Toothy old-timers: Alligators & Crocodiles

Florida’s waterways hide wondrous, ancient creatures. Crocodilians — alligators, crocodiles, caimans and gharials — inhabit tropical and warm-temperate lowlands in Africa, Asia, Australia and the Americas.

Human impacts threaten many crocodilians, but conservation and science-driven management can help these old-timers survive and continue their valuable “jobs,” as top predators in their ecosystem.

Thank you to our exhibit sponsor!

Two's company,
four's a crowd

American alligators and American crocodiles aren’t the only crocodilians enjoying Florida’s sunshine. Nonnative spectacled caimans and Nile crocodiles in Florida should be reported to: www.ivegot1.org

Here's how to recognize all four.

American AlligatorAlligator mississippiensis

Native
Coloring

Adults black/dark dark grey, brown tones on the back, yellow-white bellies.

Facial Features

Broader, round snout; lower teeth not visible in closed mouth.

American CrocodileCrocodylus acutus

Native
Coloring

Olive or lighter shade of brown / tan

Facial Features

Narrower, pointed snout; fourth lower tooth visible in closed mouth; irregular pattern of bony plates between shoulders and head.

Spectacled Caiman / Common CaimanCaiman crocodilus

Nonative

Invasive breeding populations in areas of Broward and Dade counties.

Coloring

Olive/deep brown

Facial Features

Resembles American alligator, but slightly pointier, more triangular head; ridge in front of eyes.

Nile CrocodileCrocodylus niloticus

Nonative

Nonnative; a few reported in south Florida; no established population, but more research is suggested.

Coloring

Dark olive-green/brown

Facial Features

Looks like American crocodile, but slightly broader snout and regular pattern of bony plates on back.

Stealthy, strong, submerged

Crocodilians thrive in wetland environments using many adaptations, or survival tools. Their tough skin and osteoderms — bone-plated scales on their back and sides — protect against injury and attack and absorb heat. Their greenish, brownish or black skin provides camouflage.

Crocodilians in a human world

Crocodilians are naturally tough, but they needed new armor – including conservation laws and careful management – to survive the age of humans. Crocodilians have been threatened by historical overhunting, habitat loss, and pollution.

Mote scientist Melissa Bernhard studied chemicals called endocrine disruptors and their possible effects on biological signaling in alligators’ bodies. She cautions that the more contaminants in the environment, the greater risk of harm to crocodilians, such as changes in sexual development and reproduction.

Experience The Teeth Beneath and learn more about these amazing animals.
#MoteTeeth

Sources Sketches and illustrations by Shannon Cummings

Paid for in-part by Sarasota County Tourist Development Tax Revenues

  • Professional reviewers: Melissa Bernhard from Mote (did past work on alligators) and her colleagues from other institutions, including Allan Woodward from FWC.
  • American Crocodile: species profile. (2016, November 8). Retrieved from: https://www.nps.gov/ever/learn/nature/crocodile.htm Info on: species range, differentiating from other crocodilians, appearance, feeding, behavior, survival issues, and more.
  • Mazzotti, F. J., and Cherkiss, M. S. (2003). Status and Conservation of the America n Crocodile in Florida: Recovering an Endangered Species While Restoring an Endangered Ecosystem. University of Florida, Ft. Lauderdale Research and Education Center Technical Report. Retrieved from: https://www.nps.gov/ever/learn/nature/upload/MON97-7FinalReportSecure.pdf Info on: threats to survival and conservation actions for the American crocodile; crocodiles as a flagship species for protecting estuaries; crocodile conservation connected to water flow; types of habitats and geographic range that crocodiles inhabit; management of the species in Florida; human-crocodile interactions…
  • Alligator Facts. (2016, November 8). Retrieved from: http://myfwc.com/wildlifehabitats/managed/alligator/facts/ Brief info on multiple alligator topics with Florida focus, such as diet, size, range, conservation status, reproduction and thermoregulation. Includes interesting section/link with adaptations info.
  • Differences Between Crocodiles and Alligators. (2016, November 8). Retrieved from: http://myfwc.com/wildlifehabitats/managed/american-crocodile/croc-or-gator/ Succinct table with key differences, including illustrative photos. Since this is a government agency website, FWC, we could presumably ask for pictures posted there or here for possible use in our exhibit.
  • Squires, M. A. Farris, S. C., Jeffrey, B. M., and Mazzotti, F. J. (2013). Native and Nonnative Crocodilians of Florida. WEC335, one of a series of the Wildlife Ecology and Conservation Department, UF/IFAS Extension. Retrieved from: http://edis.ifas.ufl.edu/uw380 Differences among four species in Florida, the native American alligator and American Crocodile, along with the nonnative spectacled caiman and Nile crocodile.
  • American Alligator: Alligator mississippiensis. (2008). Retrieved from: https://www.fws.gov/endangered/esa-library/pdf/alligator.pdf Details about alligator population decline and recovery; description and diet; breeding and life history; biological role.
  • Classification of Living Crocodilians. (2016, November 8). Retrieved from: http://www.iucncsg.org/pages/Classification-of-Living-Crocodilians.html Lists 24 species in three families within class Crocodilia.
  • Ross, J. P., and Wermuth, H. F. (2016, November 8). Crocodile. Encyclopaedia Britannica. Retrieved from: https://www.britannica.com/animal/crocodile Mentions 23 Crocodilian species (different from above). General characteristics of crocodilians; distribution (broadly, not just Florida); natural history; behavior; clip of alligator vocalization (bellowing); anatomy & physiology; breeding; adaptations; evolution and classification. I haven’t read it all, but I assume most of it is broad and focused on Crocodilians as a class, rather than any single species in depth. Not sure.
  • Nonnatives - Spectacled Caiman. (2016, November 9). Retrieved from: http://myfwc.com/wildlifehabitats/nonnatives/reptiles/spectacled-caiman/ Very basic info on where it’s from, how it has invaded Florida, what it looks like and why it’s a concern.
  • Common Caiman. (2016, November 9). Retrieved from: https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=222 More detailed and more recent information about where common caimans (same sci name as spectacled caimans) have invaded, as late as 2007-2009 in Florida. Invaded areas and impacts beyond Florida. Impacts of invasions.
  • Spectacled Caiman. (2016, November 9). Retrieved from: http://www.arkive.org/spectacled-caiman/caiman-crocodilus/ Biology/behavior, life history, feeding, appearance/size, habitat, conservation status, hunting and pet trade.
  • More resources on various crocodilians - IUCN Crocodile Specialist Group: http://www.iucncsg.org/ ; http://www.iucncsg.org/pages/Species-Accounts.html
  • Adaptations. (2016, November 8). Retrieved from http://bioweb.uwlax.edu/bio203/s2007/schreibe_bran/adaptations.htm

Information on the adaptations on crocodilians.

Biology/behavior, life history, feeding, appearance/size, habitat, conservation status, adaptations

Biology/behavior, life history, feeding, appearance/size, habitat, conservation status,

adaptations

Biology/behavior, life history, feeding, appearance/size, habitat, conservation status,

adaptations

Information specifically pertaining to crocodilians nictitating membrane.

Information specifically pertaining to the lacrimal glands and the nictitating membrane

Crocodiles facts and pictures. Facts about biology.

All about crocodilians adaptations.

Information specifically about the bite force of crocodiles

Information about alligators tendency to undergo torpor during the winter months.

Information regarding the bite force strength between crocodiles and alligators.

  • Rice, A. N. (2004). Diet and condition of American alligators (Alligator mississippiensis) in three central Florida lakes: A thesis presented to the graduate school of the University of Florida. Retrieved from: http://myfwc.com/media/310266/Alligator-Rice-A.pdf Discusses how American alligators are opportunistic predators, whose diet may vary depending on the location and the condition of the habitat. Specifically focuses on gators in Lake Apopka, Lake Griffin and Lake Woodruff in central Florida. Discusses prey types and body condition, but acknowledges that prey may not be the only factor in body condition and/or population success.
  • Alligators and Crocodiles. (2016, November 10). Retrieved from: http://edis.ifas.ufl.edu/topic_alligators Links on the University of Florida website to multiple resources that might help. Includes links about human-alligator relationship and conflict, along with alligators as indicator species for Everglades restoration.
  • Swiman, E., Hostetler, M., Main, M., Miller, S. W. (2005). Living with Alligators: A Florida Reality. WEC203, one of a series of the Wildlife Ecology and Conservation, UF/IFAS Extension. Retrieved from: http://edis.ifas.ufl.edu/uw230 Includes “How can I stay safe around alligators?” Gives FWC number to report nuisance gators. Also, common misconceptions about alligators.
  • Ober, H.K., Dutton, H.J., Woodward, A.R., Hord, L.J. and Giuliano, W.M. Giuliano. (2014). Managing Conflicts with Wildlife: Living with Alligators. WEC348, one of a series of the Wildlife Ecology and Conservation Department, UF/IFAS Extension. Retrieved from: http://edis.ifas.ufl.edu/uw393 Lists specific concerns/risks around alligator interactions and how to decrease risk.
  • Martin, S. (2008). Global diversity of crocodiles (Crocodilia, Reptilia) in freshwater. Hydrobiologia, 595:1. Retrieved from: http://rd.springer.com/article/10.1007/s10750-007-9030-4 Notes that, despite some crocodilian species like the spectacled caiman and Nile Crocodile having broader distributions, most crocodilian species have restricted ranges, and that has been one factor leading to their endangered status in many cases. “Half of the existing crocodilian species are considered either as being endangered or threatened according to the Red List criteria of the World Conservation Union IUCN.”
  • Livingston S. (2016) Man-eating monster crocodile may be Florida’s newest invasive species. University of Florida News. Retrieved from: http://news.ufl.edu/articles/2016/05/man-eating-monster-crocodile-may-be-floridas-newest-invasive-species.php UF news story based upon a journal article describes UF’s finding of a few nonnative Nile crocodiles in south Florida in recent years.
  • Florida Fish and Wildlife Conservation Commission Alligator Bites on People in Florida (September 2016). Retrieved from: http://myfwc.com/media/310203/Alligator-GatorBites.pdf Lists numbers and information about unprovoked gator bites in Florida up to September 2016. Provides number for the Statewide Nuisance Alligator Program: 1-866-FWC-GATOR (392-4286).
  • McNabb, B.K.(2002). The Physiological Ecology of Vertebrates: A View From Energetics.Ithaca, NY : Cornell University Press

A lot of good information about the biological processes that occur within vertebrates including crocodilians.

  • Huchzermeyer, F.W. (2003). Crocodiles: Biology, Husbandry and Diseases.Cambridge, MA:Cabi publishing

General information about the biology and caretaking practices for maintaining

Crocodile habitats

General information about Crocodile behavior and history

Discusses fossil record of Alligator species in Florida. Includes mention of fossils 2 million years old.