Sexing Water Turtles
It is important to know the sex of your turtles. Mature females MUST have land access to dig and lay eggs in even if they have never been around a male. They can still lay unfertile eggs. If a mature female does not have land access, they can become egg-bound and this can lead to infection and death.
Many male water turtles have very long front toenails and will stick their front legs forward toward another turtles face and flutter their nails during courtship. The one receiving the flutter could be either sex. A female will never exhibit this fluttering behavior, but young males will flutter before females AND other males.
Male water turtles will also have longer thicker tails than the females. The cloaca (vent) will be closer to the body on a female and the male's cloaca will be farther from the body usually beyond the edge of the carapace (upper shell).
To see some photos please see this link: Sexing Water Turtles These photos would also be good for sexing cooters and red-eared sliders.