The flattened musk turtle (''Sternotherus depressus'') is a critically endangered

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of freshwater

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Kinosternidae. The species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the southern

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Geographic range

''S. depressus'' is an endemic with a restricted range, historically inhabiting the Black Warrior River drainage of north central

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

. Conant, Roger (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. Houghton Mifflin. Boston. xviii + 429 pp. + Plates1-48. (hardcover), (paperback). (''Sternotherus depressus'', pp. 42–43 + Plate 4 + Map 9). Serious declines have been observed throughout its range, and it has likely been extirpated from greater than 70% of its historic range, especially in much of the Mulberry Fork and the Locust Fork of the upper Black Warrior River Basin. Sipsey Fork populations have fared significantly better due to protection offered by the

Bankhead National Forest The William B. Bankhead National Forest is one of Alabama's four National Forests, covering . It is home to Alabama's only National Wild and Scenic River, the Sipsey Fork. It is located in northwestern Alabama, around the town of Double Sprin ...

Description

A little turtle, ''S. depressus'' can have a straight

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

length of as an adult, with a record length of . Both the

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

and

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refer to the fact that the species' carapace (upper shell) is much lower and flatter than those of the other members of the genus ''Sternotherus''. In fact the flattened musk turtle looks as if someone had accidentally stepped on it, hence the common name.

Captivity

Individuals of ''S. depressus'' have survived for more than 20 years in captivity. Although reproductive rates are low for the species, ''S. depressus'' has been bred infrequently in captivity with relative success. Future propagation efforts may be key to preserving and reintroducing the species once its habitat has been restored.

Threats and causes of decline

Erosion and siltation from extensive strip mining for coal and damming have been the leading causes of decline in the flattened musk turtle, with clear cutting, development, and pollution also playing significant roles in habitat degradation throughout its historic range. As historically rock and bedrock bottom creeks have turned to mud and sand bottom creeks due to erosion, ''S. depressus'' has lost the rock crevices it relies on to escape predation and the high stream flow rates that characterize the streams it inhabits.

References

External links