What should have happened in Finding Nemo
Disney's film, Finding Nemo, is a story about a clownfish dad who is on a search for his lost son, Nemo who was taken away from the oceans by divers to live in a fish tank. Without clownfish to keep biodiversity in the oceans, other marine life would be ruined. Disney got that part correct; a variety of species and keeping fish in the ocean is necessary for everyone’s survival. However, there is one huge flaw in this movie. What is it, you may ask? Simply, Nemo's father, Marlin, should be his mother.
Clownfish are protandrous sequential hermaphrodites, meaning they have genes for both male and female hormones; however, the male hormone proteins are the first to express themselves. Since clownfish are born with immature male and female reproductive organs, they can convert from male to female later on when they need to. In a group of clownfish, there is a dominant female--the largest fish in the family--as well as the dominant male--the second largest fish. There can also be smaller neutral fish in the line for succession. Once the dominant female dies, the dominant male will step up and turn into the next dominant female, while the next largest neutral clownfish will turn into the dominant male. This allows for a new breeding pair, creating variation in the offspring without having to swim the dangerous waters searching for a new mate. So how does this happen?
As the fish transitions, different cells, tissues, and organs are put into play. The change first starts in the brain. Neurons-- cells that pass information to other cells, tissues, glands, and organs begin appearing or disappearing in certain areas of the brain. This causes the male’s brain to start looking more like a female clown fish’s brain. Now the changing dominant male will begin to exhibit more aggressive behaviors towards other fish--something female clownfish do.
The hypothalamus is an important part of the brain that regulates hormones. It connects to the pituitary gland that is located at the base of the brain and both organs are major components of the neuroendocrine organ system which is the organ system that controls how hormones are released in relation to how neurons in the brain react to a stimulus). Once the hypothalamus releases GnRH (Gonadotropin hormone-releasing hormone which tells the pituitary glands to release hormones) pituitary gland releases LH and FSH hormones into the bloodstream to the gonads through the hypothalamic-pituitary-gonadal axes. These hormones called the Luteinizing and Follicle Stimulating Hormones are gonadotropins, meaning they help control the gonads by stimulating ovulation in the transitioning male.
Receptors in the gonads receive the steroid hormones released by the pituitary glands. Currently, the gonad in the transitioning male is an ovotestis (ovary testis). The gonad receptors will then proceed to tell the connective tissues in the gonads to rearrange themselves. The testicular tissue in the gonads begins degrading while the ovarian tissues become more abundant as the ovaries begin to develop. The lack of DMRT1—a gene that controls the testicular germ cells which make up the sperm—causes the number of testicular germ cells to decrease while the amount of ovarian germ cells begins increasing, thus allowing for the production of eggs and the decreased production of sperm. The gonads will continue to help regulate the hormones in the endocrine system of the fish. This entire process of transitioning sexes in itself demonstrates emergence between the different cells and protein hormones which are relayed from the hypothalamus and pituitary gland to the different gonadal receptors and tissues making up the gonadal organs; the brain which controls the release of the hormones, and the neuroendocrine system, which houses all of these components in the clown fish’s change.
Since we now know that clownfish are sequential hermaphrodites (Protandrous ones to be exact), this changes the movie (probably for the worst). Our dearest Marlin’s wife Coral is dead along with his 399 unborn children, meaning that Marlin should be or is currently undergoing the process of transitioning from male to female. And since Nemo was the only one of the 400 eggs to survive, this leaves Nemo in the position of the dominant male. Now, this leads to the greater plot twist of the story, making the PG movie of Finding Nemo not so PG. So, kids, cover your ears, and parents, rethink your choices. As now to continue their species, Nemo and Marlin will have to—oh no.