How to Tell the Sex of a Baby Turtle

Even people who don't ordinarily like reptiles often find themselves drawn to baby turtles. In the wild, you can watch baby sea turtles less than 2-inches long emerge from their submerged nests and paddle their way across the sand into the waves. Freshwater species such as red-eared sliders are often sold at pet stores when they reach four inches in size. Whether the turtle you're observing is heading towards the ocean or splashing in an aquarium, there are certain ways to determine gender.

Pet baby turtle in hand
How to Tell the Sex of a Baby Turtle
credit: Isabel Pavia/Moment/GettyImages

Pet store turtles

Since 1975, the FDA bans selling baby turtles less than 4-inches long. The law came into existence as a response to children putting small turtles in their mouths and contracting salmonella. As the largest of the pet store turtles, red-eared sliders are usually two or more years old by the time they reach four inches when they are legal to possess. Considering these turtles live to 20 years or more, they are still babies but are well on their way to developing telltale sexual traits. Turtles reach full maturity in five-to-eight years.

Those long fingernails

Although long fingernails are common on the female of the human species, in turtles, the opposite is true. The male turtle's front claws are longer and more curved than a female's of the same species. Although females dig in the sand to bury their eggs, males need their long claws to defend a territory and gain traction when mating with a female. Red-eared slider gender is easy to discern as this trait is very pronounced. In some species such as box turtles, the hind claws are thicker and more curved on the male.

Check the shell

In some species, it's easy to tell male from female turtles just by their body shape. Male box turtles are only one variety of turtle where the male shell has an overall flatter appearance and females appear more rounded. Feel the bottom of your turtle's shell. If it curves in slightly, it's a male. The concave shape helps him balance on the female turtle during mating. Females, on the other hand, have flat-bottomed shells. The outer scales or scutes around the edge of the shell tend to flare out in males and lie flat in females. Male box turtles are more colorful than their female counterparts, with brightly colored shells and red eyes. Both male and female red-eared sliders are colorful as babies but turn a muddy brown as they age.

A longer, thicker tail

Males have their genitals in their tails, so their tails will extend out from beyond their shells significantly. If just the tail tip shows when the turtle extends the tail, it is most likely female. Pick up your pet turtle and look underneath. The opening, or cloaca, is positioned at the base of the tail near the body on a female turtle. A male's opening is found further toward the tip of the tail.

Sea turtle gender

Baby sea turtles don't have x or y chromosomes that determine their gender. Instead, external conditions such as temperature play a primary factor as to whether they emerge from their egg as a male or female turtle. But it's not easy to tell a baby sea turtle's gender as they aren't sexually mature until around 10 years old. Even laparoscopic examination of some sea turtle species yields ambiguous results. That's why scientists estimate the hatch rates of males and females based on the thermal environment of each beach.

Recent experiments using a harmless biopsy from a turtle's gonad region could change the way scientists track the birth rates of species lacking sexual dimorphism. Known as immunohistochemical or IHC techniques, the samples are analyzed in the lab for subtle tissue differences between males and females of each species.