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Native and Nonnative Crocodilians of Florida

Michiko A. Squires, Seth C. Farris, Brian M. Jeffery, and Frank J. Mazzotti

Florida has two native species of crocodilians, the American alligator (Alligator mississippiensis) and the American crocodile (Crocodylus acutus). These federally protected species are easily confused with nonnative crocodilians found in south Florida, such as the spectacled caiman (Caiman crocodilus) and the Nile crocodile (Crocodylus niloticus). Some key features used to distinguish these animals are the shape of the head, the shape of the snout, and the pattern of nuchal scutes (bony plates in between head and shoulders). It is important to report all nonnative crocodilians so that researchers may quickly remove them in order to protect Florida's native ecosystems.

If you see a nonnative crocodilian:

  1. Take a photograph
  2. Note the location
  3. Report your sighting by calling 1-888-IVE-GOT1, visiting http://www.IveGot1.org or by using the IveGot1 smartphone app (available for free at the iPhone App Store and Android Market).

All crocodile sightings (native and nonnative) should also be reported to University of Florida by calling (954) 577-6304.

American Alligator (Alligator mississippiensis) – NATIVE

Very common in Florida; not necessary to report. Snout is much more broad and rounded than that of crocodiles; only the top row of teeth is visible when the mouth is closed. Adults are a dark, dusky olive-black color.

Figure 1. Alligator head.
Figure 1.  Alligator head.
Credit: Brian Jeffery, UF/IFAS

 

Figure 2. Alligator.
Figure 2.  Alligator.
Credit: Brian Jeffery, UF/IFAS

 

Spectacled Caiman (Caiman crocodilus) – NONNATIVE

Please report to IveGot1! Similar to the American alligator but with a triangular head and slightly more pointed snout. "Spectacle" ridge on the snout in front of eyes. Dark brown or olive coloration.

Figure 3. Spectacled caiman head.
Figure 3.  Spectacled caiman head.
Credit: Joe Wasilewski, Natural Selections of South Florida,Inc.

 

Figure 4. Spectacled caiman.
Figure 4.  Spectacled caiman.
Credit: Mike Rochford, UF/IFAS

 

Crocodiles of South Florida

Crocodiles (Figure 5) are sometimes confused with alligators (Figure 6), however they are easily distinguishable by comparing their heads/snouts. Crocodiles have a pointed, narrow snout and their bottom teeth are visible when the mouth is closed. Alligators have a rounded, blunt snout and only the top teeth are visible when the mouth is closed.

Figure 5. American crocodile head.
Figure 5.  American crocodile head.
Credit: Jemeema Carrigan, UF/IFAS

 

Figure 6. American alligator head.
Figure 6.  American alligator head.
Credit: Jemeema Carrigan, UF/IFAS

 

American Crocodile (Crocodylus acutus) - NATIVE

Please report to University of Florida. Narrow, pointed snout; fourth tooth on bottom row is visible when the mouth is closed. Irregular pattern of nuchal scutes (bony plates in between head and shoulders). Dark olive-brown and dark olive-green.

Figure 7. American crocodile head.
Figure 7.  American crocodile head.
Credit: Brian Jeffery, UF/IFAS

 

Figure 8. American crocodile.
Figure 8.  American crocodile.
Credit: Eric Zamora, UF/IFAS

 

Nile Crocodile (Crocodylus niloticus) – NONNATIVE

Please report to IveGot1 and University of Florida! Very difficult to distinguish from the American crocodile. Narrow, pointed snout (slightly more broad than an American crocodile). Symmetrical pattern of osteoderms (bony plates on the back). Dark olive-brown or dark gray. Not commonly found in south Florida.

Figure 9. Nile crocodile (Crocodylus niloticus).
Figure 9.  Nile crocodile (Crocodylus niloticus).
Credit: Joe Wasilewski, Natural Selections of South Florida,Inc.

 

Figure 10. Nile crocodile.
Figure 10.  Nile crocodile.
Credit: Rhett Butler, Mongabay