Crayfish Sexing: How to Determine the Gender of Your Crayfish

To tell you frankly, I spent hours trying to figure out how to identify crayfish gender. Most of the resources are very complicated and for animal experts. It is quite hard for us, crayfish keepers to understand those scientific resources.

So, in this article, I’ll show you the differences in laymen terms so that even a beginner crayfish keeper can identify the crayfish gender.

How To Tell If A Crayfish Is Male Or Female?

Male Crayfish	Female Crayfish
Male crayfish is larger in size when sexually matured	Not as large as the male
The claw is larger in male crayfish	The claw remains comparatively shorter in female crayfishes
Male crayfish has a narrow abdomen	Female crayfishes tend to have a wider abdomen for storing eggs
Strong and fully developed Gonopod	Gonopod is not as developed as the males
The fourth set of pereopods (walking legs) has a nodule at the base. These are called Claspers.	No nodule at the base of the fourth set of pereopods. The third set of pereopods will have two holes at each side of the pereopod’s base. Eggs come out from these holes.
The pleopods (swimmerets) are less developed in the male crayfish.	The pleopods (swimmerets) are well-developed in the female crayfish.

I know seeing only the table above can make you more confused. I know it will make me. So, let me explain all these differences as easily as possible in the rest of the article.

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A Little Bit Of Crayfish Anatomy

Before we can identify the crayfish gender properly, we need to know a little bit about the crayfish anatomy. Please fear not, it will not be a biology class. I’ll just introduce you to the organs that are needed for differentiating male and female crayfishes.

*The image is taken as a screen shot from Kim Owen’s Crayfish Anatomy Video [very good resource for understanding crayfish anatomy]*

First, look at the claws. These claws are known as Cheliped or 1st walking leg set.

After the Claw, there are additional 4 pairs of walking legs. These walking legs are called Pereopods.

After the walking legs, on the abdomen of the crayfish, you’ll see very small sized legs like walking legs. These are called swimmerets of Pleopods. The first set of Pleopods is called Gonopod.

That’s all the anatomy you need to know for identifying crayfish gender. It was easy, right?

Determining Crayfish Gender: Infographic

how to determine crayfish gender infographic

Want to get a printable version of this infographic? Click here! [If you want to use this infographic on your website, please link back to this post as the source!]

Male vs Female Crayfish: 4 Differences

Before we dive into each of the differences, please know that adult crayfishes are much easier to sex than the juvenile ones. The juvenile crayfishes don’t have properly developed organs yet, so it can be much trickier to sex them.

All the images illustrated below are taken from Quizlet.com

1. Inspect The Gonopod

I think, inspecting the Gonopod is by far the easiest way to identify crayfish gender. In males, the Gonopod is very developed and large. In the females, you’ll be barely able to see the Gonopod.

In the above image, the gonopod is marked inside the red circle. You can’t see such a developed gonopod in the female.

2. Male Crayfish Have Claspers, Females Have Holes

It is very hard to see the claspers and holes in an image. You can definitely see these in real life by holding a crayfish closely.

In the male crayfish, the fourth set of pereopods (walking legs) has a nodule at the base. These are called Claspers. The females don’t have these claspers.

In the female crayfishes, the third set of pereopods will have two holes at each side of the pereopod’s base. Eggs come out from these holes. These holes are absent in the males.

3. Male Crayfish Are Larger

When sexually matured, males are typically larger than the females. The above image will give you a good idea about the size difference between male and female crayfish.

4. Claws Are More Prominent In Male Crayfish

As you can see, the claws are larger and more prominent in the male crayfish.

Do Crayfish Have Claws?

When you hear the name crayfish, the first thing that may come to your mind is an aquatic crustacean with claws. So, the answer is yes! Claws are significant parts of crayfish.

Crayfish use their large claws to defend themselves from the attack of predators. Hence, crayfish may grab your fingers whenever you try to hold them. These crustaceans make good use of claws by pinching or jabbing their enemies for protection.

Besides defending against predators, crayfish use their claws to threaten their competitors. Besides, these crustaceans use these claws to tear apart their enemies and food.

If crayfish need to dig up anything, these crustaceans will use their claws for this purpose. Not to mention, crayfish catch their food with their strong claws. However, the claws are larger and more prominent in male crayfish.

Frequently Asked Questions

What are the differences between Crawdad vs Crawfish?

“Crawdad” and “crawfish” are two different terms for the same freshwater crustacean, also known as a crayfish. The term used may depend on the region where one lives.

For example, people from the southern US commonly use “crawfish,” while people from the West Coast, Arkansas, Oklahoma, and Kansas often use “crawdad”.

The differences in the names are more geographical than anything else.

How to tell if a crayfish is a boy or a girl with their claws?

Determining the sex of a crayfish based solely on their claws can be challenging as it may not provide a definitive answer. However, there are certain characteristics that can provide some clues:

1. Size and Shape: In general, male crayfish tend to have larger and more elongated claws compared to females. Males often have one claw that is significantly larger than the other, known as the “crusher claw,” which they use for defense and mating.

2. Thickness of Claw Base: Males often have a thicker base where the claw attaches to the body, while females typically have a more slender base.

3. Claws’ Tips: In some species, the tips of the claws may have different shapes. Male crayfish may have more pointed or curved tips on their claws, while female crayfish may have flatter or broader tips.

What is the difference between male and female crayfish swimmerets?

Male and female crayfish swimmerets, also known as pleopods, can differ in size and function.

Male crayfish have a modified pair of swimmerets called gonopods that are used to transfer sperm to the female during mating. These gonopods are usually larger and more rigid than the other swimmerets.

In contrast, female crayfish have smaller swimmerets that are used for carrying eggs and for swimming. Female crayfish can have up to 8-10 pairs of swimmerets, while males usually have fewer.

How big is a female crayfish?

The size of a female crayfish can vary depending on the species. However, according to my sources, in most crayfish species, adult females are on average smaller than males.

The age of the crayfish is also related to its length, but there is considerable overlap between male and female size for many species.

On average, crayfish grow to 17.5 cm (6.9 in) in length.

Are male or female crayfish bigger?

Male and female crayfish can differ in size depending on the species. In most crayfish species, adult males are on average larger than females.

However, there is considerable overlap between male and female size for many species, and age is related to their length. Therefore, size alone may not be an accurate indicator of gender.

Can you keep male and female crayfish together?

It is possible to keep male and female crayfish together in the same tank. However, there is a risk of aggression and fighting, especially during mating and breeding. If the crayfish are not compatible or if there is not enough space or hiding places in the tank, they may attack and injure each other.

For a detailed answer, read my guide on keeping 2 crayfishes together.

Final Words

So, I hope all these graphical illustrations will help you out to differentiate between male vs female crayfish. I know it can be hard at the first time. However, after couple of practices, you can easily identify the gender of your crayfish.