Eye Travel

Try crossing your eyes or move them independently. How about move either one of them to say, the back of your head. It is a neat trick if you could, right? Who does that you ask?

Before I tell you the answer, and you know I will, I would like to ask you to think of any animals that change in terms of shape or in other words, undergo metamorphosis. Now, can you think of any of these animals, which as infants, have the ability to perform such tricks I was talking about?

I am talking about the flatfishes, the likes of flounder, halibut, sole, plaice, dab and turbot, just to name a few. These flatfishes belong to the Pleuronectiformes order that contains over 500 species. As adults, they have both eyes on one side, which is the upward-side of the head - a possible source of inspiration to Pablo Picasso. To fish-lovers, you have probably known about this but, I had always thought that flatfishes were originally born that way. I was wrong.

Like some other fishes, a female flatfish will release its eggs, about millions of them, into the water which will then be fertilized by the male. This will float around for a few days and then hatched into symmetrical, vertically-aligned young fish called larvae. This is the most important stage of a flatfish's life. When the larvae is about 1-2 centimeters long, the fish will begin to become oriented horizontally. The skull will become greatly compressed. The face will become twisted and permanently facing upward along with the mouth; in some species, the mouth will remain 'normal'. One eye will migrate to the other side of the head which will then become the upper side of the fish. Specifically, in some species one eye will travel over the top of the head and in some other species, directly through the skull. Once settled, the eyes can be moved independently enabling the fish to see in all directions except what is below.

Some other common characteristics of flatfishes are, they are obviously flat, prefer to live on the seabed and feed on small marine animals. Their hidden side is usually white in color; making them hard to spot from below, and their upper side is, lacking of other non-animal words, chameleon-like. Many of them have the ability to change their pigmentation to match their surroundings. Notably, those living on sandy bottoms have light brown upper sides and those living on pebbled bottoms have spotted upper sides. To make themselves even less visible, they will disturb the sand and blend seamlessly with the sea floor. Apparently, having compressed skulls does not mean lack of creativity.

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