Clownfish: The Girlbosses of the Waters

Finding Nemo is a heartwarming movie about a young clownfish trying to reunite with his dad– or, should I say, his mom. You may know that in the movie, Nemo’s father, Marlin, is forced to assume the role of a caretaker after his wife dies. Females stereotypically take on this role, but males can do it as well. As a matter of fact, when the need arises, male clownfish take this adaptation to the next level.

Clownfish lay hundreds of eggs, yet none hatch into females. Rather, male clownfish transition into females around 12 to 24 months after birth. But how exactly does a Marlin turn into a Marlene?

The process starts in the brain’s preoptic area (POA), which is responsible for gonad function, or the reproductive organs. The POA of a female clownfish has around twice the number of cells than the POA of a male, so the male clownfish first starts to grow in this area until it is fully female.

After this, the gonad of the clownfish starts to change. Clownfish are hermaphroditic animals, meaning that they have both male and female organs. Their gonads are called ovotestis, which contain both testicular and ovarian tissue. In males, the testicular tissue matures into testes, while the ovarian tissue remains immature.

When a male transitions into a female, its testes start to disintegrate, while its ovarian tissue starts to grow. After a while, the testicular tissue is resorbed, and the female matures, completing the transition.

The female then proceeds to be a girlboss, slaying its enemies, defending the nest, and protecting its young. Meanwhile, the next largest male fish becomes its mate and takes on the role of looking after their eggs. The rest of the fish in the group simply wait and hope for a chance to move up the social ladder, which will occur in the event that the female dies or disappears. In that case, its mate would transition into a female, and the largest of the remaining fish would become its mate.

This then brings to mind the question of why the smaller clownfish would choose to remain in the group instead of searching for other groups wherein they can reproduce. The answer is simple–it is the best way to stay alive.

Being part of a group, no matter how low on the social ladder, has its benefits. Clownfish are also known as clown anemonefish because of their symbiotic relationship with sea anemones. These animals have stinging tentacles as a means of protecting and feeding themselves. Clownfish have a protective layer of mucus on their skin, which prevents them from being harmed by anemones. They are thus able to live within the tentacles of anemones, protecting them from predators in exchange for nourishment in the form of food scraps.

Not only is staying in a group beneficial to clownfish, but leaving the group actually poses several risks. If they stray from the protection of the anemone, they may just end up like Nemo’s mom – fish food. Because of their small size, clownfish attract many predators eager to make them a snack. It goes to show that staying in a group, even if it means that they do not reproduce, is the more logical and safe option.

In the depths where clownfish roam, remarkable discoveries unfold. From complex transformations to intricate social hierarchies, these fish prove that life beneath the sea is anything but clowning around. So, the next time you watch Finding Nemo, remember that there's more to these fish than just a tale of lost fins and daring rescues. Their lives are a saga of survival, adaptation, and the eternal quest for a safe anemone to call home.

Sources:

https://pubmed.ncbi.nlm.nih.gov/36509136/

https://www.britannica.com/science/hermaphroditism

https://www.nature.com/articles/srep35461

https://www.bu.edu/articles/2024/clownfish-studying-their-complex-lives-and-anemone-homes/