What’s the difference between alligator and crocodile? How can you tell?
These are the two most common questions people ask about crocodilians. There really is no one, simple answer!
Alligators and crocodiles are roughly twice as evolutionarily distant as cats and dogs.
Our furry friends last shared a common ancestor around 42 million years ago. Genetic and fossil evidence suggests that crocodiles and alligators separated around 90 million years ago.
Over the years since they split, crocodiles and alligators have both occupied similar ecological roles.
Both groups are specially adapted to lurk in shallow water. They ambush prey such as fish, birds, and mammals.
Their overall body shape – or “morphology” – is well suited for this role. For the most part, it has remained relatively similar as a result. If it’s not broken, why fix it?
Still, like cats and dogs, crocodiles and alligators have many distinct morphological differences.
Unfortunately, there are no hard-and-fast rules, and each has one or more exceptions.
Once you know what to look for, it’s still reasonably easy to tell the difference between crocs and gators.
We’ll explain all of the significant differences in this guide, including the differences in size, snout characteristics, and teeth.
We’ll also discuss some of the more unusual – and lesser-known – crocs, such as gharials, false gharials, dwarf crocodiles, and caimans.
To briefly summarize, here’s a helpful diagram regarding one of the most distinctive visual differences:
In This Article
Background: The Crocodilian Family Tree
Crocodilians (crocs, alligators, gharials, and caimans) are only distantly related to other reptiles.
In fact, they are far more closely related to birds!
Birds, dinosaurs, and crocodilians belong to a group called the “Archosaurs” or “ruling reptiles.”
The archosaurs split from other reptiles – such as snakes and lizards – in the late Devonian period over 250 million years ago.
Fun Fact: Their complex physiology suggests that early crocodilians may have been warm-blooded, indicating that cold-bloodedness “re-evolved” in the ancestors of modern crocs!
The ancestors of modern crocs comprised a diverse group of animals.
During the Triassic, Jurassic, and Cretaceous periods, there were many crocodile-like animals – of all different shapes and sizes.
Among them were giant filter-feeders, armored herbivores, and even slender, dog-like creatures!
Some prehistoric croc ancestors even roamed the open seas. They had elongated bodies and fin-like tail projections.
Today, only around 25 species remain. They’re known as the crocodilians.
Several new crocodilian species have been recently described. More are likely to follow in the next few years.
All of the surviving crocodilian species belong to one of three families:
- Gavialidae – Gharials and false gharials; the last surviving remnants of an ancient group of slender-snouted crocodilians
- Alligatoridae – Alligators and caimans
- Crocodilidae – Crocodiles, slender-snouted crocodiles, and dwarf crocodiles
There are a few critical morphological differences between crocodiles and alligators.
For instance, alligators have integumentary sensory organs (ISOs, which appear as tiny black dots on the skin) only on their jaws.
Crocs have ISOs scattered around their entire body.
All members of the croc family also possess lingual salt glands. Alligators lack these altogether.
Unfortunately, these aren’t excellent characteristics for identifying crocs or alligators. Both would require you to get up-close and personal!
In the next section, we’ll discuss the best ways to distinguish crocs from gators – but remember that there are no perfect methods.
Alligators Have A “U-Shaped”, Crocodiles Have A “V-Shaped” Snout
Snout shape is one of the key differences that allow us to distinguish most crocodiles from alligators.
Most crocodiles have a “V-shaped” snout. It’s broader towards the back of the head and narrower towards the tip. Their teeth also interlock when the mouth is closed.
Alligators have more “U-shaped” snouts. These are broader and more curved, as opposed to pointed.
The mugger crocodile is a notable exception to this rule. It possesses a broad, “U-shaped” snout compared to other crocodiles.
The mugger croc only lives in Southeast Asia, Pakistan, and the Indian subcontinent – areas uninhabited by alligators.
Extremely large, adult saltwater and Nile crocodiles can also have less angular snouts than other crocs. They belong to the largest crocodiles ever recorded. But again, their ranges don’t overlap with gators.
Alligators Have Overbite While Crocodiles Have Interlocking Teeth
Teeth are also a helpful characteristic for distinguishing crocs from gators.
Alligators (usually) have an “overbite.” Their upper jaw overhangs slightly above the lower jaw.
When the mouth is closed, this often means that only the teeth on the upper jaw are visible.
Some alligators can break this rule with large, protruding lower teeth. This is relatively uncommon. Caiman, on the other hand, often have teeth similar to those of a crocodile.
Crocodiles possess interlocking teeth. The teeth of both the upper and lower jaws remain visible when the mouth is closed.
Crocs also have a noticeably enlarged fourth tooth on either side of the lower jaw. This tooth fits into a unique groove on the upper jaw when the mouth is closed and remains visible.
Alligators also possess an enlarged fourth tooth, but it fits into a groove inside of the upper jaw, meaning that it is NOT visible when the animal’s mouth is closed. Read our article on alligator teeth to get every detail and even if you can (or should) purchase them.
Crocodiles Are Larger Than Alligators
As a general rule, crocodiles are larger than alligators. There’s a considerable amount of size overlap between the two families.
The Australian saltwater crocodile (Crocodylus porosus) is the biggest of all crocodilians alive today.
The largest crocodile ever recorded was Lolong, who measured a whopping 20 ft (6 m) in length and weighed over 2,000 lbs!
Nile crocodiles (Crocodylus niloticus) and American crocodiles (Crocodylus acutus) are other close contenders, regularly exceeding 16 ft (around 5 m) in length.
The dwarf caiman (a member of the alligator family) is the smallest crocodilian species, topping out at just over five feet (1.5 m) in length.
Dwarf crocodiles are only slightly larger – measuring up to around six feet.
The black caiman (Melanosuchus niger) is the largest member of the alligator family. It can reach proportions close to those of the largest crocodiles, also exceeding 16 ft in length.
Are Crocodiles and Alligators Related?
Crocodiles and alligators are closely related. They’re both members of the order Crocodylia. In fact, all crocodilians, including gharials and caimans, belong to this order.
Originally, crocodiles and alligators were grouped into the same family as well. However, scientists have since split them into two separate families.
Alligators and Caimans belong to the family Alligatoridae, and crocodiles belong to the family Crocodylidae.
Gavials and Gharials are also close relatives of the crocodile, and they belong to the family Gavialidae in the same order.
Minor differences in the anatomy and habits of each of these families sets them apart from their relatives.
Alligator vs. Crocodile vs. Caiman vs. Gharial
The distinction between alligator vs. crocodile vs. caiman is an evolutionary one.
Alligators are members of a different family to crocodiles, but the alligator family (Alligatoridae) includes both alligators and caimans.
The “true” alligators (genus: Alligator) are native to North America and a small part of China. There are only two species: the American and Chinese alligators.
Caimans are native to Central and South America. There are six caiman species.
All members of the alligator family lack salt glands and are unable to survive in saltwater for extended periods.
Alligators (Genus: Alligator)
Alligators are dark, broad-snouted crocodilians native to North America and a small region of China. The genus Alligator includes only two extant (living) species:
- The Chinese Alligator (sinensis) – A relatively small species, now critically endangered in the wild. They possess dark greyish skin and a short, shovel-like snout.
- The American Alligator (mississippiensis) – A large, robust species that can grow to 15 ft and weigh over 1,000 lbs. They’re also dark greyish, but with a slightly longer snout than the Chinese alligator. They were formerly endangered in the US, but are now thriving as a result of sustainable management.
Caimans (Genera: Caiman, Paleosuchus, and Melanosuchus)
Caimans are members of the alligator family endemic to Central and South America. This group includes a few different genera:
- The Black Caiman (Melanosuchus niger) – Enormous, black, and alligator-like animals with distinctive spots on their lower jaw.
- The Dwarf Caimans (Genus: Paleosuchus) –The smallest of all crocodilians. Both species are dark brown with a covering of sharp spines.
- The Spectacled, Yacaré, and Broad-Snouted Caimans (Genus: Caiman) – Medium-sized animals that live throughout Central and South America. They all possess a distinctive pointed projection above each eye.
Crocodiles are members of “Crocodilidae” – a family separate from the alligators.
Crocs inhabit tropical habitats around the globe. Some only inhabit freshwater wetlands, while others (like the Australian saltwater croc) can venture into saltwater for long periods.
The crocodile family includes three different genera:
- The Crocodiles (Genus: Crocodylus) – This group contains the largest of all crocodilian species. Most are olive-brown or greyish with a triangular head and interlocking teeth. Some inhabit freshwater environments only, while others can spend extended periods at sea.
- The Dwarf Crocodiles (Genus: Osteolaemus) – Small, broad-snouted crocodiles native to Sub-Saharan Africa.
- The Slender-Snouted Crocodiles (Genus: Mecistops) – Elusive, medium-sized crocodiles native to West Africa. They possess a slender, highly-tapered snout (hence their name), making them appear similar to gharials and false gharials.
Crocodile species range in length from 6 ft (approx. 2 m) to over 20 ft (6 m).
Gharials and False Gharials
Gharials (Gavialis gangeticus) are probably the most unusual of all crocodilians.
Native to India and Nepal, these gigantic fish-eaters possess a highly elongated, slender snout filled with sharp, needle-like teeth.
Mature male gharials also boast an unusual projection at the very tip of their snout.
This strange lump – known as the “Ghara” – helps them produce distinctive noises during the breeding season. People usually describe this as a sort of loud “pong.”
Gharials are highly distinctive and cannot be mistaken for any other crocodilian within their range.
They do look similar to the Southeast Asian “false” gharial – or Tomistoma. Despite being “gharial-like” in appearance, the Tomistoma was only recently added to the gharial family.
The exact classification of the Tomistoma has been hotly debated over the past few decades.
American Crocodile vs. American Alligator
Two crocodilians are native to Florida: the American crocodile (Crocodylus acutus) and the American alligator (Alligator mississippiensis).
In this section, we’ll compare and contrast these two different species and explain a few easy ways to identify crocodilians in Florida.
The American Crocodile (Crocodylus acutus)
Range and Habitat:
American crocs mostly live throughout South and Central America. There is also a crocodile population of around 2000 individuals in South Florida.
Like all crocodiles, American crocs are a tropical species. They require warm temperatures year-round to survive.
This requirement limits their range to only the warmest parts of Florida. Though gators live throughout the state, crocs only venture as far north as the Tampa Bay area.
Unlike alligators, American crocs can tolerate long periods in saltwater. You’ll usually find them in mangrove swamps along the coast.
American crocs are among the largest of all crocodilians.
Adult males can reach lengths of up to 20 ft (6 m).
These days, crocs rarely – if ever – achieve such a size. Nowadays, the largest individuals seen in the wild are around 16 ft (5 m).
An American crocodile’s skin is usually light olive or grey.
Like most “true” crocs, they possess a long, triangular head.
Their snouts are slender, with large, interlocking teeth visible when the mouth is open or closed.
While young crocodiles often appear more slender than alligators, adults do become broader with age. Large males can also develop wider, more robust-looking jaws.
American crocodiles usually possess a slight hump between the eyes and the nostrils, making them appear slightly different from Nile or saltwater crocodiles.
Relationship with Humans:
Due to their large size, American crocodiles can hunt larger prey than most alligators, making them more of a threat to humans and livestock.
This species is responsible for the majority of fatal crocodile attacks in Central and South America.
Even still, they’re considerably more docile than their Australian and African counterparts.
The American Alligator (Alligator mississippiensis)
Range and Habitat:
Gators inhabit coastal wetlands throughout Florida and the rest of the Southeastern United States.
These habitats include freshwater marshes, lakes, swamps, and slow-flowing rivers.
The largest alligator ever recorded measured 15 ft and 9 inches and weighed over 1,000 lbs.
Though the largest alligators can top 15 ft in length, they rarely do. Even gators above nine or ten feet are a moderately rare sight.
Alligators’ skin is dark black or greyish brown. Their underside is a much lighter cream or yellowish color.
They possess a large, “U-shaped” head, usually with a slight overbite. The teeth of their lower jaw are typically out of sight when their mouths are closed.
Relationship with Humans:
In Florida, alligators are so widely distributed that it’s safe to assume that any body of water in the Sunshine State could contain one or more alligators.
Still, for the most part, alligators are either too small or too skittish to pose a threat to humans.
Large alligators do occasionally launch unprovoked attacks on humans. Fatal attacks are sporadic, with only around 25 having been reported since the 1920s!
Aggressive behavior is most common in areas where humans feed alligators. Feeding alligators causes them to learn to associate us with food rather than to be afraid.
Croc, Caiman, or Gator? Easily Identifying Crocodilians in Florida
South Florida is the only place in the world where crocodiles (C. acutus) and alligators (A. mississippiensis) naturally coexist.
More recently, the state has also become home to a population of non-native spectacled caiman (Caiman crocodylus).
For now, Caimans have only been found in Miami-Dade and Broward Counties.
All three are pretty elusive animals, making them difficult to spot in the wild.
If you do spot a croc, caiman, or gator, you’ll often only be able to glimpse its eyes and snout before it sinks beneath the surface of the water.
In these instances, a pointed “brow” above each eye is characteristic of the non-native spectacled caiman. Native crocs and gators’ eyes are more rounded in appearance.
If you’re lucky enough to catch a glimpse of the animal’s body, remember that gators are much darker in color than American crocodiles or spectacled caiman.
If its skin appears near-black in color, it’s likely to be an alligator .
The croc and caiman have similar greyish brown coloration and can be hard to distinguish. To tell the difference, note the animal’s size and head shape.
Spectacled caiman have not been known to exceed 9 ft in length, even in their native range. Crocodiles can reach lengths of up to 20 ft.
Caimans also possess a broader, more rounded snout. Though not as broad as an alligator’s, the caiman’s snout is far more “U-shaped” than the American crocodile’s.
Lastly, most adult American crocs possess a large, smooth bump between their nostrils and eyes. This bump is lacking from both caimans and alligators.
Alligator vs. Crocodile Fight
Crocs and gators coexist in (relative) peace and harmony in South Florida. They’re sometimes housed together in captivity.
Both are generalist predators. They will happily prey on any animal small enough to be overpowered and eaten (including other crocodilians).
Depredation of juvenile crocs or gators by adults is a fairly common occurrence.
These animals are highly territorial, and adults will fight to solve disputes and even maintain social hierarchies.
Their fights can – and do – inevitably occur as species compete for food or territory.
In Florida, where American alligators live alongside American crocodiles, no inter-species depredations have yet been reported.
American crocodile vs. American alligator conflicts have been observed in captive enclosures.
There are also reports of critically endangered Orinoco crocodiles preying on juvenile spectacled caiman in Columbia and Venezuela.
Fun Fact: Crocs and gators aren’t the only predators found in Florida’s waterways. There have been numerous reports of conflict between bull sharks and alligators in Florida.
Crocodile vs. Alligator – Who Would Win?
“Crocodile vs. Alligator – Who Would Win?” is a question that immediately springs to mind when many people hear of American crocs and gators living side by side in Florida (or caimans and Orinoco crocs battling things out in South America).
There’s no question that the winner of any crocodilian fight comes down to size.
The largest, most powerful crocodiles dwarf the largest alligators by as much as five feet.
As adult crocodiles grow, they also gain a lot of weight! A fully grown male saltwater crocodile can weigh over twice as much as even the largest alligators.
Strangely, however, some zookeepers report that large alligators tend to dominate similarly-sized American crocs in captivity!
Are Crocodiles or Alligators More Dangerous?
Crocodile attacks can be a severe problem for people who spend time in and around croc-inhabited waterways.
The most aggressive (and therefore dangerous) crocodilians – in terms of human depredation – are the Nile and Saltwater crocodiles.
Unfortunately, rural communities in developing countries are disproportionately affected by human-crocodile conflicts.
It’s also tricky for scientists to accurately estimate the number of incidents per year, as many attacks go unreported.
Nile crocodiles may be responsible for hundreds of human fatalities per year, though data on the subject are lacking.
In the United States, attacks by crocodilians do happen, but they’re a relatively rare occurrence.
More people are killed in Florida by lightning strikes (per year) than alligators.
Crocodilian-related incidents in the US usually involve alligators.
This statistic is NOT due to alligators being more aggressive than crocs, but due to them being more widespread.
Most attacks occur while people are wading, swimming, or fishing in shallow water.
The best ways to prevent alligator attacks are:
- NEVER feed or harass wild alligators
- Keep pets away from the water’s edge
- Swim only during daylight hours and with a friend
- Stay out of water bodies that aren’t designated for swimming, particularly murky water, lakes, or slow-flowing rivers
- If you MUST enter the water, use a sturdy walking stick or branch to prod before you step. This tool may help you to avoid stepping on an alligator
For more safety advice and information about crocodile and alligator attacks in Florida, check out this helpful guide produced by the CrocDocs team at the University of Florida.
Are Crocodiles More Aggressive Than Alligators?
Yes, crocodiles are more aggressive than alligators.
While both animals could give you a thrashing, alligators tend to be timider. They’d rather avoid you than eat you (in most cases).
Crocodiles are intentional predators with short tempers. They have a reputation for attacking people, other animals, and even boats that move near them.
While the crocodile isn’t always hungry, it spends its life in attack mode. Alligators are generally much calmer.
For general information about crocodilians and other reptiles, check out our top five books on herpetology.
What else would you like to know about crocodilians? Tell us in the comment section below.