Alligator or crocodile? How to tell the American alligator apart

The American alligator is a recovered species, and yet the federal government still lists it as threatened. The reason, according to the Smithsonian’s National Zoo, is that it closely resembles the American crocodile. In other words, an animal is still carrying a legal label mostly because people have a hard time telling it from its cousin.

So how do you tell them apart? Four checks work in the field: snout, teeth, color and habitat. This article tests each one against what the National Park Service and other sources say, shows where each rule of thumb fails, and keeps its focus on the American alligator (Alligator mississippiensis). Treat it as a guide to watching from a distance, not to getting closer. These are large wild animals, and this article is not a guide to approaching or handling them.

Meet the American alligator

The numbers below come from the Smithsonian’s National Zoo, the National Park Service (NPS) and the U.S. Fish and Wildlife Service (FWS).

That growth row is easy to skim past. A baby alligator adds about a foot a year for its first few years, which is the kind of progress most of us stop seeing after middle school.

Four checks, side by side

Here is how the American alligator compares with the American crocodile, the species most often confused with it in the United States.

Snout. An alligator’s snout looks like a wide U and a crocodile’s like a pointed V, according to PBS. NPS describes the alligator’s snout as broad and the crocodile’s as narrow and triangular.

Teeth. This is the favorite trick of park rangers and trivia nights alike. The Zoo explains that the large fourth tooth in an alligator’s lower jaw fits into a socket in the upper jaw and stays hidden when the mouth is closed. In crocodiles that tooth stays visible, and NPS says the fourth tooth on each side of the lower jaw shows. A handy way to remember it: usually one visible row of teeth points to an alligator, and two rows point to a crocodile. Stay well back while you count.

Color. NPS says algae-laden water can make an alligator look greener, and tannic acid from overhanging trees can make it darker. So the “alligators are darker” rule is a hint, not a test.

Salt water: the habitat clue

Why do crocodiles cope with the sea while alligators mostly do not? The Zoo says alligators tolerate salt water only briefly because they lack salt glands. NPS agrees that alligators lack the salt-secreting glands crocodiles have. PBS says crocodiles have special glands that help them tolerate salt. A University of Florida extension article words it a little differently, saying the relevant glands are not well developed in alligators. It names them as lachrymal glands, which sit near the eye, but we could not confirm that against the Zoo or Park Service pages, which do not name the gland, so we leave that detail out of our own claims. The article adds that their skin is impermeable to seawater, but thinner areas let some in, and they can swallow it, so they cannot tolerate seawater for long and must eventually return to fresh water. The sources differ on whether the glands are absent or weak, and agree on the result.

So seeing a large reptile in brackish water near mangroves does not settle the question. NPS says alligators can briefly tolerate brackish water there.

What this looks like in practice

Use this as a field checklist, and do it with binoculars or a zoom lens.

• Where am I? Alligators range from North Carolina to central Texas. In Florida, NPS says crocodiles live in coastal south Florida, where alligators are more numerous.
• Snout: wide and rounded, or narrow and pointed?
• Teeth: with the mouth shut, do you see one row or two, and is that fourth lower tooth showing?
• Water: fresh, or brackish and salty?
• Color: use it last and treat it as a weak hint.
• Distance: stay far back. The checklist works fine from a distance.

A worked example: a dark reptile with a wide, rounded snout lies in a freshwater marsh in the Southeast, and no lower teeth show with its mouth closed. Every check points the same way, so it is an American alligator. The checks only become tricky when they disagree.

Common mistakes and mix-ups

Mix-up: color settles it. Alligators tend to be darker and crocodiles lighter, but algae and tannic acid can shift an alligator’s color.

Myth: the bigger reptile is the crocodile. NPS says male American crocodiles can reach about 20 feet but rarely exceed 14 feet in the wild, while alligator males occasionally reach 13 to 15. In the United States, size alone can mislead. The biggest crocodile species is another story: PBS says the saltwater crocodile passes 20 feet and 2,000 pounds. Crocodiles live across Africa, Asia, Australia and parts of the Americas, and two of them have articles here, the Nile crocodile and the Saltwater crocodile.

Myth: crocodiles live only in salt water. PBS says they live in both fresh and salt water.

Myth: alligators live only in Florida. The Zoo’s range runs from North Carolina to Texas. PBS adds that alligators live mainly in the southeastern United States and China, where a smaller species, the Chinese alligator, lives in the east of the country.

Mix-up: the snout rule covers every crocodile relative. The order that includes alligators and crocodiles also contains caimans and gharials, according to PBS. The Gharial has its own article and its own very different snout.

Conservation status

The American alligator is listed as Least Concern on the IUCN Red List of Threatened Species. That is the category as distributed by GBIF, the Global Biodiversity Information Facility, and we checked it on November 9, 2026. Least Concern means the species was evaluated and does not meet the criteria for a threatened or near-threatened category.

That is a comeback story with fine print. NPS says hunting and habitat loss reduced populations, the species was listed as endangered in 1967, and hunting bans and later changes to hide-movement laws helped it recover. It came off the endangered list in 1987. The Zoo says the species nearly went extinct, has recovered remarkably, and is no longer endangered except in scattered areas, yet the federal government still lists it as threatened because it closely resembles the American crocodile. The Zoo calls the crocodile endangered, while NPS says the Florida crocodile population has been reclassified as threatened and the worldwide population is still listed as endangered. The Zoo adds that hunting is allowed in some states under strict control and that the greatest current threat is habitat destruction, including water management systems and mercury and dioxin in the water. Neither source gives a current population number, so we have no confirmed trend beyond the reported recovery.

Categories are reviewed and can change, and the copy GBIF distributes can trail the IUCN website by some months, which is why we print the date we checked. GBIF’s copy does not give the year of the assessment, so we do not state one.