Pond Turtle, Emydidae
Emydidae is a family that contains nearly fifty species of pond turtles, also known as marsh turtles, which can primarily be found in the Western Hemisphere. This family is most closely related to tortoises and shares a few characteristics with them including similar iliums. Most species within this family have an arched carapace, or upper shell, although some have domed shaped shells, and many have one or two ridges on the top of the shell, which is known as a keel. It is common for the top and bottom shell to be connected with a large bridge. Each foot has some amount of webbing, giving the turtles great swimming abilities.
Pond turtles can be strictly herbivorous, carnivorous, or anything in between, so the diets of each species vary greatly. Carnivorous pond turtles consume fish, annelids, and crustaceans and it has been found that some carnivorous juveniles can turn into herbivores as they grow into adults, although it is not known why this occurs. The mating habits of many species have been extensively studied whole others of have not been studied at all. The breeding season of pond turtle occurs once per year, during which time males can be seen fanning the faces of females with their elongated fore claws. Egg clutches can hold over thirty eggs and females can breed many times throughout the mating season.
Natural threats to members of the Emydidae family include raccoons that raid their nests and alligators, which feed primarily on adults. Other threats include being sold in the pet trade and habitat loss. Many Asian species have been over collected and the Clemmys muhlenbergii species in America appears in Appendix II species by CITES as endangered or threatened. However, turtles also pose a threat to other habitats and species when they are carelessly released into the wild, like the pond slider, which has expanded its natural range due to this issue.
Image Caption: Black-Knobbed Sawback Hatchlings (Graptemys nigrinoda nigrinoda). Credit: M. Noth/Wikipedia (CC BY 1.0)