Alligator vs crocodile: how to tell them apart (and which is more dangerous)

A dark shape lies still in a mangrove creek in southern Florida. Only its eyes and nostrils break the surface. Is it an alligator or a crocodile? This is one of the few places on Earth where it really could be either.

Here is the quick answer to alligator vs crocodile. An alligator has a broad, U-shaped snout, and with its mouth shut you mostly see upper teeth. A crocodile has a narrower, V-shaped snout, and the big fourth tooth of its lower jaw sticks up outside the upper lip when the mouth is closed. Alligators are usually darker. Below you will find a side-by-side chart, the hidden science that separates them, and honest answers on size, bite force and danger.

Alligator vs crocodile: the comparison chart

This table compares the American alligator with the “true” crocodiles, using the American crocodile (the one that shares Florida with alligators) and the saltwater crocodile (the biggest) as examples. Every row is drawn from the sources listed at the end.

Alligator vs crocodile at a glance

Feature	Alligator (American alligator)	Crocodile (American and saltwater crocodiles)
Family	Alligatoridae (alligators and caimans), 8 species	Crocodylidae (“true” crocodiles), 16 species
Snout from above	Broad and rounded, U-shaped	Narrower and tapered, V-shaped (but the saltwater crocodile’s snout is fairly broad)
Mouth closed	Lower fourth tooth hidden in a socket; mainly upper teeth show	Lower fourth tooth sits in a notch and shows clearly
Colour	Usually black or very dark; can look olive, brown or grey	American crocodile: greyish green; saltwater crocodile: golden tan to grey or black
Sensory pits (ISOs)	On the jaws and head only	On the jaws and on scales all over the body
Salt glands on tongue	Absent	Present
Usual water	Fresh water; sometimes brackish	American crocodile: brackish and salt water; saltwater crocodile: fresh water to open sea
Where	South-eastern USA (plus the Chinese alligator in the lower Yangtze)	Tropical Americas, Africa, Asia and Australia
Large adult males	About 4–4.5 m (13–15 ft)	American crocodile 4–4.5 m; saltwater crocodile 4.5–5.5 m, rarely over 6 m
Strongest bite measured	9,452 N (2,125 lbf)	16,414 N (3,690 lbf), saltwater crocodile
Young	Dark with yellow stripes	American crocodile: light with dark stripes
IUCN Red List	Least Concern	American crocodile Vulnerable; saltwater crocodile Least Concern

Sources: IUCN SSC Crocodile Specialist Group [19][20][22]; FWC [10][11]; NPS [8][9]; Leitch & Catania 2012 [2]; Taplin et al. 1982 [4]; Erickson et al. 2012 [1]; Australian Museum [17]. The species counts follow the Crocodile Specialist Group’s list of 26 recognised crocodilians [20].

How can you tell an alligator from a crocodile in 3 seconds?

Look at three things, in this order. First, the closed mouth: a crocodile’s enlarged fourth lower tooth shows on each side, while an alligator’s is hidden. Second, the snout shape from above: U for alligator, V for crocodile. Third, the colour: alligators are usually black, crocodiles greyish green or tan.

The teeth test works because of how the jaws fit together. In all crocodilians the fourth tooth back on the lower jaw is greatly enlarged. In alligators and caimans it slots into a socket in the broad upper jaw, so its tip disappears. In “true” crocodiles the upper jaw has a notch instead, and the tooth rests in it, in plain view. The Crocodile Specialist Group calls this “a major distinction” between the families [19]. The Smithsonian’s National Zoo uses the same test [15].

Snout shape is a good second clue, but not a perfect one. The Australian Museum describes the saltwater crocodile’s snout as broad [17]. And in Erickson’s measurements of all living crocodilians, the mugger crocodile of India had a snout almost as wide for its length (a ratio of 0.66) as the American alligator (0.69) [1]. So use the teeth to confirm.

Colour is the weakest clue. The National Park Service says adult alligators can be olive, brown, grey or nearly black. Algae-filled water makes their skin look greener, and tannins from overhanging trees make it darker [9].

Are alligators and crocodiles in the same family?

No. They are cousins in the same order, Crocodylia, but in different families. Alligators and caimans make up Alligatoridae, with 8 living species. “True” crocodiles make up Crocodylidae, with 16. The gharial and the tomistoma make up a third family, Gavialidae. Together they are the 26 crocodilians recognised today [19][20].

The two families split a very long time ago, roughly 80 to 100 million years ago in the Cretaceous [6][24]. That is about twice as long ago as cats and dogs parted ways. It is also why an alligator and a crocodile cannot interbreed [24]. Hybrids do happen inside the crocodile family: wild Cuban crocodiles readily hybridise with American crocodiles where the two meet [23].

Crocodilians are also more closely related to birds than to lizards or snakes. Florida’s wildlife agency explains that crocodilians and dinosaurs share a common ancestor, and birds are living dinosaurs [12]. Meet more reptiles and their relatives on our animals hub.

Where do caimans and gharials fit?

Caimans are alligatorids from Central and South America. The spectacled caiman rarely exceeds 1.5 m (5 ft), and an introduced population now lives in south-eastern Florida [25]. Gharials have extremely long, thin snouts. The gharial of South Asia remains almost entirely a fish-eater even at very large sizes [22], and it has the weakest bite for its size of any living crocodilian [1]. It is listed as Critically Endangered [21].

What hidden differences do scientists use?

Two invisible features separate the families: tiny touch sensors in the skin and salt glands in the tongue. Crocodiles carry the sensors on scales all over the body and have working salt glands. Alligators carry the sensors only on the head and have no salt glands, which helps explain why they rarely go to sea.

Integumentary sensory organs: skin that feels ripples

Look closely at a crocodilian’s jaws and you will see hundreds of small dark dots. These are integumentary sensory organs, or ISOs: tiny domes in the skin packed with nerve endings. In 2012, the biologists Leitch and Catania counted roughly 4,000 on an American alligator and 9,000 on a Nile crocodile [2].

All crocodilians have them densely on the jaws. Only crocodiles and gharials also have them on the scales of the body [2]. The organs respond to a touch of just 0.08 mN (millinewtons). The researchers found that, despite the armour, they give crocodilians a sense of touch more sensitive than primate fingertips [2]. Their results fit the idea that ISOs help detect the ripples made by prey on the water surface [2]. A later study found that the ISOs of Nile crocodiles and spectacled caimans also respond to temperature and acidity [26].

Salt glands: why crocodiles can go to sea

For years, scientists were puzzled that sea-going crocodiles seemed to have no salt glands. Then, in 1981, Taplin and Grigg found them in the tongue of the saltwater crocodile. The glands push out a concentrated salt solution [3]. Each saltwater crocodile has 28 to 40 of these glands, each with its own pore on the top of the tongue [5].

A year later, the same team reported lingual salt glands in the American crocodile and the Australian freshwater crocodile, and their absence in the American alligator and the spectacled caiman [4]. The National Park Service notes that alligators can cope with some salt for short periods but lack the salt-secreting glands of crocodiles [9].

A 2025 study of crocodilian family trees suggests salt tolerance was the ancestral condition, and that the alligator line lost it early in its history [6]. That one loss helps explain the whole map: crocodiles crossed oceans to reach every tropical continent, while alligators stayed in fresh water. Salt glands are a textbook physiological adaptation (see structural, behavioural and physiological adaptations).

Where do alligators and crocodiles live?

Alligators live in only two countries: the American alligator in the south-eastern United States and the Chinese alligator in the lower Yangtze region of eastern China. Crocodiles live across the tropics of the Americas, Africa, Asia and Australia. The only place where wild alligators and crocodiles share the same landscape is south Florida [7][8].

The American alligator ranges from North Carolina to Texas and south-east Oklahoma, mainly in fresh lakes, slow rivers and wetlands [12]. It occurs in all 67 Florida counties [13]. The Chinese alligator is now limited mainly to Anhui and Zhejiang provinces [16].

Why is south Florida the meeting point?

South Florida is where two ranges just touch. Everglades alligators live at the southern edge of their range; American crocodiles live at the northern edge of theirs, which runs south through the Caribbean to Peru and Venezuela [8][11]. The alligators keep mainly to fresh marshes. The crocodiles keep mainly to brackish ponds, coves and creeks in the mangroves, though canals sometimes carry them inland [10][11].

Note the word “alligators”. Caimans, which belong to the alligator family, share rivers with American crocodiles in Central America, for example on Costa Rica’s Caribbean coast [27].

Which is bigger, an alligator or a crocodile?

The biggest crocodiles are bigger than the biggest alligators. Large male saltwater crocodiles reach 4.5–5.5 m, and the largest reliably measured wild one was at least 6.15 m (20 ft 2 in). Large male American alligators reach about 4–4.5 m (13–15 ft). Many smaller crocodile species, though, are shorter than an alligator.

The detail matters. Smithsonian’s National Zoo gives average adult American alligators as 3.4 m (11.2 ft) for males and 2.6 m (8.2 ft) for females, with exceptional males nearing 454 kg (1,000 lb) [15]. Florida’s official records are a 4.36 m (14 ft 3.5 in) male for length and a 473 kg (1,043 lb) male for weight [12].

For saltwater crocodiles, the Australian Museum puts average adults at 3–5 m. The largest reliably measured wild animal was a headless carcass from the Mary River in Australia’s Northern Territory in 1974, estimated at no less than 6.15 m once its 66.6 cm skull was added [17]. The Guinness World Records holder is Lolong, a saltwater crocodile captured in the Philippines in 2011. He measured 6.17 m (20 ft 3 in) and weighed about 1,075 kg (2,370 lb) [18]. That record is for captivity, and Lolong died in 2013 [18].

Which has the stronger bite, an alligator or a crocodile?

The saltwater crocodile has the strongest bite ever measured in any animal: 16,414 newtons (3,690 pounds of force), recorded by Gregory Erickson’s team in 2012. The highest they measured in an American alligator was 9,452 N (2,125 lbf). Body size, not snout shape, explains almost all the difference [1].

Erickson and colleagues tested 83 adults from all 23 crocodilian species recognised at the time. They found that body mass accounted for nearly all the variation in bite force between species, and that “jaw shape demonstrates surprisingly little correlation to bite force” [1]. A big alligator and a crocodile of the same weight bite about equally hard. The saltwater crocodile wins only because it grows heavier. The team estimated that 6.7 m saltwater crocodiles were likely capable of 27,531–34,424 N (6,187–7,736 lbf) [1].

The “3,700 psi” mistake

Many websites say a saltwater crocodile bites at “3,700 psi” and an alligator at “2,125 psi”. Those numbers come from Erickson’s study, but the unit is wrong. They are pounds of force (lbf), not pounds per square inch (psi), which is a pressure [1]. The paper does report pressures too, at the tip of single teeth, and those are vastly higher: up to 1,388 megapascals, or about 201,000 psi, for the Orinoco crocodile [1]. For more record bites, see which animal has the strongest bite force. Crocodilians rely on that bite alone; for a reptile that may add venom, read whether Komodo dragons are venomous.

Which is more dangerous, an alligator or a crocodile?

Crocodiles, overall, but it depends on the species. Saltwater and Nile crocodiles cause hundreds of recorded deaths. The American alligator bites people far less often, and under 5% of its recorded attacks were fatal. The shy American crocodile rarely causes conflict in Florida [8][22].

The best global data come from CrocBITE, a database of crocodilian attacks. The IUCN Crocodile Specialist Group published CrocBITE totals for 2010–2020, with all the usual warnings: many attacks in remote areas go unreported, and fatal ones are more likely to be recorded [22]. From those totals we calculated the share of recorded attacks that were fatal.

Recorded crocodilian attacks on people, 2010–2020 (CrocBITE)

Species	Fatal	Non-fatal	Total	Share fatal (our calculation)
Saltwater crocodile	668	682	1,350	49%
Nile crocodile	696	309	1,005	69%
Mugger crocodile	171	252	429	40%
American crocodile	26	159	185	14%
American alligator	6	121	127	5%

Source: IUCN SSC Crocodile Specialist Group, summarising CrocBITE [22]. Percentages are fatal ÷ total, rounded.

Florida keeps its own long record. From 1948 to 2025 the Florida Fish and Wildlife Conservation Commission (FWC) logged 500 unprovoked alligator bites, 32 of them fatal [14]. Its fact sheet puts the chance of a Florida resident being seriously injured in an unprovoked alligator incident at roughly one in 3.1 million [13]. Most alligators are naturally afraid of people, but they lose that fear when people feed them, which is why feeding them is illegal [13].

Florida’s crocodiles are shy. A crocodile that crashes noisily into the water is frightened, not attacking, and one basking with its mouth open is cooling down [10]. The Park Service notes that conflict with American crocodiles “rarely occurs” [8].

How to stay safe around both

• Stay at least 5 m from the water’s edge where crocodilians live, and at least 10 m from any crocodilian you see [22].
• Never feed alligators or crocodiles. In Florida it is illegal as well as dangerous [13].
• Keep children and dogs away from the water; dogs resemble alligators’ natural prey [13].
• Never pick up even a small alligator. FWC warns that handling small alligators can cause injury, and keeping one is illegal [13].

Alligator vs crocodile: who would win a fight?

A large saltwater crocodile would almost certainly beat any alligator, because it is longer, heavier and bites harder. Between the two that actually meet, the American alligator and the American crocodile, it would come down to which animal is bigger. We found no scientific report of a fight between them.

The evidence is all indirect. Large males of both American species reach about 4–4.5 m [22], and Erickson’s work shows that bite force follows body weight, not family or snout shape [1]. So a 300 kg alligator should out-bite a 150 kg crocodile, and the reverse would also hold. The two also rarely share water: alligators stay mainly in fresh marshes and crocodiles in salty mangrove creeks [9][10].

Lions and tigers have the same problem: they never meet in the wild either. See tiger vs lion for how we weigh that kind of question.

What do alligators and crocodiles do for their ecosystems?

Both are top predators that also feed many other animals when young. The American alligator does more: the National Park Service calls it a keystone species of the Everglades, because the “alligator holes” it digs hold water through the dry season and shelter other wildlife [9].

Alligators. Young alligators eat insects, small fish and frogs; adults eat fish, turtles, small mammals, birds and other reptiles [9]. Raccoons are the main predators of their nests, and about a third of nests are destroyed by predators or floods. Young alligators are eaten by raccoons, otters, wading birds, fish and bigger alligators [12]. Florida red-bellied turtles lay their eggs inside alligator nests, and nesting females help build up peat [9]. In the dry season, the water in alligator holes becomes a refuge for wildlife. The animals there are easier for predators to catch, but the Park Service says the value of the refuge outweighs that risk [9]. Take the alligators away and those dry-season pools would no longer be dug and kept open.

Crocodiles. A saltwater crocodile starts life eating insects and crustaceans, then moves up to waterbirds, sea turtles and mammals as big as water buffalo [17]. Its eggs are taken by goannas and feral pigs, and its hatchlings by birds of prey, large fish, freshwater turtles and other crocodiles [17]. In Florida, American crocodile hatchlings are eaten by raccoons, birds and crabs, while adults have no natural predators except people [8]. What happens to an ecosystem when crocodiles disappear is less well documented than the alligator-hole story. Read more in what eats crocodiles, and for the turtles both groups hunt, what animals turtles eat.

How are their nests and babies different?

American alligators build mound nests of soil, plants or debris and stay near them. American crocodiles dig holes or build mounds in sand and earth, often leave, and return near hatching time. In both, the nest’s temperature decides whether the babies are male or female [8][9][12].

Female alligators lay an average of 32 to 46 eggs, which hatch after about 63 to 68 days [12]. American crocodiles lay 20 to 60 eggs and incubate them for about 85 days [8]. Alligator hatchlings are dark with yellow stripes; young American crocodiles are light with dark stripes [11]. Alligator mothers stay with their young, sometimes for two or three years [9]. Adult American crocodiles leave the nest area within a day or two, and the hatchlings fend for themselves [8].

Are alligators and crocodiles endangered?

The American alligator is not: it is listed as Least Concern and is a famous recovery story. Many crocodilians are in trouble, though. Seven of the 25 species assessed are Critically Endangered, including the Chinese alligator and the gharial [21].

IUCN Red List status of key species

Species	Family	IUCN status (year assessed)
American alligator	Alligatoridae	Least Concern (2018)
Chinese alligator	Alligatoridae	Critically Endangered (2017)
Spectacled caiman	Alligatoridae	Least Concern (2016)
American crocodile	Crocodylidae	Vulnerable (2020)
Saltwater crocodile	Crocodylidae	Least Concern (2019)
Nile crocodile	Crocodylidae	Least Concern (2017)
Gharial	Gavialidae	Critically Endangered (2017)

Source: IUCN SSC Crocodile Specialist Group’s table of current Red List categories [21]. The Red List website itself could not be opened directly; the categories (not the years) were cross-checked against the IUCN Red List data published through GBIF.

In Florida, the American crocodile is a conservation success. Listed as endangered in 1975, it has recovered from a few hundred animals to as many as 2,000 adults, and the U.S. Fish and Wildlife Service now lists the Florida population as threatened [10]. The alligator is listed federally as “threatened due to similarity of appearance”, only because it looks so much like the crocodile [13]. The Chinese alligator is far worse off: the Smithsonian says fewer than 150 may remain in the wild [16].

Myths about alligators and crocodiles

Myth: Crocodiles live in the sea and alligators live in fresh water.

Fact: Only partly true. Some crocodiles are freshwater animals, such as the Australian freshwater crocodile, though even it has salt glands [4]. American alligators also turn up in brackish water [12]. Why people believe it: the saltwater crocodile and Florida’s coastal crocodiles are the ones people hear about most.

Myth: Every crocodile has a narrow, pointed snout.

Fact: The saltwater crocodile’s snout is broad [17], and the mugger crocodile’s is almost as broad for its length as an alligator’s [1]. Why people believe it: the U vs V rule is a handy shortcut. The hidden or visible fourth lower tooth is the better test [19].

Myth: A saltwater crocodile bites at 3,700 psi.

Fact: The measured figure is 16,414 N, or 3,689 pounds of force, not psi [1]. Why people believe it: the unit was changed as the number was copied from site to site.

Myth: Run in a zigzag to escape a crocodile or alligator.

Fact: The Crocodile Specialist Group calls this “nonsense”. Crocodilians can burst from the water very fast. The real safety rule is to stay well back from the water’s edge [22]. Why people believe it: it is an old piece of folk advice that sounds clever. See how fast an alligator can run.

Test yourself

1. A crocodilian’s mouth is shut and a big lower tooth shows near the front on each side. Alligator or crocodile?

Crocodile. In alligators and caimans that tooth is hidden in a socket.

2. Where in the world do wild alligators and crocodiles live side by side?

South Florida, in the USA.

3. Why can crocodiles live in salt water when alligators mostly can’t?

Crocodiles have salt glands in the tongue that get rid of extra salt. Alligators lack them.

Alligators and crocodiles have been going their separate ways for something like 90 million years, and the clues are still written on their faces: one tooth, a few thousand tiny sensory dots and a tongue that can or cannot sweat salt. Next time you see one, look at the teeth first. Just do it from a safe distance.

Frequently asked questions

Sources

1. Erickson, G.M. et al. (2012). Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation. PLOS ONE 7(3): e31781.
2. Leitch, D.B. and Catania, K.C. (2012). Structure, innervation and response properties of integumentary sensory organs in crocodilians. Journal of Experimental Biology 215: 4217–4230.
3. Taplin, L.E. and Grigg, G.C. (1981). Salt glands in the tongue of the estuarine crocodile Crocodylus porosus. Science 212: 1045–1047.
4. Taplin, L.E., Grigg, G.C., Harlow, P., Ellis, T.M. and Dunson, W.A. (1982). Lingual salt glands in Crocodylus acutus and C. johnstoni and their absence from Alligator mississipiensis and Caiman crocodilus. Journal of Comparative Physiology B 149: 43–47.
5. Franklin, C.E. and Grigg, G.C. (1993). Increased vascularity of the lingual salt glands of the estuarine crocodile, Crocodylus porosus, kept in hyperosmotic salinity. Journal of Morphology 218: 143–151.
6. Walter, J.D. et al. (2025). Expanded phylogeny elucidates Deinosuchus relationships, crocodylian osmoregulation and body-size evolution. Communications Biology 8: 611.
7. U.S. Geological Survey. Do alligators and crocodiles exist together anywhere in the world?
8. National Park Service, Everglades National Park. American crocodile: species profile.
9. National Park Service, Everglades National Park. American alligator: species profile.
10. Florida Fish and Wildlife Conservation Commission. American crocodiles.
11. Florida Fish and Wildlife Conservation Commission. American crocodile species profile.
12. Florida Fish and Wildlife Conservation Commission. Alligator facts.
13. Florida Fish and Wildlife Conservation Commission (2022). Human-alligator incidents fact sheet.
14. Florida Fish and Wildlife Conservation Commission (updated February 2026). Alligator bites on people in Florida.
15. Smithsonian’s National Zoo & Conservation Biology Institute. American alligator.
16. Smithsonian’s National Zoo & Conservation Biology Institute. Chinese alligator.
17. Australian Museum. Estuarine crocodile.
18. Guinness World Records. Largest crocodile in captivity ever; and (2013) Lolong, the world’s largest crocodile in captivity, dies in the Philippines.
19. IUCN SSC Crocodile Specialist Group. Crocodiles, alligators or gharials?
20. IUCN SSC Crocodile Specialist Group. Crocodilian species (26 species, following Vliet et al. 2024).
21. IUCN SSC Crocodile Specialist Group. Conservation status (current IUCN Red List categories).
22. IUCN SSC Crocodile Specialist Group. Crocodilian attacks (including CrocBITE data, 2010–2020).
23. Meredith, R.W. et al. (2024). Draft assembly and annotation of the Cuban crocodile (Crocodylus rhombifer) genome. BMC Genomic Data 25: 53.
24. Peasah, A. (2025). Can there be alligator-crocodile hybrids? The Tech Interactive, Ask a Geneticist (Stanford University).
25. Florida Fish and Wildlife Conservation Commission. Caiman.
26. Di-Poï, N. and Milinkovitch, M.C. (2013). Crocodylians evolved scattered multi-sensory micro-organs. EvoDevo 4: 19.
27. Bolaños Montero, J.R. et al. (2019). Population status of the American crocodile, Crocodylus acutus, and the caiman, Caiman crocodilus, in the Central Caribbean of Costa Rica. Revista de Biología Tropical 67.

Sources checked 14 October 2026.

Update, 14 October 2026: this article was fully rewritten. We removed claims we could not verify (for example that crocodiles are generally longer and slimmer and that crocodiles nest only on sandy shores), removed an unrelated commercial link, and added sourced figures for size, bite force, attacks and conservation status.