Flatfish

benthic periscope
cloaked along the earth’s crust
then – flurried sand


The life of a flatfish (e.g., sole, flounder, halibut) is the opposite to that of the ugly duckling. Flatfish start life cute as a button – swimming about upright with an eye on each side of their heads. Then a metamorphosis occurs and the darling fry turn into flattened, asymmetrical “Picasso” fish with both eyes on one side of the body.

The side of the body with both eyes faces upward and is mottled, usually in drab colours that camouflage well with the ocean sediment. The other side of the body faces downward and is devoid of eyes and colour. Flatfish slink along the ocean bed, their bodies rippling like a windblown flag. A flatfish’s mouth ranges from a European flounder’s goofy smile to the toothy sneer of a California halibut waiting to snatch up an unsuspecting small fish for dinner.

What’s the deal with a flatfish’s eye meandering from one side of the body to the other as it gets older?

Paul Myers suggests flatfish are simply transforming from juvenile to adult form like many marine fishes, but in an exaggerated and peculiar way.

Initially larval fish (including larval flatfishes) drift in the pelagic zone (i.e., not the bottom, not the coast) eating zooplankton. Upright swimming and normal eye placement seems appropriate for this life stage. Eventually larvae settle down on their new homes, perhaps a coral reef, and metamorphose into miniature versions of adult fish. Flatfish will literally settle down onto the seafloor. As upright swimming is abandoned and pancake mode is engaged, normal eye placement may be a problem. An adult flatfish with two eyes on one side of the body would probably have better success hunting and hiding than an adult with only one eye.

I suppose now that I’ve looked at so many images of flatfishes, they aren’t that ugly. After all, my two eyes are also on one side of my body.

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