Alligator snapping turtle

AlligatorSnapper.jpg

Alligator snapping turtle: Macrochelys temminckii

Taxonomic Classification

Kingdom: Animalia

Phylum: Chordata

Class: Chelonia

Order: Testudines

Family: Chelydridae

Genus/Species: Macrochelys temminckii

Common Name: Alligator snapping turtle

Listing Status

Federal Status: Under Review

FL Status: State Species of Special Concern

FNAI Ranking: G3G4/S3 (Globally: Insufficient Date but ranges from Rare to Apparently Secured/State: Rare)

IUCN Ranking: VU (Vulnerable)

Physical Description

The alligator snapping turtle is the largest freshwater turtle in North America.  Male alligator snapping turtles can reach lengths of 29 inches (73.7 centimeters) and 249 pounds (112.9 kilograms), while females can reach lengths of 22 inches (55.9 centimeters) and 62 pounds (28.1 kilograms)  (Ewert et al. 2006, Pritchard 2006).  The inner mouth lining is gray/brown with black splotches, which is different from most turtles; others have a pink lining (Ewert et al. 2006).  This species also has a tremendously long tail; large, triangle-shaped head; curved beak; and a rough brown shell with three spines that run vertically up the shell (Florida Natural Areas Inventory 2001). 

Life History

The diet of the alligator snapping turtle primarily consists of different plants and animals such as fish, musk turtles, and acorns (Pritchard 1992). 

Courting occurs from February to April, with nesting occurring from late April into the middle part of May in western Florida.  This species prefers to construct their nests in sandy soils within 65.6 feet (20 meters) of water, although they sometimes construct the nests as far as 656 feet (200 meters) from water.  Females prefer to nest when the weather is warm and humid, which is when they will lay an average of 17-52 eggs in a clutch, with one clutch being laid per year (Allen and Neill 1950, Dobie 1971, Ewert et al. 2006, Ewert and Jackson 1994).  Eggs are incubated for 100-110 days with most eggs hatching in mid-August (Ewert and Jackson 1994).  The sex of the offspring is determined by the surrounding environmental temperature of the egg.  An incubation temperature of 77-80.6°F (25-27°C) will result in a male hatchling, and a temperature of 84.2-86°F (29-30°C) will result in a female hatchling (Ewert et al. 2006).  Alligator snapping turtles reach sexual maturity at 11-13 years of age (Smithsonian National Zoological Park, n.d.).

Habitat and Distribution

Alligator Snapper Distribution MapThe alligator snapping turtle can be found in rivers, lakes, backwater swamps, and periodically in brackish water systems (mixture of fresh and salt water) from Florida to Texas and north to Illinois (Florida Natural Areas Inventory 2001).  In Florida, this species can be found in the Panhandle and Big Bend regions, from the Escambia River east to the Suwannee River (Ewert et al. 2006, Pritchard 2006, Map Data from: Krysko et al. 2011).

Threats:

Alligator snapping turtles were historically used as food in their southern range; the highest amount of harvesting occurred in the 1960s and 1970s, which caused regional population declines (Reed et al. 2002).  Mortality rates slowed in the 1970s in Florida when the Florida Game and Fresh Water Fish Commission (now the Florida Fish and Wildlife Conservation Commission) enacted rules to limit the take of alligator snapping turtles.  Presently, under Rule 68A-27.005 External Website of the Florida Administrative Code, it is illegal to take, possess, or sell the alligator snapping turtle, as it is a protected species.  It could take decades for the alligator snapping turtle to recover from the pre-1970 overharvesting.  Bycatch (organisms caught in fish nets that are not wanted) mortality on lines set for fish, especially catfish, is a present threat to the alligator snapping turtle.  Included in these lines are both trot lines (long lines of submerged baited hooks) and bush lines (single hooks suspended from tree branches) (Ewert et al. 2006, Pritchard 2006).  Chemical pollution from industry and farms are a threat to all riverine species, even though a spill in one river would not endanger the species statewide (Ewert et al. 2006).  Siltation from road crossings could potentially reduce the quality of smaller streams utilized by this species, such as the clear seepage streams on Eglin Air Force Base.  Natural threats include the possible increased predation on their eggs from raccoons, wild hogs, and red imported fire ants.

Conservation and Management

The alligator snapping turtle is protected as a State Species of Special Concern by Florida’s Endangered and Threatened Species Rule External Website.  The alligator snapping turtle is currently under review for Federal listing by the USFWS.

Other Informative Links

Florida Natural Areas Inventory Adobe PDF External Website

International Union for Conservation of Nature External Website

Smithsonian National Zoological Park External Website

U.S. Geological Survey External Website

 

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References

Allen, E. R., and W. T. Neill.  1950.  The alligator snapping turtle Macrochelys temminckii in Florida.  Ross Allen's Reptile Institute Special Publication 4:1-15.

Dobie, J. L.  1971.  Reproduction and growth in the alligator snapping turtle Macroclemys temminckii (Troost).  Copeia 1971:645-658.

Ewert, M. A., and D. R. Jackson.  1994.  Nesting ecology of the alligator snapping turtle  (Macroclemys temminckii) along the lower Apalachicola River, Florida.  Florida Game and Freshwater Fish Commission, Nongame Wildlife Program Report NC89-020, Tallahassee, Florida. 45pp.

Ewert, M. A., D. R. Jackson, and P. E. Moler.  2006.  Macrochelys temminckii – alligator  snapping turtle.  Pages 58–71 in P. A. Meylan, editor.  Biology and conservation of      Florida turtles.  Chelonian Research Monographs No. 3.

Florida Natural Areas Inventory.  2001.  Field guide to the rare animals of Florida. http://www.fnai.org/FieldGuide/pdf/Macroclemys_temminckii.PDF Adobe PDF External Website

Krysko, K., K. Enge, and P. Moler. 2011. Macrochelys temminckii complex (Troost in Harlan 1835) Alligator Snapping Turtle. Atlas of Amphibians and Reptiles in Florida.

Pritchard, P.C.H. 1992.  Alligator snapping turtle, Macrochelys temminckii Harlan. Pages 171-177 in P. E. Moler, editor.  Rare and endangered biota of Florida. Volume III.   Amphibians and Reptiles.  University Press of Florida, Gainesville, Florida, USA.

Pritchard, P. C. H.  2006.  The alligator snapping turtle: biology and conservation.  Second edition.  Krieger Publishing Company, Malabar, Florida, USA. 140pp.

Reed, R. N., J. D. Congdon, and J. W. Gibbons.  2002. The alligator snapping turtle (Macroclemys [Macrochelys) temminckii]: a review of ecology, life history, and Alligator Snapping Turtle Biological Status Review Report 8)

Smithsonian National Zoological Park.  (n.d.).  Alligator Snapping Turtle.  Retrieved 23 February, 2011, from Smithsonian National Zoological Park Friends of the National Zoo: http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Alligatorsnappingturtle.cfm External Website


Image Credit Kevin Enge, FWC



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