IDENTIFICATION:  15-29 inches (38-71  cm). This is the largest species of freshwater turtle occurring the western hemisphere and some captive specimens exceed 250 pounds (113 kg). To date the largest known documented wild caught adult male weighed 175 pounds (80 kg).  He was recovered from Louisiana Poachers of Sulfur, Louisiana by federal wildlife agents. The poachers working in conjunction with Ms. Viola Guidry had taken the large male along with dozens of other large males from Toledo Bend Reservoir. The largest female to date was captured in Tarrant County and weighed 70 pounds (31.7  kg).  Unlike its relative the common snapping turtle, Macrochelys has a short neck bedecked with several fleshy tubercles, an enormous head, highly serrated carapace and 3-5 supra-marginal scutes along the bridge and a strongly curved beak.  The eyes are surrounded by a series of fleshy tubercles often creating the appearance of a star-like pattern and the iris has 6-7 radiating dark lines some of which make contact with the pupil. The interior of the mouth is drab often matching the color of the flesh. On the end of the tongue is small and bifurcated lure that can vary from drab tones of gray to bright pink. It is twitched and moved in a manner that entices fish into its mouth.  No other living species of turtle possesses such a tongue. However, like the common snapping turtle the plastron is reduced and cruciform in appearance. The basal coloration of the carapace is chestnut to drab brown. The head, neck, limbs and tail are drab olive to dark tan. In older specimens the head tends to lighten in coloration ranging from beige to ivory with a cream colored spot near the tympanum.

GEOGRAPHIC DISTRIBUTION:  The alligator snapping turtle occupies a geographic range that includes southwestern Georgia, northern Florida, Alabama, Mississippi, Louisiana, Arkansas, Texas, eastern Oklahoma, extreme southeastern Kansas, southwestern and eastern Illinois in the Mississippi Valley to Iowa and southwestern Kentucky. However, specimens may be difficult to locate in portions of their historic range as the construction of dams, commercial collecting, habitat loss and pollution have made a negative impact on many alligator snapping turtle populations.  In Texas the alligator snapping turtle is found in the Trinity River from Tarrant County and river systems eastward

BEHAVIOR AND ECOLOGY:  Alligator snapping turtles are aquatic bottom dwellers. They have been found in a variety of environs including lakes, oxbows, bayous, deep rivers, canals, creeks, ponds and even brackish estuaries. This species is an opportunistic feeder known to consume a wide variety of food items including but not limited to: acorns, briar roots, various aquatic plants, insects, crayfish, mollusks, fish, salamanders, frogs, turtles, snakes, opossums, nutria, and mink. Despite the varied diet, this turtle is best known for its ability to lure unsuspecting fish into its mouth. This is accomplished by holding the mouth agape and wriggling a brightly colored potion of the tongue in a manner similar to a convulsing and drowning worm. When the fish moves in for a closer inspection the mouth is slammed shut, water expelled through the nostrils and the fish is swallowed. Another feature possessed by this turtle is the re-curved cusp at the end of the beak. This characteristic is undoubtedly useful for securing struggling fish. Adults can stay submerged for intervals of 30 to 50 minutes. Occasionally, submerged specimens can be seen gulping water and expelling it through their nostrils. This behavior is suggestive of pharyngeal respiration which involves a gaseous exchange across capillary rich surfaces in the throat..

Females do not reach the behemoth proportions exemplified by old males.  Females are distinguishable from males by having a cloaca opening that does not extend beyond the posterior margins of the carapace. Females can lay as many as 50 eggs per clutch. Incubation temperatures ranging from 20-25 degrees centigrade have resulted in incubation times of 79 to 107 days (Ernst, et al., 1994). The average incubation period for eggs hatched under captive conditions is roughly 80 days. Upon hatching, alligator snapping turtles average 38 mm in carapace length.

ALLIGATOR SNAPPING TURTLE (Macrochelys temminickii), (HARLAN, 1835)
Museum voucher specimens are invaluable assets for making cool discoveries about the private lives of organisms. A CT scan of a hatchling alligator snapping turtle is provided in comparison to the shell of a baby that was little more than 2 years old when it was killed by a raccoon in 1998. Notice t
This specimen was approximately 2-3 years old when it died. Notice the amount of skeletal development on the carapace compared to the baby specimen in the CT scan image.
In April 2009 I received an email from Jeff Trevino regarding a large dead alligator snapper he found floating in Buffalo Bayou very close to down town Houston. The likely cause of death involved two large "J" style catfish hooks on weighted lines found in the throat.  No sign of trauma was found
In April 2009 I received an email from Jeff Trevino regarding a large dead alligator snapper he found floating in Buffalo Bayou very close to down town Houston. The likely cause of death involved two large "J" style catfish hooks on weighted lines found in the throat.
In April of 2010 I received this image of an adult specimen that had been shot in a neighborhood retention pond that connects to Little Cypress Creek in Cypress, Texas.  Asides from the tragic loss of the turtle the specimen was disposed of before it could be salvaged.
Harris County
Tarrant County
Leon County
Anderson County
The description of Macrochelys temminckii as published in: Troost, G. 1835. In: R. Harlan. Medical and Physica Researches or Original Memoires in Medicine, Surgery, Physiology, Geology, Zoology, and Comparative Anatomy. L.R. Bailey, Philadelphia. xxxix + 653 pp.