The Florida Keys create a unique environment where two of the world’s largest reptiles—the American Alligator and the American Crocodile—can be found. While large crocodilians are present across the Keys, the species most commonly encountered is the crocodile. Alligators do inhabit the Keys, but their presence is extremely limited compared to the vast populations found across the Florida mainland. This overlap makes the Keys a singular location globally where both species naturally coexist.
Alligator Presence and Limited Habitat
The American Alligator is a reptile adapted primarily to freshwater ecosystems, a requirement that severely restricts its range within the highly saline Florida Keys. These animals lack the specialized salt glands that allow crocodiles to excrete excess salt, meaning they must regularly access fresh water to survive long-term. This physiological need makes the vast majority of the Keys, which are surrounded by ocean, unsuitable habitat.
The few alligators that reside in the Keys are typically found in the northernmost islands, such as Key Largo. This area is closest to the freshwater marshes of the Everglades and contains more pockets of brackish or permanent fresh water, often in man-made canals or quarry pits. A small population also exists in the Lower Keys, notably on Big Pine Key, where protected freshwater habitats are managed. Their rarity is a direct consequence of the lack of consistent, low-salinity water sources.
The Abundant American Crocodile
The American Crocodile is the dominant crocodilian species throughout the Florida Keys. This species thrives in the Keys because it is a euryhaline reptile, meaning it is highly tolerant of saltwater and brackish conditions. Specialized salt glands on the tongue allow the crocodile to process and excrete the excess salt, a capability the alligator lacks.
The northern Keys, particularly Key Largo, serve as a significant hub for this species, including the Crocodile Lake National Wildlife Refuge. The refuge was established to safeguard the crocodile’s breeding and nesting habitat. The species has recovered significantly since being listed as endangered, and its status in Florida has since been downgraded to threatened, with an estimated population of up to 2,000 adults.
Crocodiles are regularly seen in the mangrove swamps, coastal lagoons, and saltwater canals. They are generally reclusive and prefer to avoid human interaction. The Keys environment provides an ideal blend of warm, subtropical climate and necessary estuarine habitat to sustain a stable population.
Telling Them Apart and Safety Guidelines
Distinguishing between the two species is possible by focusing on a few easily observable physical differences. The American Alligator has a broad, rounded, U-shaped snout, which gives its head a more blunt appearance. Conversely, the American Crocodile possesses a more slender, pointed, V-shaped snout.
Another way to tell them apart involves looking at their teeth when their mouths are closed. The upper jaw of the alligator completely overlaps the lower jaw, so only the upper teeth are visible along the jawline. The crocodile’s upper and lower jaws are nearly the same width, causing the fourth tooth on the lower jaw to protrude and be clearly visible outside the upper jaw.
Safety guidelines must be followed when near crocodilians. Never feed these reptiles, as doing so encourages them to lose their natural fear of humans and associate people with food.
Safety Guidelines
- Maintain a respectful distance from any crocodilian.
- Never feed the reptiles.
- Keep pets and small children away from the water’s edge.
- Be cautious near canals, ponds, and mangrove areas where the animals may be resting.