Instructions
Examine the Tail
Hold the turtle upside down carefully so the tail is fully visible.
Find the cloaca, which is the posterior opening in the turtle's tail. This opening is used to excrete feces and urine and for a female to lay eggs.
Examine the tail and cloaca. In a male, the cloaca is located farther down the tail than in a female, and a male's tail is typically longer and thicker. When the tail is fully extended, a male's cloaca is past the edge of the shell, known as the carapace. In a female, the cloaca is closer to the body, and a female typically has a smaller tail.
Study the Claws and Shell
Hold the red-eared turtle so that its front claws are fully visible.
Examine the turtle's front claws. A male's claws are much longer than a female's claws. These longer claws aid in the male's courtship and mating.
Hold the turtle so the underside of its shell, known as the plastron, is visible. As you examine the "belly," check to see if the plastron is concave or curves inward, which is another sign that the red-eared slider is a male.
How to Tell the Difference Between a Male and Female Slider Turtle
Like most turtles, red-eared sliders don't have obvious gender differences at birth. At their sexual maturity, however, the gender differences are more pronounced. A male is usually sexually mature at 2 to 5 years old, or when its shell is 4 inches in length. A female is sexually mature after 5 to 7 years or when its shell is 6 to 7 inches in length. Once your red-eared slider is an adult, you may use a few surefire ways to determine its sex.