“Here’s looking at you, kid.”
Would Clark Gable have said this to Ingrid Bergman with such panache if she’d been a flounder. Probably not, unless he was a flounder as well. (In which case, there’d probably be no movie). But if Ilsa and Rick were flounders, their first question to each other might well be “Are you right-eyed or left-eyed?”
For these flattened, bottom-dwellers this question is answered early on. Flounders are born bilaterally symmetrical, having an eye on each side of their head – and they swim near the surface of the sea.
During the larval to juvenile stage, flounders begin to lean to one side and the eye on that side begins to migrate to what will become the top of the flattened fish. Other changes occur in the nerves, bones and muscles, and the underside loses its colour.
In effect, flounders are fish that have decided to lie flat on the bottom of the sea-floor, and keep their two eyes on the top of their head.
It depends on the species of flounder whether the eye migrates to the left or right. The family Bothidae has over a hundred species of left-eyed flounders, and the family Pleuronectidae has a similar number of right-eyed flounders. Species from both families are found in Australian waters.
As adults, flounders camouflage themselves by varying their colour to blend into their environment. Flounders are demersal fish which means they live in deep water or on the ocean bed. They feed on prey such as small crustaceans and polychaete worms in the soft sandy, muddy areas in which they live.
Some flounders can camouflage their bodies and appear invisible to predators by digging themselves into the bottom, using their fins to deposit a layer of sand/mud over their bodies. Usually the only parts of the flounder that are visible are its eyes. If it is disturbed, the flounder will swim rapidly away whilst throwing up a screen of the bottom silt/sand around its body. Once it feels safe, the flounder settles back on the bottom and again becomes virtually invisible.
So next time you’re feeling low, maybe think about flounders, and soles, and stargazers and Oscar Wilde – and remember “ We are all in the gutter, but some of us are looking at the stars.”
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Photos: David Donnelly
Dolphin Research Institute