000 remaining in the U.S.