Hey! Watch out for that alligator! Or is it a crocodile? How are we supposed to tell them apart?
These scaly reptiles have been confusing and confounding humans for, well, pretty much forever. Alligators and crocodiles share plenty of similarities, but there are actually key differences between them.
In this article, we’ll explain the main difference between alligator and crocodile species, as well as where you can find them, what they eat, and their relationship with humans. Keep reading to become an expert on alligator vs crocodile similarities and differences!
Alligator vs Crocodile: A Brief Overview
Alligators and crocodiles are reptiles from the same order, Crocodilia. They’ve been around for about 200 million years—even outliving the dinosaurs! These animals are semiaquatic (able to live on both land and water) and are known to be excellent stealth hunters with keen vision and powerful jaws.
The word "alligator" originates from the Spanish word el lagarto, which means "the lizard." It is loosely defined as "any broad-snouted crocodilian." Within the Crocodilian order, their family is known as Alligatoridae.
An American alligator
The word "crocodile" comes from the Ancient Greek word krokódeilos, which also means "lizard." Within the Crocodilian order, their family is known as Crocodylidae.
An American crocodile
While there are only two living species of alligators, there are over a dozen species of crocodiles found around the world. Here's the full list of alligator vs crocodile species:
- American (Alligator mississippiensis)
- Chinese (Alligator sinensis)
- American (Crocodylus acutus)
- Cuban (Crocodylus rhombifer)
- Dwarf (Osteolaemus tetraspis)
- Freshwater (Crocodylus johnsoni)
- Gharial (Gavialis gangeticus)
- Morelet’s (Crocodylus moreletii)
- Mugger (Crocodylus palustris)
- New Guinea (Crocodylus novaeguineae)
- Nile (Crocodylus niloticus)
- Orinoco (Crocodylus intermedius)
- Philippine (Crocodylus mindorensis)
- Saltwater (Crocodylus porosus)
- Siamese (Crocodylus siamensis)
- Slender-Snouted (Crocodylus cataphractus)
Alligator vs Crocodile: Appearance
All crocodilians have roughly the same physiology: a lizard-like body and a tough, scaly skin, with an elongated snout and tails (flattened sideways). They have four limbs (legs) that are small in comparison to their overall bodies; webbed toes; and ears, nostrils, and eyes that sit on top of their heads.
Like all reptiles, crocodilians are cold-blooded and use their environment to help regulate their body temperature (e.g,. by hanging out in the sun to get warm, slipping into the shade or water to cool down etc.).
They're also defined by their jaws, which have incredibly powerful muscles for closing and weak muscles for opening. (This is why it’s so easy for humans to hold their jaws shut!)
A Chinese alligator (Daiju Azuma/Wikimedia Commons)
How to Identify an Alligator
Alligators are known to have darker hides than crocodiles, often appearing black or dark gray in color. One major difference between alligator and crocodile species is their snouts.
Alligators' main distinguishing feature is their wide, U-shaped snouts, which help them crack through tough shells of prey. When alligators close their mouths, usually only teeth from the top part of their mouths are visible.
Alligators can live anywhere from 30 to 50 years in the wild, although some in captivity have been estimated to live upwards of 70 years.
On average, alligators tend to be smaller than crocodiles, weighing anywhere from 70 to 1,000 pounds. Chinese alligators are also usually shorter than their American counterparts; they’ve been measured at 4.5 to 5 feet, whereas American alligators can range from 10 to 15 feet in length.
How to Identify a Crocodile
One of the main differences between alligators and crocodiles is their color. While alligators appear dark in complexion, crocodiles are usually a lighter brown, green, or gray.
Unlike alligators, crocodile snouts are long, narrow, and pointed (or "V-shaped"). These snouts are great for cracking through the variety of prey that crocodiles around the world eat.
Crocodiles also have toothy smiles when they close their mouths: teeth from both the top and bottom parts of their mouths can be seen.
A Nile crocodile (Leigh Bedford/Wikimedia Commons)
Crocodiles have a lifespan ranging from 70 to 100 years; however, their size can vary due to the number of species there are. The smallest species (dwarf crocodile) can measure about 6 feet in length and weigh around 13 to 15 pounds, whereas the largest species (saltwater crocodile) can measure more than 20 feet in length and weigh close to 2,000 pounds!
Where Do Alligators and Crocodiles Live?
Alligators are native only to China (Eastern; mostly in the Yangtze River) and the United States (Southern; particularly Florida and Louisiana). Because alligators can't process salt the way crocodiles can, they prefer warmer climates and freshwater environments, such as swamps, lakes, and rivers.
Unlike their alligator cousins, crocodiles can live in both freshwater and saltwater habitats. Their adaptability makes them more likely to be found throughout the world. In fact, the only continents that don't have crocodiles are Antarctica and Europe. The largest populations of crocodiles can be found in Central Africa (Nile crocodile) and Asia (Borneo; saltwater crocodile).
Global map showing where crocodilians can be found (Gretarsson/Wikimedia Commons)
Alligator vs Crocodile: Diet
Both crocodiles and alligators are carnivores with slow metabolisms. Because they cannot chew their food, they are known to swallow prey whole. Alligators eat everything from birds and fish to other reptiles, small mammals, and even fruit.
Meanwhile, because of their saltwater environment, crocodiles tend to eat frogs, birds, fish, crustaceans (crab), and large mammals (wildebeest and zebras).
Bats who dip their bellies in rivers to collect water make excellent prey for hungry crocodiles!
Alligators and crocodiles are known as "apex predators." This means they are at the top of their food chains and are vital to maintaining a habitat’s biodiversity. As is typical of apex predators (such as big cats, killer whales, and humans), these reptiles have no natural predators.
Nevertheless, crocodiles and alligators aren’t immune to being hunted. Case in point: big cats such as tigers, lions, and jaguars have been known to hunt and eat crocodiles when the mood (and hunger) strikes.
Habits and Behaviors of Alligators and Crocodiles
Lest you think all crocodilians do is slink through the water looking for prey, think again. Alligators and crocodiles have some interesting habits and social behaviors peculiar to their species.
Socialization and Play
Crocodiles are considered the most social species of reptiles. While perceived as quite solitary creatures, crocodiles will join forces for hunting and raising their babies; they are even known to form long-term relationships with one another!
Interestingly, crocodiles have their own social hierarchy based on size and height (the largest one wins!), which determines who gets the best spot for soaking up the sun (i.e., a "basking site") to help regulate their body temperature and who gets priority eating in large group feedings.
They're also known to play with each other, as well as with other animals and humans (in captivity). Despite this proclivity for fun, crocodiles are still aggressive animals (particularly when it comes to their territory or children) and will attack and kill humans if provoked or threatened.
Alligators are considered less social than their reptilian cousins, though they are known to spend time together while basking or swimming. A group of alligators is called a congregation, which tends to be made up of smaller alligators rather than larger ones who are more territorial and solitary.
Alligators are also known to dig "gator holes" in the dirt or mud when the weather gets to be too much. These tunnels help protect them from extreme temperatures (hot and cold).
In terms of movement, alligators and crocodiles are similarly athletic: both animals can run on land reaching speeds of about 11 miles per hour; however, their strength is swimming. Alligators and crocodiles can reach speeds upwards of 20 miles per hour in the water and can stay submerged for an hour at a time.
When they aren’t racing for food, alligators start mating in the late spring and continue into the summer (April-June). Crocodiles don’t begin mating until the summer months (July-August). Both alligators and crocodiles can lay dozens of eggs at a time, with the former averaging 20-50 eggs per batch and the latter averaging 10-60 eggs per batch.
What Is the Relationship Between Alligators, Crocodiles, and Humans?
As the human population continues to spread out, alligators and crocodiles increasingly appear in human environments. Climate change threatens the freshwater habitats of alligators, as the rise in sea levels could inundate freshwater sources with saltwater.
In addition, certain species are facing extinction due to being hunted by humans for their skin, the loss of their habitats, and contamination of their food from pesticides.
Among the crocodiles considered critically endangered are the Cuban, Orinoco, and Philippine. Meanwhile, several other crocodile species are considered vulnerable.
As for alligators, Chinese alligators are critically endangered; you’re more likely to see one in the zoo than in the wild, where reportedly fewer than 130 of them are left.
Summary: Alligator–Crocodile Differences
Alligators and crocodiles are two reptiles from the Crocodilia order. These semiaquatic animals are versatile eaters, fast swimmers, and socially complex. While they’ve been around for millions of years, human encroachment and hunting have left many types of crocodiles and alligators endangered.
So how can you tell the difference between alligator and crocodile species? Check out our chart below for a quick recap on alligator–crocodile differences and similarities.
Now that you're an expert on alligator–crocodile differences, it's time to learn even more about the animal kingdom. Check out our article on camel spider myths and the truth behind them.
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Brittany Logan graduated from Columbia University Graduate School of Journalism with a Master of Science with Honors. She has a dual-degree Master's from Sciences Po School of Journalism in Paris, and earned her Bachelor’s in Global Studies from the University of California, Santa Barbara. She has spent several years working in higher education- including as an English teacher abroad and as a teaching assistant in science writing at Columbia University’s Earth Institute.