Ask the Aquarium - Flounder need those freaky eyes
Published: Thursday, July 11, 2013 at 8:00 p.m.
Last Modified: Thursday, July 11, 2013 at 11:57 a.m.
Q My daughter and I are new to fishing and recently caught a flounder. It had both eyes on the same side of its head. Is that normal?
A. Yes. Flounder are a type of flatfish that spend most of their time buried in the sandy sea floor with only their eyes protruding.
Having both eyes on the same side of their heads is helpful for their sly, ambush-hunting technique. The eyes swivel independently like small turrets, increasing their chances of catching a small, unwary fish, shrimp or crab passing by.
Burying also helps keep them from becoming a meal for a neighbor or a hungry predator.
A flounder begins life looking like any other fish – swimming upright and with an eye on each side of their head. At about 5 weeks old, one eye actually begins to migrate across its head until it's next to the other eye. Also during this time, the young flounder begins to lean more and more to one side and soon develops its characteristic pancake-like shape and fluttery, undulating swimming style.
Flounder have another remarkable characteristic – they can change color and patterns in a flash. Although creamy white on their flat underside, the flounder's top side is covered with pigment-bearing cells. These cells can change both color and pattern, going from light to dark and from dots to irregular-sized blotches in a wide variety of colors and shapes. With this excellent camouflage ability, a buried flounder becomes almost invisible on the sea floor.
But how does the flounder determine what color and pattern to use?
Surprisingly, flounder have remarkable color vision. Researchers tested flounder against a variety of backgrounds, including a checkerboard pattern, and were astonished at how effectively the fish succeeded in matching their environments. The fish instinctively scanned its surroundings and its brain adjusted the pigment cells to implement an astounding variety of colors and shapes. A blindfolded flounder doesn't change color at all.
For a look at this common but complex change artist in its natural habitat, check out www.youtube.com/watch?v=h72UXY2PHD0.
Information provided by the N.C. Aquarium at Pine Knoll Shores. The state operates three public aquariums; one in Pine Knoll Shores, another at Fort Fisher and a third on Roanoke Island, as well as Jennette's Pier in Nags Head. The facilities are administered by the N. C. Department of Environment and Natural Resources and are designed to inspire appreciation and conservation of North Carolina's aquatic environments. For more information, log onto ncaquariums.com, or call 800-832-FISH.
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