Imbedded in an interesting article about the role and history of aquaria in fish conservation, I found an aside about the movie Finding Nemo. It wasn’t entirely accurate ("No!", you say to yourself. “Yes, it’s true,” I sadly inform you.)

In a crucial scene of the movie, Nemo’s mother and his unhatched siblings are eaten by a barracuda. Nemo is the lone larva to survive. Nemo’s father becomes an overprotective worrywart after the disaster, and both quite evidently miss Nemo’s mother very much.



The trouble with all this understandable humanizing of the characters is that in nature, clownfishes are protandrous hermaphrodites. What that means is that they start life as males, but under certain circumstances become females. Typically an adult pair—a female and a male—and between two and four smaller fish live together in a single anemone. The dominant, largest fish is generally a female. She possesses functioning ovaries and degenerate testicular tissue. The next-largest fish has functioning testes as well as some latent ovarian cells. If the dominant female dies, her mate’s gonads cease to function as testes and the egg-producing cells become active. Simultaneously, the largest of the non-breeding individuals becomes the functioning male.



So, had Marlin, Nemo’s dad, just hung around for a while, he would have become a she and Nemo would have had his mom back. Then with time, Nemo himself would have matured into a functional male and...but perhaps that’s all a bit too dark for the story line.

I enjoyed Finding Nemo as it was, but Pixar really passed up an opportunity for a much more fascinating movie.

Stiassny, MLJ (2004) Saving Nemo. Natural History 113:50-55.