Instructions
Find out which species of turtle you have (see Resources). You have to know the species before you can tell if a turtle is a female or male because sex characteristics are not the same for all species. A good guide will also help you determine if the turtle is full grown so you can tell the sexes apart.
Look for sex differences that are specific to the species of turtle. In some cases a sex-linked feature will indicate one sex in some turtle species, but the opposite sex in another kind of turtle. For instance, female spotted turtles have red eyes while the males have brown eyes. Among box turtles, it’s the male who has the red eyes and the female who is brown-eyed.
Observe the turtle’s behavior and general chrematistics. Although females are larger on average they have smaller claws. A male turtle is more aggressive, particularly during the mating season.
Check the turtle’s underside. The plastron (or lower shell) will be curved inward (convex) for most male turtles. Female turtles usually have a flat plastron.
Examine the cloaca and tail of the turtle. Unlike mammals, a turtle has only a single opening at the rear to excrete waste and lay eggs. This opening, called the cloaca, is located under the tail of the turtle and is closer to the body in female turtles. A female turtle’s tail is also shorter and narrower than a male’s.
How to Tell if a Turtle is a Female or Male
At first glance, one turtle looks pretty much like the next. However, the turtles themselves can tell if a turtle is female or male and you can learn to do it, too. You won’t be able to tell the difference until a turtle is full grown (about 3 to 5 years) when sex characteristics have emerged. To do that requires the expertise of a biologist and the use of special tests. For mature turtles, though, the steps here will enable you to tell if a turtle is female or male.