We as humans tend to be oblivious of the world around us except when things peak our interest. For example, I love the shooting sports, and so naturally I am aware of the firearm culture in movies and how they are portrayed. Sometimes Hollywood gets it right and sometimes they badly miss the mark (we’ve all seen that 6 shot revolver mysteriously fire that seventh round). For me, the same is true with fish. Disney released Finding Nemo in 2003, and shortly after that everyone knew the clown fish (Amphiprion spp) as Nemo. This isn’t a bad thing because it introduced kids to fish and stimulated an interest in ichthyology. However, there are certain things that are incorrect with Nemo. I will address a few so let me begin…
Problem 1. As weird as it might seem hermaphroditism is quite common in the fish world. This phenomenon can be divided into two distinct types – protandry and protogyny. These processes are called sequential hermaphroditism which means the fish is first one sex then transitions to the opposite sex as a result of some cue, signal or event. Protandry is a situation in which the fish is first a male then a female, and protogyny is just the opposite – first female then male. There have been several mechanisms proposed as to why this occurs in nature, but I’m not entirely sure we will ever know. The fact is that it happens and it suits the survival of certain species quite well. Believe it or not our friend, Nemo, is a poster child for protandry hermaphroditism. Within a clownfish community there is typically a single breeding pair with the female being larger than the male (this is yet another problem because in the movie I believe Nemo’s mother, Coral, is portrayed as slightly smaller than his father, Marlin). The rest of the members simply carryout their daily lives with no functioning gonads. If the female dies, the breeding male transitions to the breeding female, and the next largest non-breeding member becomes the breeding male. Balance is restored. So now that we understand this process let me put this in the context of Nemo. In the beginning of the movie, Nemo’s mom is killed and all that is left is Nemo and Marlin. Now, if Disney had been aware of the biology of clownfish then what we should have seen was Marlin transitioning to the breeding female, and since no other clownfish were alive Nemo would have become the breeding male. This puts a weird twist on ole Nemo and his dad.
Problem 2. The antagonist at the beginning of the film appeared to be a great barracuda (Sphyraena barracuda). It is unlikely that a barracuda would be bothered by eating a clownfish and its eggs. The energetic demands of a fish such as the barracuda is much higher than the caloric content of a lowly clownfish and its eggs.
Problem 3. Nemo ultimately gets captured and placed in an aquarium with other fish. Among his new friends is a fellow by the name of Bloat. Bloat is a long spined porcupine fish (Diodon holocanthus) that can be found in tropical and subtropical regions throughout the world. They have an interesting tooth structure allowing them to feed exclusively on invertebrates. Yes, invertebrates. Remember Jacques the shrimp? I’m not entirely sure he should be in the same tank as a porcupine fish unless he was put in there as a snack. Sorry, Jacques.
Problem 4. There are three types of muscle found in the piscatorial realm – white, pink and red. Red muscle is red in color due to a high volume of myoglobin (a type of iron and oxygen binding protein) and usually thin in structure. They depend on aerobic metabolism and oxidative phosphorylation for the production of adenosine triphosphate (an energy source) to produce slow and sustained movements. Without the buildup of lactic acid, these muscle groups are needed to perform for longer periods of time without fatigue. These characteristics in addition to high levels of mitochondria, make red muscles ideal for highly migratory species such as tuna (Family Scombridae). White muscle is quite the opposite. While their color is a result of lower concentrations of myoglobin, they are much thicker than their red counterparts and utilize anaerobic metabolism and glycogen to perform fast, powerful contractions synonymous with sprinting. Because of the lactic acid build up as a byproduct of glycolysis, white muscles are only suitable for short durations before fatigue sets in. The final type of muscle is pink muscle. As its name suggests, it is an intermediate muscle type that is a blend of the white and red muscle types.
In the movie, Marlin travels hundreds of miles to find Nemo. This may seem plausible, but in reality it really isn’t. Although I have never dissected a Nemo fish, I am willing to bet it has white muscles. In order to perform an extensive migration like Marlin did, red muscles would be needed to make the trip in the time frame he did it in. White muscles just wouldn’t be suitable. Besides, red muscles aren’t required for life inside an anemone.
Problem 5. Fish don’t talk…
Hopefully, the next Disney fish movie will be a little more accurate and appeal more to the ichthyological crowd.
(Photo credit: http://www.aqua.org/explore/animals/clownfish)