How to Determine a Snake's Sex

how to tell the sex of a snake

Illustration: © The Spruce, 2018

Sometimes snake owners want to know how to sex their snake. The problem is that it's not as simple to find out if a snake is male or female as it is in many other animals. On the outside, male and female snakes look similar. However, with a bit of experience, there are ways to differentiate between the two.

The following methods of sexing snakes should only be done by experienced caretakers or veterinary staff. If you are a beginner in snakes and want to know the sex of your snake, find an experienced reptile keeper or vet to demonstrate these methods to you. There is a risk of injury to the snake if they are done incorrectly.

Tail Characteristics

Male snakes have a pair of tube-shaped hemipenes (sex organs) that normally sit inside their bodies. They are basically two small penises that are kept safe inside the snake's tail. Female snakes do not have hemipenes.

The hemipenes are located just below the cloacal (vent) opening and down along the tail on either side of the snake's midline.

Since these sex organs are housed inside the male snake, they may not be obvious to you at first. There are visible clues that they are there, though. You can look at the shape and length of the tail to help you decipher whether or not your snake is a male. 

Males will have a tail (the portion of the snake starting after the cloacal opening) that is thicker and longer than their female counterparts. It also tapers differently: starting out thick and then suddenly thinning out to the tip. Female snakes have an overall thinner and shorter tail than a male and it tapers evenly to the tip.

While the differences can be fairly notable when comparing snakes side by side, it is more difficult to sex a snake if you don't have a male and a female to compare. This is why the following methods are more commonly used to accurately identify a snake's sex than looking at tail characteristics.

Probing

Probing a snake involves inserting a thin metal rod (called a snake probe) into the cloacal vent of the snake while it is awake. This special probe can be inserted further in males since they have a hemipenis on either side of the vent. The probe will drop down into one of these spaces that point towards the tip of the tail.

When probing a female snake, the probe will not drop down into the vent very far. That's because there is no space for it to go when you are directing the probe towards the tip of the tail. Females only have small scent gland spaces.

Picture two long socks inside the tail of a male snake that open up at the vent of the snake and you are basically visualizing the hemipenes. The lubricated probe will slide into the vent in the direction of the tail and into one of the hemipenes located on either side of the snake's tail if it is a male.

  • If it is a female, the probe will only drop in an average of one to three scales.
  • If it is a male, it will drop in an average of nine to fifteen scales.

On the probe's scale, the difference between the sexes is quite dramatic. With larger snakes, the probe is actually dropped into more of a pocket.

Probing a snake should only be done if you have someone to hold your snake still, have appropriately sized snake probes, and the confidence to do this carefully and correctly. You do not want to harm your snake. If you are unsure how to safely perform this procedure then you should not attempt it.

Popping Hemipenes

If you don't know what it means to "pop" a hemipenis, then the term may frighten you. Technically, it means temporarily reverting them so they are visible outside the tail (this is what happens when hemipenes prolapse).

To do this, pressure is firmly but gently applied with a finger on the snake below their vent where the hemipenis would come out. If it is done correctly, a hemipenis will pop out.

This method can typically only be done on smaller snakes like ball pythons, and it can cause a lot of trauma if done incorrectly. This is not the preferred manner of determining the sex of a snake since it is difficult to do. Also, you may not know if you were simply unable to pop the hemipenes or if the snake doesn't have hemipenes (is female), to begin with.