Male vs Female Mystery Snail

Mystery Snail or Pomacea bridgesii
© MHawkinson/

Written by Jeremiah Wright

Updated: September 25, 2023

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The most frequent unclarity among mystery snail owners is their sex, so we’ve decided to help out with this.

You might’ve ended up on this page because you already have one or more mystery snails in your tank, or you’re planning to get some. But let us tell you a secret that makes this whole thing even more difficult: mystery snails can change their sex. That’s huge, right? It’s a strange fact, but it’s true. How? Why? When? We’ll clear this out, don’t worry!

First, we’ll tell you what a mystery snail is to make sure we’re on the same page. Then we’ll provide you with some tips on how to check its sex, and we’ll discuss the sex change process.

What is a mystery snail?

Mystery snail

A mystery snail is a species of apple snail.

©Arunee Rodloy/

A mystery snail is a species of apple snail. Apple snail is the common name for Ampullariidae, a family of large freshwater snails. Mystery snails are part of this family and have the binomial name Pomacea bridgesii. They are also called spike-topped apple snails. They usually grow as long as 1.5 inches and have 6-7 whorls. Apple snails and mystery snails implicitly have branchial respiration. This means that they have both gills and lungs, making it possible to breathe outside water. Mystery snails also have siphons that are extended above water so that the snail can breathe underwater. 

Some other exciting characteristics mystery snails have are the operculum and the structure of their eyes. The operculum is a kind of trap door that allows the snail to seal the entrance to the shell. It is mostly used when they hibernate in the mud during dry periods. 

A study mentions that mystery snails have “structurally complex eyes at the tip of a cephalic eyestalk.” Their mid-eyestalk helps regenerate the eye after amputation. New lenses and retinal differentiation appear 14 days after the amputation, and the eye is completely regenerated within 25 days after the amputation. 

Is my mystery snail male or female?

An interesting way that points to the sex of the mystery snail is the translucent shell.


Ok, so we’ve figured out what a mystery snail is. Now, let’s discuss their sex because that’s why we’re here. To be able to determine this, we have to consider a few aspects: their physical characteristics, their behavior, and the color of their shell.

Physical characteristics

The easiest way to check the snail’s gender is by turning it upside down. This way, you’ll be able to see if it’s a female or a male snail. Check the upper part of the right mantle cavity. If there’s a penis sheath next to the gills, then your snail is male. If you don’t see a penis sheath, it’s female. 

Another interesting way that points to the sex of your mystery snail is the translucent shell. If you notice that your snail’s shell becomes translucent, it means that the snail has entered breeding time. Now you can be sure that it’s a female snail. The thing is that you can’t check it when you bring it home, for example. You’ll only be able to use this method during breeding time.

Another way is to wait for the snail to grow bigger. You’ll be able to notice the aspects mentioned above more easily.


Observing the behavior of your snails can help you only if you have more of them. If you notice a snail climbing onto another one, it’s a male. The male snail does this to impregnate the female because mystery snails are not asexual. Their reproductive system requires both a male and a female snail. 

Once the male snail inserts its penis into the female genital aperture, it will remain this way for several hours. While the female will go on with her daily activities, the male will hide in its shell and wait for the fertilization to be completed. 

After this, the female will come above water and lay eggs. It’s usually done at night. Voila! Now you know which is male and which is female.

Shell color

This method is not scientifically proven, but many aquarists affirm that it’s accurate. In any case, you can check it for yourself and use the other methods mentioned above to strengthen your conclusion. 

The thing with the shell color is that it’s brighter in males. That’s it!

Why do mystery snails change their sex?

Mystery snails are not hermaphrodite species.


Mystery snails are not hermaphrodite species. This means that they do not have both male and female sex organs. Instead, they can change their sex when they feel the need to. This happens due to various circumstances. 

One thing that causes a mystery snail to change its sex is the environment. If they don’t feel comfortable as they are, they will change their sex. Other factors include their size or the water quality they live in. Even if a mystery snail changes its sex, it will still require a male or female counterpart for breeding.

How do mystery snails change their sex?

Mystery Snail or Pomacea bridgesii

Some mystery snails transition over a much longer period of time.


We know it sounds a bit strange that mystery snails can change their sex, but it’s possible. Let us tell you how this happens. 

The length of the process depends on your snail. Some mystery snails transition over a much longer period of time. This means you won’t be able to see the transition as it does not happen right away. During the transition, the testis becomes darker and smaller. If needed, the mystery snail can transition back to its original sex, which may take a few hours or a few days. 

Are female mystery snails bigger than males?

There’s no evidence that female mystery snails are bigger than male mystery snails. Both of them grow as much as 1.5 inches long. If you notice that your mystery snail is growing bigger, it’s highly unlikely your snail is specifically a mystery snail. It may be another species of apple snail – some of them grow as big as 6 inches.

Bonus: Will Mystery Snails Reproduce in My Aquarium?

Snail Eggs- Giant snail laying eggs

A close-up of what snail eggs look like. The female mystery snail will lay its eggs above the waterline of a freshwater tank.

©Alexandr Jitarev/

Yes, mystery snails can reproduce in a freshwater aquarium. You’ll need at least one male and one female. Once impregnated, the female would lay her eggs above the waterline, which takes 2-3 weeks to hatch.

As mystery snails grow large, it’s important to have a tank that’s large enough to accommodate them, thus avoiding overcrowding. The general rule of thumb is to have one mystery snail for every 2 ½ gallons of water. That translates into a maximum of four mystery snails in a 10-gallon tank. If you want mystery snail babies, you should invest in a 20-gallon aquarium, capable of housing up to eight of these lovely creatures successfully.

As females do lay a lot of eggs, you can wind up with many babies. The tank won’t sustain them so you’ll need to have a strategy for homing the new snails. Care for these snails is also intricate, so you’ll need to research the ins and outs of it before deciding to own a male and female mystery snail.

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About the Author

I hold seven years of professional experience in the content world, focusing on nature, and wildlife. Asides from writing, I enjoy surfing the internet and listening to music.

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