Discover the 11 Animals That Can Change Their Gender

Nature is truly fascinating, and some animals can change their gender, either for reproduction or if they are born as one gender and change into another as they mature. Animals that have both male and female reproductive organs are known as hermaphrodites, while other animals change their gender due to global changes, and others can switch their gender for reproductive purposes.

Now, it may seem strange and impossible to some people, but this phenomenon is happening in many different species of animals, from fish to birds, and even reptiles like bearded dragons and certain species of snakes.

Before we get into how animals can change their gender, we will explain how and why this happens.

How Do Animals Change Their Gender?

Animals can change their gender for four main reasons:

• Environmental response
• Gender reversal
• Born with both sex organs
• Reproductive advantage.

Animals can change their gender due to adaptations that allow their species to survive, as survival is key in the animal kingdom. Some animals need to change their gender or even go through a process that allows them to switch between male and female reproductive organs to survive and reproduce successfully as a species.

They don’t do this for fun, as gender-switching can be beneficial for the animal that allows their species to survive and adapt. In some cases, temperature also plays a role in the development of an animal’s gender, which can be seen in some species of snakes and fish. This happens when an egg develops at a certain temperature and will determine what gender the animal hatches as, meaning a male egg could turn into a female at a specific temperature.

Hermaphrodism happens when an animal has both male and female reproductive organs and can even be capable of self-fertilization. Animals that are hermaphrodites produce female and male cells (gametes) and it is seen in both invertebrates and vertebrates, such as fish and mollusks.

Other animals that can reverse their gender such as oysters do it usually because of certain hormones being suppressed. If a chemical or environmental change suppresses either their testosterone or estrogen production, the animal will have more of a certain hormone that influences their gender. This is common in areas where a synthetic hormone has leached in waterways where frogs are, usually from pollution and the gender change happens as a response to changes in their environment.

Fun Fact: Some female snakes can fertilize their own eggs through a process known as parthenogenesis or asexual reproduction.

Let’s get into the animals that can change their gender.

1. Clownfish

Clownfish are known as sequential hermaphrodites and are born with both male and female reproductive organs. The change is driven by hormones and the change happens in their brain first before it affects their actual reproductive organs.

All clownfish are born male, but they can change into a female if necessary. However, once the gender change is made, the clownfish cannot change back into a male. It is usually the biggest male in the group of clownfish that will make the transition into a female, as not all clownfish will change their gender.

The process happens when the testes start to dissolve, and the ovarian tissue increases. It can take over a month for this process to complete, and eventually, the clownfish will be a female. Clownfish will change their gender so that they can reproduce and not have to worry about searching for a mate.

2. Sea Bass

Sea bass is found throughout the United States, from Maine to Florida. These are medium-sized marine fish that live in the ocean, and they are native to the North Pacific Ocean.

The gender change in sea bass usually happens due to supply and demand. This is because female sea bass can change to male if they notice that there is a decrease in the male sea bass population. This makes the sea bass a protogynous hermaphrodite, which means the sea bass is born as one gender, but it can change into another at some point in their lives. Not all sea bass will change their gender, it will depend on whether it is necessary for the population.

3. Wrasse

Wrasses are a family of marine fish that can change their gender. Like the sea bass, wrasse are also protogynous hermaphrodites. This allows for a complex mating system where females or male wrasse can change into the opposite gender if necessary. If there is not enough of either a male or female wrasse in the population, the wrasse will undergo the change to change their gender.

This was tested by placing two male wrasses into one aquarium, and the smaller of the two-wrasse turned into a female. This is a great way for fish to continue their species’ survival without having to worry about there not being enough mating partners available.

4. Banana Slugs

The banana slug is a bright yellow gastropod native to areas of the Pacific Northwest. Unlike the other animals we mentioned above, the banana slug has both reproductive organs, and they are hermaphrodites.

In some cases, the banana slug can fertilize themselves, so they don’t always rely on each other for successful mating. However, they typically prefer to mate with each other and will fertilize themselves if there is no other option.

5. Grouper

Groupers are large fish from the bass family, commonly found in warm seas, making them marine fish. Groupers such as the yellowmouth grouper are monandric protogynous hermaphrodites, which means that they mature as females, but they can change to a male after sexual maturity.  

Some groupers are born male, and once they mature they can transition into females. Most groupers are females, especially if they are still young. The gender change can be based on a response to their age or size. Some will only change their gender when there are too few males around.

6. Northern Cardinals

Even though a gender change is very rare in birds in comparison to other animals such as fish, insects, and reptiles, it is possible. The northern cardinal is an example of a bird that has bilateral gynandromorphism. This is where the bird is born with both male and female feathers.

The female will usually have brownish-grey feathers, whereas the male has bright red feathers on the right side. These types of cardinals haven’t yet been observed to have a mate. There’s still a lot of research needed to be done on bilateral gynandromorphism in animals.  

7. Frogs

Frogs are found throughout the world, inhabiting freshwaters. This is a good example of an animal that can change its gender due to environmental changes. Relying on both the environment and their genetics to determine their gender, some male frogs can develop female reproductive organs due to hormone changes.

This is typically caused by pollution from humans. Synthetic hormone waste has polluted their environment and triggered a sex change in male frogs.

8. Green Sea Turtles

Green sea turtles can change their gender based on the temperature, usually when they are still developing in the egg. The incubation temperature can determine a green sea turtle’s gender. A warmer nest means that the hatchlings are more likely to be female.

Unfortunately, climate change and rising temperatures are affecting the increase in female turtles hatching, especially in Australia in Queensland’s north. Once a green sea turtle is born as either male or female, they cannot change their gender.

However, if the egg is a male, the temperature can influence the turtle to develop as a female.

9. Snails

Snails are hermaphrodites and have both male and female reproductive organs. They have the option of being able to switch from male to female when necessary.

Interestingly, some snails can self-fertilize. This means that they do not always need a partner to lay a fertile batch of eggs. Most snails still prefer to mate with another snail before laying fertile eggs. A female can store a male’s sperm for a long time.

So, if you have a pet snail and you have noticed they have laid eggs, it is usually because they have stored sperm from a previous mate with another snail, even months later.

10. Bearded Dragons

Bearded dragons can change their gender before development, depending on their chromosomes and the temperature in which they develop. When bearded dragon eggs are incubated at higher temperatures while they are still developing, it can turn the male bearded dragon egg (with male chromosomes) into a female.

The typical temperature that it happens around is about 89 degrees Fahrenheit (32 degrees Celsius). The bearded dragons will have the right chromosomes to turn into either a male or female. The environmental influence from the temperature can affect their gender when they hatch.

However, once a bearded dragon has developed in the egg, it cannot change its gender.

11. Butterflies

Beautiful and colorful, butterflies are flying insects that can be found throughout the world. These creatures can change their gender when the butterfly has a condition known as gynandromorphism. Although it is extremely rare, it is still possible, and they are sexually dimorphic species.

One-half of the butterflies wings are female, while the others are male. The butterfly with gynandromorphism will have both male and female characteristics when something happens to their chromosomes.

Conclusion

Animals are amazing creatures, and they have many cool and fascinating abilities that can benefit their species. From being able to change their gender for mating purposes, being born with both reproductive organs, or even showing male and female characteristics, some animals can change their gender entirely.

Summary of 11 Animals That Can Change Their Gender

Here’s a recap of the 11 animals we took a look at that are able to transform into another gender.

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