Differences between Alligator and Crocodile

Alligator vs. Crocodile

Alligators and crocodiles are large, semi-aquatic reptiles belonging to the order Crocodilia. While they share many physical characteristics, they belong to separate biological families—Alligatoridae and Crocodylidae, respectively. Key distinctions between them can be observed in their snout shape, tooth alignment, habitat, and physical sensory organs. Though their ranges are largely separate, South Florida is the only region in the world where both alligators and crocodiles coexist in the wild.

Comparison Table

Category	Alligator	Crocodile
Snout Shape	Wide, U-shaped snout, effective for crushing hard-shelled prey.	Narrow, V-shaped snout, suited for catching fish.
Tooth Visibility	Upper jaw is wider than the lower jaw, so lower teeth are hidden when the mouth is closed.	Upper and lower jaws are similar in width, causing teeth to interlock and remain visible when the mouth is closed. The large fourth tooth on the lower jaw is particularly noticeable.
Habitat	Almost exclusively found in freshwater environments like swamps, rivers, and lakes.	Tolerates saltwater due to specialized salt glands and often lives in brackish water, estuaries, and coastal mangroves.
Coloration	Typically dark gray or black.	Generally lighter shades of olive green or brown.
Sensory Organs	Integumentary sense organs (ISOs), which detect pressure changes, are concentrated around the jaws.	ISOs are distributed across the entire body. These appear as small pores on the scales.
Geographic Range	Found only in the southeastern United States and eastern China.	Found across tropical regions in Africa, Australia, Asia, and the Americas.

Venn diagram comparing Differences between Alligator and Crocodile

Physical Differences

The most direct way to distinguish between an alligator and a crocodile is by the head shape. Alligators have a broad, U-shaped snout that provides significant crushing force, useful for prey such as turtles. Crocodiles possess a more slender, V-shaped snout.

Dental arrangement is another clear indicator. In alligators, the wider upper jaw covers the lower teeth when the mouth is shut. Crocodiles' upper and lower jaws are roughly the same width, causing their teeth to interlock, with many lower teeth visible. The large fourth tooth on a crocodile's lower jaw is a reliable feature, as it rests in a constriction on the outside of the upper jaw and is clearly visible.

Both reptiles have integumentary sense organs (ISOs), which appear as small dots on their scales and are used to detect pressure changes in the water. On alligators, these sensors are located on the head around the jaws. Crocodiles have these sensory pores distributed over their entire bodies.

### Habitat and Behavior Habitat preference is a significant factor separating the two groups. Alligators primarily inhabit freshwater environments. Crocodiles have functional salt glands on their tongues that excrete excess salt, allowing them to tolerate and often prefer saltwater or brackish coastal habitats.

In terms of temperament, crocodiles are generally regarded as more aggressive than alligators. Alligators tend to be less confrontational and may avoid humans, whereas some crocodile species are known to be more territorial and potentially dangerous.