Black-knobbed map turtle
Black-knobbed map turtle | |
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Black-knobbed map turtle at Columbus Zoo and Aquarium | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Testudines |
Suborder: | Cryptodira |
Superfamily: | Testudinoidea |
Family: | Emydidae |
Genus: | Graptemys |
Species: | G. nigrinoda
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Binomial name | |
Graptemys nigrinoda Cagle, 1954
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Subspecies[3] | |
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Range map | |
Synonyms[4] | |
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The black-knobbed map turtle (Graptemys nigrinoda), formerly known as the black-knobbed sawback, is a small to medium-sized aquatic turtle with light gray skin.[5] Some of the most distinguishing characteristics of the black-knobbed map turtle, and the Graptemys genus, are the protruding "spikes" on the turtle's carapace. This species inhabits mainly the fall lines of rivers in the Mobile Bay drainage, in Alabama and Mississippi.[6]
Description
The
The carapace is dark olive-brown in color.
The head is small, and is dark brown with yellow stripes, with yellow crescents behind the eye facing towards the posterior end of the turtle. These stripes continue on the legs of the turtle also, with the underside of the leg being lighter than the
Sexual dimorphism is evident in this species. Females are roughly twice the size of males. Also, females' carapaces tend to be higher than those of males, though the males have longer tails than the females.[7] Sizes (carapace lengths) have been recorded as ranging from 7.6 to 10.2 cm (3.0 to 4.0 in) in males and 10.2–19.1 cm (4.0–7.5 in) in females.
Distribution
The black-knobbed map turtle is endemic to the southeastern United States.[5] In Alabama, they are found in the Mobile Bay drainage. In Mississippi, they are found in the Tombigbee River system and in the Black Warrior River as far north as Jefferson County, Alabama.[5] They are only able to survive in fresh water, thus they are only found within freshwater river systems.[5]
Habitat and ecology
Black-knobbed map turtles are seasonally active from April to late November.
When approached, the turtles jump into the nearby water. Once in the water, they seek protection between the branches of fallen trees on the river bottom.[10] Most of the riverbeds where they live have sand and clay bottoms with moderate currents.[6] Hatchlings prefer more sluggish waters off the main channel.[5]
Little is known about
Males reach
Conservation
Currently, this species has been petitioned and is under consideration for listing by the
Most of the lands encompassed by the species habitat are protected lands, but the rivers remain vulnerable. Mobile River Basin Aquatic Ecosystem Recovery Plan
Captive breeding has been an option for conservation efforts as well. Captive breeding is plausible for increasing population sizes in captivity.[9] However, it remains unclear if captive-bred black-knobbed map turtles can be released into the wild and breed on their own. Black-knobbed map turtles are popular in the pet trade, but became more common because of captive breeding.
References
- . Retrieved 22 May 2023.
- ^ a b "Graptemys nigrinoda". NatureServe Explorer An online encyclopedia of life. 7.1. NatureServe. Retrieved 9 December 2023.
- ^ Graptemys nigrinoda, Reptile Database
- .
- ^ a b c d e f g h Blankenship, Emmett L., Brian P. Butterfield, and James C. Goodwin. 2008. "Grapemys nigrinoda Cagle 1954 - Black-Knobbed Map Turtle, Black-Knobbed Sawback." Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs (ISSN 1088-7105) (5): 005.1 - 005.6.
- ^ ISBN 0-394-50824-6. ("Black-knobbed Sawback", Graptemys nigrinoda, pp. 462-63 + Plate 281.)
- ^ a b c d e f g h Lahanas, P.N. 1982. Aspects of the life history of the southern black-knobbed sawback, Graptemys nigrinoda delticola Folkerts and Mount. Master’s Thesis, Auburn University, Auburn, Alabama. 243 pp.
- ^ Mount, R.H. 1975. The Reptiles and Amphibians of Alabama. Auburn Univ. Agr. Exp. Sta. Auburn, Alabama, 347 pp.
- ^ a b c d Waters, J.C. 1974. The biological significance of the basking habit in the black-knobbed sawback, Graptemys nigrinoda Cagle. Master’s Thesis, Auburn University, Auburn, Alabama.
- ^ "Black-knobbed Map Turtle." Graptemys.com Map Turtles. N.p., n.d. Web. 6 Apr. 2011. <"Black-knobbed Map Turtle". Archived from the original on 8 October 2011. Retrieved 28 April 2011.>
- ^ U.S. Fish and Wildlife Service. 2000. The Mobile River Basin Aquatic Ecosystem Recovery Plan. Atlanta, GA, 128 pp.
Further reading
- Cagle, F.R. 1954. Two New Species of the Genus Graptemys. Tulane Studies in Zoology 1 (11): 165–186.
- ISBN 0-395-19977-8(paperback). (Graptemys nigrinoda, p. 59 + Plate 8 + Map 17.)
- ISBN 0-307-13666-3(paperback). (Graptemys nigrinoda, pp. 52–53.)