The eastern river cooter (''Pseudemys concinna concinna'') is a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

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 ...

native to the eastern United States, with a smaller population in the midwest. It is found in freshwater habitats such as rivers, lakes, and ponds.

Taxonomy

The eastern river cooter is a subspecies within the

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 ...

Pseudemys concinna The river cooter (''Pseudemys concinna'') is a species of freshwater turtle in the family Emydidae. The species is native to the central and eastern United States, but has been introduced into parts of California, Washington, and British Columbia ...

'', known as the river cooter. The exact number of subspecies is debated, but most experts recognize two: ''P. c. concinna'', and '' P. c. suwanniensis''. Sometimes another subspecies, '' P. c. floridana'' is recognized, but this is often treated as a separate species.

Description

Eastern river cooters are capable of growing up to . The

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 ...

(upper shell) is typically dark greenish brown usually with a "C" marking facing the posterior. In western populations, the "C" may be reduced and many yellow markings may be present on each scute. The background color is reddish brown, unlike the other subspecies, ''P. c. suwanniensis'', which is very dark. The plastron (bottom shell) is yellow to reddish orange with a dark pattern between scutes that follows the scute seams (this fades with age). This distinguishes it from '' P. floridana'', which lacks the dark marks. The stripe down the hind foot is also a major characteristic, and ''P. suwanniensis'' can be distinguished by its lack of color on the legs. Females tend to grow larger than males, and have a smaller tail and more convex plastron. One particular distinctive feature of the eastern river cooter is that they have the ability to breathe underwater through a sac called the

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

bursae which is based in their tail. This allows them to stay underwater for extended periods of time, and makes their behavior harder to study.

Habitat and ecology

Eastern river cooters prefer areas with flowing water, such as rivers, but will also live in other freshwater habitats. They live in shallow areas with aquatic vegetation, and when in larger numbers, they live in deeper, clear water. In the wild they feed almost exclusively on aquatic macrophytes and

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

. Aquatic plants seem to make up almost 95% of their diets. Younger ones tend to seek a more protein enriched diet such as aquatic invertebrates,

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

, and

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

. Older turtles may occasionally seek prey as well, but mostly partake of a herbivorous diet. These turtles can sometimes be found basking in the sun, but are very wary and will quickly retreat into the water if approached. Otherwise, they are difficult to find in the water, which may be due to their ability to breathe while fully submerged. As a result, they are not often seen. In warmer climates, they are active year-round, but are not very active during winter in colder areas.

Reproduction

Eastern river cooter mating habits are very similar to the red-eared slider. As with the other basking turtles, the males tend to be smaller than females. The male uses his long claws to flutter at the face of the much larger female. Often, the female ignores him. If the female is receptive, she will sink to the bottom of the river and allow the male to mount for mating. If they do mate, after several weeks the female crawls upon land to seek a nesting site. They often cross highways looking for suitable nesting spots. Females will lay between 12 and 20 eggs at a time, close to water. The eggs hatch within 45 to 56 days and the hatchlings will usually stay with the nest through their first winter. Mating takes place in early spring. Nesting usually occurs from May to June. The female chooses a site with sandy or loamy soil, within of the river's edge. She looks for a rather open area, with no major obstacles for the future hatchings to negotiate on their way to the river. The nest is dug with the hind feet. She lays 10–25 or more eggs in one or more clutches. Eggs are ellipsoidal, approximately long. Incubation time is determined by temperature, but averages 90–100 days. Hatchlings generally emerge in August or September. There have been reported instances of late clutches over-wintering and hatching in the spring. A hatchling will have a round carapace, about diameter, that is green with bright yellow markings.

References

{{Taxonbar, from=Q3729395 Pseudemys Reptiles of the United States