Crocodiles and alligators belong to the ancient order Crocodilia. Though often mistaken for each other due to their similar appearance as large, semi-aquatic reptiles, they represent distinct biological families. Understanding their differences reveals unique adaptations.
Comparing Their Size
The saltwater crocodile (Crocodylus porosus) generally holds the title as the largest living reptile, often surpassing alligators in both length and weight. Adult male saltwater crocodiles typically measure 4.0 to 4.5 meters (13 feet 1 inch to 14 feet 9 inches) and weigh between 408 to 770 kilograms (899 to 1,698 pounds). Very large males can exceed 6 meters (19 feet 8 inches) in length and may weigh up to 2,000 kilograms (4,400 pounds). The largest confirmed saltwater crocodile, named Lolong, measured 6.17 meters (20 feet 3 inches) and weighed 1,075 kilograms (2,370 pounds).
The American alligator (Alligator mississippiensis) is typically smaller. Adult male American alligators commonly range from 3.4 to 4.5 meters (11.2 to 14.8 feet) in length and can weigh up to 500 kilograms (1,100 pounds). Females are smaller, generally measuring 2.6 to 3 meters (8.5 to 9.8 feet). While some American alligators rarely reach 5.84 meters (19 feet 2 inches), such sizes are uncommon. The heaviest American alligator on record weighed 626 kilograms (1,380 pounds) and measured 4.04 meters (13 feet 3 inches).
Key Distinctions
Physical characteristics offer clear ways to differentiate these powerful reptiles beyond their size. One apparent distinction lies in the shape of their snouts. Alligators possess a broad, U-shaped snout, well-suited for crushing prey with hard shells like turtles. Crocodiles typically have a narrower, V-shaped snout, adapted for capturing fish and other agile prey.
Another reliable indicator is the arrangement of their teeth when their mouths are closed. An alligator’s upper jaw is wider than its lower jaw, allowing the lower teeth to fit into sockets within the upper jaw and remain hidden when the mouth is shut. Crocodiles have upper and lower jaws that are nearly the same width, causing some of their lower teeth to be visible and interlock with the upper teeth even when the mouth is closed. Alligators have darker, blackish-grey skin, while crocodiles exhibit lighter, more olive or tan coloration.
Habitats and Geographic Range
Alligators and crocodiles differ in their preferred habitats and geographical distribution. Alligators primarily inhabit freshwater environments, including swamps, marshes, lakes, and slow-moving rivers. They have a limited tolerance for saltwater as they lack the specialized salt glands that crocodiles possess for expelling excess salt. The American alligator is found predominantly in the southeastern United States, from North Carolina to Texas, with significant populations in Florida and Louisiana. A smaller species, the Chinese alligator, resides solely in the Yangtze River valley in China.
Crocodiles display a broader tolerance for salinity and can thrive in various environments, including freshwater, brackish water, and marine habitats. This adaptability is due to functional salt glands located under their tongues. Crocodiles have a more widespread global distribution, found across tropical regions in Africa, Asia, Australia, and the Americas. The American crocodile, for example, is found along coastal areas of South Florida, Central America, and northern South America. The Florida Everglades is a unique location where both American alligators and American crocodiles coexist.