Terrapins are a species of freshwater reptiles that are similar to turtles, yet distinct. Unlike turtles, these reptiles spend most of their life in the water, and visit land specifically to lay eggs and bask in the sun. Take proper care of terrapins if you intend to house them as pets. Identify the gender of your terrapin if you want to breed it, or if you have several terrapins and wish to keep them apart so they do not breed. A terrapin has several identifying features that can help you distinguish the male from the female.
Measure the length of an adult terrapin's body. Male terrapins attain sexual maturity when they are 18 months old, while female terrapins are sexually mature at three years of age. Male terrapins grow to 18 cm (7 inches) long, while female terrapins can reach 30.5 cm (12 inches) in length.
Observe the body structure of the terrapin. Females have a bulkier body, unlike males, which are streamlined. The dome area of the shell or plastron in males is flat and concave, while in females it is high and convex.
Check the size of the terrapin's tail. Male terrapins have a long, wide tail that is three times the size of similar-sized female terrapins. Additionally, the cloacal opening in males is further away from the base of the tail compared to females.
It's harder to tell the sex of a baby terrapin, but one clue is the nails. Males have larger nails compared to females.