Both alligators and crocodiles are members of the reptilian order Crocodylia, so are close relatives with many physical and behavioural similarities. However there are also many differences between these two large reptilian apex predators, and in this article we’ll look both the difference and similarities for alligators vs crocodiles.
Taxonomy-wise alligators and crocodiles belong to the Alligatoridae and Crocodylidae families respectively. Along with the Gavialidae family that contains the lone gavial (or gharial) these three families make up the order Crocodylia. The Crocodylidae family includes 15 species of “true” crocodiles, and the Alligatoridae family contains eight species of alligators and caimans.
Similarities between crocodiles and alligators
The Crocodylia lineage goes back 240 million years, meaning they’ve outlived the dinosaurs by a good 65 million years. Both crocodiles and alligators have a number of physical and behavioural similarities. These are:
- They’re reptiles that can live on land or in water, though are most at home in the water, and able to hold their breath for up to an hour.
- Their eyes are situated on the top of their heads which enable them to keep a lookout for prey whilst hiding underwater, and they have specialized vertical pupils that open extra wide to let in additional light, giving them powerful night vision. Though you can’t see their ears, the small slits they have are very sensitive to sound. Their sense of smell is highly developed due to special organs in their snouts.
- They all have powerful tails to swiftly propel them through the water.
- Both crocodiles and alligators are expert hunters and will eat pretty much anything they’re able to catch, from fish and turtles in the water to monkeys and buffalo on land.
- Their teeth are specialized specifically for spearing, so neither crocodiles nor alligators chew their food, rather swallowing their prey whole, or tearing it into large chunks to swallow.
- They both enjoy a limitless supply of teeth, having the ability to grow a new one any time one falls out.
These are the key alligator vs crocodile similarities. But how about if you wanted to know the difference between the two species, to know which one you’re looking at?
Differences between crocodiles and alligators
There are actually quite a number of big differences between crocodiles and alligators, making them quite easy to tell apart. From a distance, it’s not too difficult to tell the difference between alligator and crocodile simply by looking at the shape of the snout and the visibility of the teeth. Here’s our take on it:
1. Shape of snout
One of the most obvious differences between alligators and crocodiles is the shape of the snout. An alligator’s snout is broader, more rounded, and U shaped, whilst the crocodile’s snout is longer, narrower, more pointed and V shaped.
It’s speculated that the difference in snout shape is due to the difference in diet. The alligator’s broader jaw is stronger, and likely evolved to be able to break open hard-shelled prey like turtles that are abundant in their habitat. The narrower crocodile snout is more suited to hunting a variety of prey, including fish, reptiles, and mammals.
2. Bottom teeth
Alligator’s lower jaws are slightly smaller than their upper jaws, meaning that all of its lower teeth are hidden when its mouth is closed. You can only see the downward-pointing teeth in an alligator’s upper jaw when its mouth is closed.
Crocodiles look much toothier when their mouths are closed. Since their upper and lower jaws are roughly the same sizes, their upper and lower teeth interlock when they shut their mouths, giving the appearance of a ragged smile. In particular, the fourth tooth on each side of a crocodile’s lower jaw sticks up over the upper lip.
3. Size and weight
Both alligators and crocodiles are massive reptiles, though crocodiles are the larger of the two species on average.
Alligators can grow to be anywhere from 3 to 4.5 meters, weighing in at an average of 230 kg. Crocodiles can grow up to 5.5 meters in length, reaching almost 1 ton!
Crocodiles are generally lighter colours than alligators. Crocodiles tend to be a light tan or olive colour, whereas alligators are usually a dark blackish-grey. An interesting fact on this point is that the shade of an alligator’s skin depends upon the type of the water it swims in – tannic acid from overhanging trees makes them darker whilst algae makes them greener.
5. Skin texture
Both crocodiles and alligators have sense organs on their skin in the form of small pits called integumentary sensor organs (ISOs). These help them to locate prey by sensing small pressure changes in water made by other animals. The ISOs look like small dots, and cover almost the whole of a crocodile’s body, but only around the mouth of an alligator.
6. Geographic range
Crocodiles can be found across the world in Africa, Australia, Southeast Asia, North America, South America, and Central America – wherever slow-flowing rivers and grasslands dominate.
Alligators thrive in China and the Southeastern portion of the United States, particularly Florida and the Gulf Coast states.
In the US alligators vastly outnumber crocodiles, with around 3 million alligators to an estimated 2,000 crocodiles. The Florida Everglades is the only area in the world where both alligators and crocodiles are found living together.
7. Preferred habitat
One of the key alligator and crocodile differences is in their preferred habitat.
Crocodiles tend to prefer swamps and slow-moving rivers, and are able to tolerate saltier waters like mangroves and estuaries in Africa, North America, South America, and Asia. Crocodiles have well-developed lingual salt glands in their tounges that expel excess salt from their bodies and allows them to live for weeks at a time in saline waters.
Alligators don’t have such efficient salt glands, which leads to them sticking to freshwater habitats, such as freshwater marshes, lakes, and slow-moving streams. This said alligators can sometimes be found in brackish water (a mixture of salt and freshwater).
This physical difference between crocodile and alligator helps explains why crocodiles have managed to colonize the islands of the Caribbean, and alligators haven’t.
8. Danger to humans
Whilst alligators are most definitely dangerous animals, they are relatively timid when compared to crocodiles.
If approached by a human, an alligator will usually try to escape by heading for the nearest water, unless they’re surprised, provoked, or defending their young.
Crocodiles are typically more aggressive than alligators, making them the more dangerous animal, particularly in Africa where attacks fatal on humans are fairly common. They’re generally bad-tempered and far more likely to attack humans, even unprovoked.
Australian saltwater crocodiles are recognised as the most dangerous in the world, followed by the Nile crocodiles found in much of Africa. American crocodiles a more timid breed of crocodile and rarely attack humans. In fact, in the US, you are far more likely to be attacked by an American alligator than an American crocodile, though attacks by either are rare.
Common alligator v crocodile questions:
Are alligators and crocodiles the same species?
Both alligators and crocodiles are members of the reptilian order Crocodylia, but belong to different families. Alligators belong to the Alligatoridae family which contains 8 species, and crocodiles belong to the Crocodylidae family which has 15 species.
Who would win in a fight between an alligator and a crocodile?
This depends on the species and age, but the biggest crocodile is far bigger than the biggest alligator, so the crocodile would be victorious in a fight.
Which is bigger alligators or crocodiles?
Both alligators and crocodiles are massive reptiles, though crocodiles are the larger of the two species on average. Alligators can grow to be anywhere from 3 to 4.5 meters, weighing in at an average of 230 kg. Crocodiles can grow up to 5.5 meters in length, reaching almost 1 ton!
Do crocodiles eat alligators?
Adult crocodiles are known to eat young crocodiles and young alligators. It’s unlikely that an adult crocodile would hunt an adult alligator.
And that’s the lots for this round-up of crocodile vs alligator. What do you think – any difference between alligators and crocodiles that surprise you? Or any differences you think we should add to this post? Let us know in the comments section below!