The words 'crocodile' and 'alligator' are often used interchangeably to describe any large reptile with a toothy smile that is probably best not to go swimming with. But gators are not crocs and crocs are not gators.
Here we take a look at the difference between a crocodile and an alligator
What's the difference between a crocodile and an alligator?
True, they are both members of a single order of reptiles called the Crocodilia, but within that group, they belong to distinct families that went their separate ways about 90 million years ago - long before that asteroid killed off the dinosaurs.
The 18 species of crocodile are distributed throughout the world’s tropics. They include the largest of all living reptiles, the saltwater crocodile, which can exceed 6m long and well over a tonne in weight and inflicts the highest recorded bite force of any animal (1.7 tonnes). We named the saltwater crocodile one of the deadliest sea creatures in the world
Only two species go by the name of alligator – the American and the Chinese. However, the alligator family also includes the closely-related caimans, all six of which occur in Central and South America. The only place where crocodiles and alligators occur together is southern Florida.
How to tell the difference between a crocodile and an alligator
So how do we distinguish these two groups of amphibious predatory reptiles? One consistent difference lies in that infamous smile, which is straighter in alligators and wavier in crocodiles. Alligators have a slight overbite, so when their mouths are closed, the upper teeth obscure the lower ones. A crocodile’s upper and lower teeth are more aligned and slot in between each other, so both sets are visible. Its fourth lower tooth, which projects up against the outside of the upper jaw, is particularly obvious.
In general, crocodiles have narrower, pointier, v-shaped snouts compared toalligators. A notable exception is the mugger crocodile of south Asia, which has a broad, rounded alligator-like snout. And not all narrow-snouted crocodilians are crocodiles. The narrowest snouts of all belong to the two species of fish-eating, gharials. These are more closely related to crocodiles than alligators, but have been assigned to their own separate family.
There are also differences in overall colour. Crocodiles tend to come in lighter greenish browns, while alligators lean towards darker greys. And shape-wise, crocodiles are slightly longer limbed than alligators.
A close look at the skin reveals further differences. The scales of both groups are speckled with countless dark pores known as integumentary sense organs. These are distributed all over a crocodile’s body, but are restricted to the area around the mouth in alligators. Experiments have shown that these are more sensitive to touch than are primates’ fingertips. They are thought to sense the movements of water and prey animals.
While alligators are restricted to freshwater habitats, crocodiles prefer brackish environments, and some are saltwater specialists. Crocodiles – but not alligators - are able to secrete excess salt from their body by means of glands on their tongue. This might help explain why crocodiles have been able to circumnavigate the globe, while alligators are largely restricted to the Americas.