Gender is not always binary. Nature does not make gender a choice between one and the other. In truth, many creatures in animal land flit between male and female, changing gender based on their environment, availability of mates, and various biological desires. Still, others show characteristics of both male and female organisms within their species.
Here are eleven animals that can change their sex!
Parrot Fish
Parrot fish always hang out in groups. These groups (since they are fish, they are called “colleges”) are always led by a dominant male, who is looked up to by several female parrot fish. But, these female parrot fish are not what they seem. They are considered “secondary adult males.” This means they display all the traits of female fish (such as being reproductive machines), but if the dominant male of the animal group dies or is unable to perform his role as leader, such a “secondary adult male” will change his sex and become the number one male! This is called different kinds of animal.
Clownfish
They are bright orange, they are cute, and they are known for “Finding Nemo” and “Finding Dory.” Aside from parrotfish, clownfish can change their sex if the leader of their animal group is no longer able to fulfil his duties. Animal Groups of clownfish consist of one large male and one very large female. The rest of the fish in the group are smaller, immature males. If the female dies, the larger male becomes a female, and the most important “immature male” will become the mature male of the group of fish. This means a single clownfish can change its sex twice in its lifetime.
Banana Slug
It is bright yellow. It is taller than ten inches long. Of course, it’s named Banana Slug! These worm-like molluscs are what’s called “simultaneous hermaphrodites,” meaning that unlike clownfish (which are sequential hermaphrodites), they show both male and female tendencies (and show male and female organs) at the same time.
Although they may be capable of self-fertilization, most banana slugs usually mate with one partner. Once they mate, they produce both sperm and eggs. At the end of their mating, they have fertilized eggs that they usually deposit on the underside of leaves or logs. One mating method – double the number of offspring!
Hawkfish
These brightly coloured fish live in exceptionally large animal groups. And, like clownfish and parrotfish, they can change their sex according to the occasion. However, in parrotfish and clownfish schools this is usually because the male or female leader of the animal group dies, about hawkfish, sex change occurs when the group becomes too large.
Hawkfish animal groups consist of one male and several females. If a male has too many females in his group, the largest will become male, and the unmarried animal group of hawkfish will split into equal, but smaller groups of hawkfish.
Also, male hawkfish can become female again if a larger male outcompetes them or if the female population decreases and more females are needed to survive.
Moray eel
Moray eels are sequential hermaphrodites, just like clownfish. And, as with clownfish, only adult males become females. But, unlike clownfish, all moray eels make their life transition in a completely colourful and spectacular way. After the transformation, the moray eel lives out the rest of its life as an egg-laying female eel.
Unlike the common moray eel, the zebra and dragon moray eels change from female to male instead of from male to female.
Butterflies
Unlike all the previous animals on the list (except the moray eel), many butterflies enjoy and display hermaphroditism. Some butterflies display both male and female colours on their bodies and wings. This unusual circumstance is called gynandromorphism, and it can be caused by genetic errors during the early stages of the butterfly’s formation. Gynandromorphism can be seen in many animals, however, it is most spectacular and most amazing when you can see it on the butterfly’s wings.
African Clawed Frog
Scientists and researchers have begun observing spontaneous sex changes within frogs in their laboratories. Recently, they have observed the same thing happening in the wild. However, in both cases, it did not seem to be a natural way to happen. A large number of male frogs are becoming females, thereby developing useful reproductive organs. The reason for this turned out to be a common and well-known weed-killing chemical – Atrazine.
This chemical has now been banned in Europe. While it will get absorbed into the soil and then later carried into the rivers, it will reduce the hormone levels inside the bodies of those frogs. By suppressing testosterone Aron and the estrogen-boosting chemical managed to turn a lot of frogs from male to female.
Cardinals
Apart from having a very spectacular call, cardinals can also display bilateral gynandromorphism. According to an observation from Western Illinois College, cardinals not only display gynandromorphism, but they also start behaving differently. The study (conducted in 2008-2010) shows that gynandromorph cardinals did not participate in mating rituals with other specimens of their species. However, they were getting along perfectly regularly with other cardinals who showed no gender-nonconforming tendencies.
Cuttlefish
A species with similar elegance to squid and octopus, cuttlefish do not change their sex, although they can alter their colour and camouflage to appear as the other sex. This is usually done during dating rituals (before mating) to avoid excessive contention from other males in the area. But the cleverness doesn’t stop there! The cuttlefish changes its colour the way a gynandromorph might – one side suggests female colouration, while the other side suggests male colouration. A very clever trick! Very challenging though. This cannot be the basis for healthy cuttlefish dating.
Snakes
Copperheads, cottonmouths, and other female snakes are capable of giving birth to virgin babies. Called parthenogenesis, this means that females can fertilize their eggs if they don’t find a suitable male partner during mating season. Although this isn’t (technically) classified as sex exchange, it advocates that some female snakes can perform the reproductive activities of both males and females without being bisexual.
Green sea turtles
The eggs of green sea turtles are temperature-sensitive. The warmer the sand the eggs are buried in, the more female turtles are born from those eggs. For example, on the sandy beaches of Australia (where the ozone layer is thinner and temperatures are dramatically better), up to 99.8 of all green sea turtles hatched are female! Whereas the same species that lay eggs in cooler climates show a female-to-male ratio of births of 65/25. This can hurt the international population of green sea turtles, potentially leading to species decline and extinction.