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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Morelet's Crocodile

Synonyms and Other Names: Mexican Crocodile, Alligator (Belize), Cocodrilo del Petén (Guatemala), Lagarto negro, Cocodrilo de pantano (México)

Taxonomy: available through www.itis.gov

Identification: Morelet’s Crocodile is a medium-sized crocodile, dark green to black in color (Platt and Rainwater 2005).

Compared to the sympatric American Crocodile, C. acutus, Morelet’s crocodile has a broader snout, weakly keeled osteoderms (bony deposits forming scales) on the dorsum, and irregular scalation on the ventral surface of the tail (Platt and Rainwater 2005).

Size: Maximum size of males is estimated to be 4.5 m total length, with males rarely attaining >3 m TL and females being 15-20% smaller on average (Platt et al. 2009).

Native Range: Morelet’s Crocodile’s distribution ranges from Belize and Guatemala north through the Yucatan Peninsula into northeastern Mexico (Platt et al. 2010).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Small Morelet’s Crocodile consume primarily insects and arachnids, with aquatic gastropods, crustaceans, fish, amphibians, reptiles, birds, and mammals becoming increasingly important in larger individuals (Platt et al. 2006).

Sexual maturity is attained at approximately 1.5 m TL (Platt et al. 2009). Like many other crocodilians, Morelet’s Crocodile females construct nest of vegetation and soil in which to incubate eggs and that protects both the nest and hatchlings (Platt et al. 2010).

Means of Introduction: The individual captured in Palm Beach County was likely a released pet.

Status: Not established.

Impact of Introduction: While Morelet’s Crocodile is not known to have impacted native species in the United States, it has the potential to impact native crocodilians. Morelet’s Crocodile is a host for several parasites, some of which are generalists that can infect other crocodilian species such as American Crocodile and American Alligator, Alligator mississippiensis (Moravec 2001). Where their native ranges overlap, Morelet’s Crocodile hybridizes with the American Crocodile (Ray et al. 2004; Cedeño-Vázquez et al. 2008; Rodriguez et al. 2008), which is listed as threatened in the United States (US Fish and Wildlife Service, 2007). If they were to become established in Florida, Morelet’s Crocodile could compete with the American Crocodile for food and space (Metzger et al. 2020).

Remarks: Morelet’s Crocodile is listed under CITES Appendix 1 in Guatemala, and Appendix II in Belize and Mexico (Platt et al. 2010).

References: (click for full references)

Cedeño-Vázquez, J.R., D. Rodriguez, S. Calmé, J.P. Ross, L.D. Densmore, and J.B. Thorbjarnarson. 2008. Hybridization between Crocodylus acutus and Crocodylus moreletii in the Yucatan Peninsula: I. Evidence from mitochondrial DNA and morphology. Journal of Experimental Zoology A 309(10):661-673.

Dever, J.A., R.E. Strauss, T.R. Rainwater, S.T. McMurry, and L.D. Densmore III. 2002. Genetic diversity, population subdivision, and gene flow in Morelet's Crocodile (Crocodylus moreletii) from Belize, Central America. Copeia 2002(4):1078-1091.

Metzger III, E.R., M.R. Rochford, A.M. Lawrence, and F.J. Mazzotti. 2020. Morelet’s Crocodile, Crocodylus moreletii (Duméril & Bibron 1851) (Crocodylidae), another nonnative crocodilian species introduced to Florida, USA. IRCF Reptiles & Amphibians 26(3):259-260.

Platt, S.G., L. Sigler, and T.R. Rainwater. 2010. Morelet’s Crocodile Crocodylus moreletii. Pages 79-83 in S.C. Magnolis and S. Stevenson, eds. Crocodiles. Status survey and conservation action plan. Third edition. Crocodile Specialist Group. Darwin, Australia.

Platt, S.G., and T.R. Rainwater. 2006. A review of morphological characters useful for distinguishing Morelet’s crocodile (Crocodylus moreletii) and American crocodile (Crocodylus acutus) with an emphasis on populations in the coastal zone of Belize. Bulletin of the Chicago Herpetological Society 40(2):25-29.

Platt, S.G., T.R. Rainwater, A.G. Finger, J.B. Thorbjarnson, T.A. Anderson, and S.T. McMurry. 2006. Food habits, ontogenetic dietary partitioning and observations of foraging behaviour of Morelet's crocodile (Crocodylus moreletii) in northern Belize. The Herpetological Journal 16(3):281-290.

Platt, S.G., T.R. Rainwater, J.B. Thorbjarnarson, A.G. Finger, T.A. Anderson, S.T. McMurry. 2009. Size estimation, morphometrics, sex ratio, sexual size dimorphism, and biomass of Morelet's crocodile in northern Belize. Caribbean Journal of Science 45(1):80-93.

Ray, D.A., J.A. Dever, S.G. Platt, T.R. Rainwater, A.G. Finger, S.T. McMurry, M.A. Batzer, B. Barr, P.J. Stafford, J. McKnight, and L.D. Densmore. 2004. Low levels of nucleotide diversity in Crocodylus moreletii and evidence of hybridization with C. acutus. Conservation Genetics 5:449-462.

Author: Freedman, J.A.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.