Facts about the animal kingdom

How to Tell if a Turtle Is Male or Female

Ana Diaz Maqueda
By Ana Diaz Maqueda, Biologist specialized in ethology. July 5, 2023
How to Tell if a Turtle Is Male or Female

Sexing turtles requires looking for the reptile's sex organs, although there are other indicators. This is not an easy task and it is relatively common for pet owners to not know whether their turtle is male or female for a long time after adoption. Part of what makes determining the sex of a turtle so difficult is their carapace. Turtles have a hard shell which protects their soft tissues from predators and other dangers. They are able to bring their entire body inside the shell, including legs, head and tail. If they can bring their extremities into a shell, it should be no surprise they also hide their sex organs.

At AnimalWised, we find out how to tell if a turtle is male or female. If you have rescued a turtle, have a turtle as a pet or simply want to know more about these fascinating reptiles, we explain the best ways to sex a turtle.

You may also be interested in: How to Tell If a Chick is Male or Female


  1. How to tell if a turtle is male or female
  2. Body size
  3. Plastron concavity
  4. Carapace size and shape
  5. Tail size
  6. Anal notch
  7. PCR analysis

How to tell if a turtle is male or female

Determining the sex of a turtle can be a complicated task. As explained in the introduction, this is largely due to the fact their sex organs or not usually exposed. For a turtle, being male or female is genetically determined. However, depending on the temperature at which the embryos develop, there will be a greater abundance of females or males.

To know what we should look for when sexing a turtle, the first thing we must know is the species to which they belong. Each species of turtle has different characteristics when it comes to their sex. For this reason, determining the type of turtle species will make turtle sexing much easier. Once we do so, we can observe certain parts of the body such as the shell, the tail, the anal notch or the plastron.

To tell if a turtle is male or female, we need to look at the following factors:

Body size

Like other groups of reptiles, such as lizards and snakes, turtles exhibit sexual dimorphism. Sexual dimorphism in animals is the condition of different sexes of the same species having marked visual differences. A common example is the peafowl, where male peacocks have bright colors and a dramatic tail, whereas the female peahen is much more visually subdued.

The level of sexual dimorphism in turtles differs according to species with some having very marked differences and others looking similar. We can see starker sexual dimorphism in relation to size. This is seen certain turtle species such as yellow-bellied slider (Trachemys scripta scripta) and the Spanish pond turtle (Mauremys leprosa) in which the females are noticeably larger.

Males tend to be larger when we talk about species belonging to the Testudinidae family such as the Hermann's tortoise (Testudo hermanni) or to the Kinosternidae family such as the razor-backed musk turtle (Sternotherus carinatus), a common tortoise in the United States where it is more popular as a pet than the red-eared slider (Trachemys scripta elegans).

When the females are larger than the males, this difference in size is between 50 and 60 percent. While in species where the males are larger, the difference does not usually exceed 20 or 30 percent.

Despite size being a good indicator to tell if a turtle is male or female, it does not always help. If you only have one turtle, then you will not be able to compare them with another. We can measure the turtle, but won't be helpful until we know the stage of development of the reptile.

Learn more about turtle development with our article on how long do turtles live?

Plastron concavity

The plastron of a turtle is the underside. It is a separate piece from the shell, but the two pieces are fused together in a bridge. It is the ventral part of the turtle and sometimes referred to as its belly. The degree of concavity of their plastron can help us determine whether the turtle is male or female.

The concavity needs to be measured at the back of the plastron. The space we need to look at is roughly between the hind legs. In this gap, the concavity is more pronounced in females. However, even this is not a great way to tell the sex of turtles. The difference between male and female may only be as little as 1 mm. Even experienced turtle guardians can find it difficult to distinguish them.

How to Tell if a Turtle Is Male or Female - Plastron concavity

Carapace size and shape

Many species of European tortoises tend to have differences in the shell depending on whether they are male or female. Generally speaking, the shell of the males is wider and with a triangular finish. This affords the male greater stability while copulating. In addition, the plastron has two bumps that are more marked in males than in females, giving the tail more freedom of movement.

Tail size

In most turtle species, the tail is usually longer in males. It also tends to be wider at its base, since the penis must be housed inside. On the other hand, the cloaca (reptile organ through which there is access to the excretory and reproductive systems) is closer to the tip of the tail in males and closer to the base in females.

Anal notch

The anal notch can be seen when looking at the turtle's plastron. It is the distance that exists between the end of the plastron and the end of the carapace. In males, this anal notch is usually larger than in females for many species of tortoises, as they must have greater freedom of movement for the tail. This is important for the penis to reach the female's sexual organ.

Learn more about this process with our guide to turtle reproduction.

How to Tell if a Turtle Is Male or Female - Anal notch

PCR analysis

The most effective way to determine the sex of a turtle is through an analysis of its DNA using PCR (laboratory analytical technique). A veterinarian can draw blood from the animal, send it to a laboratory, and in a few days the sex of the turtle will be known for sure.

To carry out this genetic testing of a turtle to determine whether it is male or female, you will need to speak to your veterinarian. Not all veterinary clinics will have the facilities to do this testing, but they will be able to know where is the nearest place it can be carried out.

If you want to read similar articles to How to Tell if a Turtle Is Male or Female, we recommend you visit our Facts about the animal kingdom category.

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How to Tell if a Turtle Is Male or Female