Disney’s Finding Nemo. A 2003 childhood classic, full of laughs, tears and family bonding. Haven’t seen it? Here’s the whole plot.
And here’s an out of context, no spoiler version:
A serial killer brutally murders a mother (Coral) and almost all of her children while her husband (Marlin) watches, leaving only one child (Nemo) alive. The father raises his remaining son, who, because of the killer’s attack, is born with a physical impairment. One day, the son is taken from his father and kept as a prisoner in a foreign land. The father must travel far from home to find him and can only rely on the aid of a stranger (Dory) for help.
One small detail: they’re clownfish.
Now, that part isn’t so far-fetched. There are 2 species of clownfish endemic to Australia, Amphiprion percula and Amphiprion ocellaris. A. percula are known as “orange clownfish,” and live in the tropical waters of northeastern Australia, Papua New Guinea, the Solomon Islands, and Vanuatu. These are the fish you see in Finding Nemo. Their friends, the “false clownfish” or “western clown anemonefish” are found in the Indo-Malaysia region, from Japan through to southeast Asia, and Western Australia. They look the same (bright orange with 3 stripes) but have a distinct geographical distribution.
And, of course, it’s highly plausible that a clownfish could be taken by a diver as a souvenir. Depending on where in the Great Barrier Reef Nemo lives, Australian legislation says up to 5 shells, fish or invertebrates of any one species can be collected by hand or a handheld implement. Anemonefish collection is limited to research purposes only, so I guess that means P. Sherman was doing something illegal. Unfortunately, it’s pretty common – clownfish make up 43% of the global ornamental trade.
So that’s accurate.
What’s also accurate are the anemones. Clownfish and anemones have a bit of a you scratch my back I scratch yours thing. In science, this is called mutualism – a relationship where both organisms are mutually benefited. In this case, the clownfish get the protection of the anemones, and any food the anemone catches, and the anemone gets extra nutrition from the clownfish’s waste, as well as increased gas exchange from increased water flow caused by the clownfish’s movements. It’s a small housing market, though; orange clownfish live exclusively in 2 species of anemone, Stichodactyla gigantea and Heteractis magnifica.
Now here’s what’s not so accurate, and the reasons Nemo probably needs therapy:
Marlin and Coral are weird
Clownfish are social creatures, mostly by ecological choice. They live in groups of between two to seven fish, depending on the size of their anemone. These groups tend to be made up of a dominant female, a dominant breeding male, and a collection of non-breeding, undifferentiated clownfish.
Interestingly, these fish decrease in size depending on their position in the group. The female is the biggest, then the breeding male, then each fish based on their rank, with the subordinate fish maintaining a defined size difference between each rank.
In an experiment by Peter Buston, rank 2 fish were removed from the study group, which saw the fish in rank 3 increase in size to fill the rank 2 position. If the subordinates get too close to the size of the breeding pair, the dominant fish has been known to evict or kill the oversized fish, as it’s seen as a potential challenger to the dominant’s position (why? Because the dominant has nothing to gain by having the subordinates hanging around, while the subordinates have the potential for the ultimate prize: being part of the breeding pair)
Not only are Marlin and Coral the same size… but they’re ALONE. No random roommates.
They’re alone… and they have no neighbours
Maybe, you say, all those non-breeding clownfish have spread out along the reef and gotten themselves a nice little 2-bedroom anemone with an ocean view.
Well, maybe. But remember the small housing market?
In the wild, clownfish group together in little “families” because of ecological constraints. See, it’s weird for animals to hang out together for no reason. In the animal world, the meaning of life is to have offspring that can go have their own offspring and carry genes. To have all these fish hanging around not breeding seems counterproductive, so there’s got to be a pretty good reason.
In this case, it’s because the housing market isn’t just small, it’s horrible. There are juvenile clownfish coming in from other settlements, and a low mortality rate because the anemones do such a good job of protecting the clownfish. Start your own settlement, you say? Well, here’s the thing – clownfish don’t swim too good, which makes them easy prey. A study by Branconi et al found that given the choice to move between anemones set at increasing distances, very few clownfish moved, preferring to wait their turn to breed in favour of known anemones, familiar fish, and larger groups of fish.
Coral would NOT have cared about her eggs
In the clownfish world, males are the primary caretakers of their eggs, and both non-breeders and dominant males have shown they’re awesome dads; it’s been observed male clownfish will even stepfather eggs that are not theirs (which is super cool, because the males are guarding eggs they get no benefit from – pretty unusual in the animal world).
With the ability to lay thousands of eggs year-round, it’s unlikely Coral would have sacrificed herself to save one clutch.
Marlin should’ve eaten Nemo
Damaged or infertile clownfish eggs are typically eaten by the dominant male. Food is energy, and energy is important.
But it’s okay, Nemo would have been an egg and probably wouldn’t know any different.
And on that (lovely) note, we end part one.
Feeling traumatised yet? No? Don’t worry – part two is out next week, and it’s even worse.
