Alligators and crocodiles are often confused, though they belong to two distinct biological families: Alligatoridae and Crocodylidae. Both are part of the ancient order Crocodilia, which includes 28 extant species. This shared lineage explains their similar appearance as large, semi-aquatic predators with powerful jaws and armored bodies. Determining which one grows largest reveals an important difference between the two families.
The Definitive Size Comparison
The crocodile family holds the record for the largest living reptile species on Earth. The American Alligator, the largest alligator species, typically reaches 13 or 14 feet in length and often approaches 1,000 pounds. Exceptional males have been recorded at nearly 16 feet long. Crocodiles, however, demonstrate a capacity for significantly greater maximum dimensions.
The Saltwater Crocodile, found across Asia and Australia, regularly exceeds 17 feet in length. These giants commonly weigh over 2,000 pounds, with verified individuals reaching 20 feet or more. This species represents the upper limit of size among all crocodilians, often being four feet longer and more than double the weight of the largest American Alligators.
Key Physical Distinctions
Several anatomical features allow for the distinction between an alligator and a crocodile. The most noticeable difference is the shape of the snout and how the teeth fit when the mouth is closed. Alligators possess a broad, rounded, U-shaped snout that is wider at the base. This wide upper jaw creates an overbite, concealing all of the lower teeth when the alligator closes its mouth.
Crocodiles, in contrast, have a longer, narrower, and more pointed V-shaped snout. Their upper and lower jaws are nearly the same width, allowing the teeth to interlock when the mouth is shut. This results in a visible “toothy grin,” as several lower teeth protrude outside the upper jawline. The fourth tooth on the lower jaw is particularly noticeable, fitting into a notch on the outside of the upper jaw.
Habitat and Distribution
The global distribution of these two families is different, linked to their physiological ability to manage saltwater. Alligators have a restricted range, with only two extant species: the American Alligator and the much smaller Chinese Alligator. The American Alligator is primarily confined to the southeastern United States, while the Chinese Alligator inhabits the Yangtze River basin.
Crocodiles, conversely, are found across a broader global distribution, including Africa, Asia, Australia, and the Americas. This wider range is due to their functional lingual salt glands. Crocodiles can excrete excess salt from their bodies, allowing them to tolerate brackish and marine environments for extended periods. Alligators lack this mechanism and are mainly restricted to freshwater habitats, though they can occasionally venture into brackish water briefly.