Sunday, March 13, 2011

Creature Feature: Flounder.


We know what you're thinking: What could possibly be weird about the little yellow and blue fish that follows Ariel around? Don't tell us that beneath that cute exterior lies a flesh-eating piranha. You must have something else shocking up your sleeve.

Why, yes. Yes we do. 

Let's start with real flounders not looking like the cartoon fish. At all.

Similar in color only.

Real flounders (containing many families) look a lot more like stingrays at first glance. They are part of a group called flatfish, which also contains sole, halibut, and a few other delicious entrees. True to their name, flatfish are flat and spend much of their time on the bottom of whatever part of the ocean, estuary or lagoon they happen to be in. Some have been found fluttering along the bottom of the Mariana Trench, one of the deepest ocean trenches found to date. All are carnivorous, eating crustaceans and fish fry before being fried themselves.

After watching a flounder swim around for a little, one eventually notices something strange: Its spine undulates more like that of a dolphin than a fish. Also, wait a minute - is that a gill slit on top? And a fin? Oh, goddess, what did nature DO to this thing?!

Flatfish, flounders included, essentially swim on their sides. That is why the operculum and pectoral fin are clearly visible on top of the fish. Those raylike fins would normally be located along the fish's back and underside. Technically, they still are, but the way the fish is tilted makes it resemble a weird ray.

Creepier still is the flounder's strange but logical eye arrangement. Baby flounder start with one eye on each side of their heads like normal fish; as the fish grows, it not only starts to prefer swimming closer to the bottom, but that eye moves to one side of its face. The eye migrates to the right in some flounders and the left in others. If Picasso designed a fish, it would be a flounder.

Flounder are perfectly evolved for life along the ocean floor. Having their eyes on top lets them spot predators more easily. Somewhat rarely for fish, they can also change color. Whether they are on sand, rocks, or coral, the flounder will always blend in. Flounder can even camouflage themselves on checkerboard patterns.

Evolved for fashion?

This excellent camouflage cannot protect them from man. Flounder and other flatfish around the world are so tasty that they often get overfished. Atlantic Flounder and sole are both fish to avoid if one is looking for sustainable flatfish. We can't help you if you're looking for a tasty substitute (although the author particularly likes halibut).

Tomorrow: Malaria. No, this entry is not about mosquitoes.

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