The flounder has an unusually flat appearance that’s well-suited for its bottom-dwelling lifestyle. To see everything above it, the flounder has two big round eyes projected from small stalks on the same side of the head. These eyes also have the ability to move independently of each other. The typical flounder specimen measures somewhere between five and 25 inches in length (the larger ever recorded was some 37 inches) and up to 22 pounds in weight. This doesn’t quite capture its true size, however, since the flounder has a massive surface area thanks to its round or oval body.
The flounder’s scales act as camouflage that makes it difficult for both predators and prey to detect it against the muddy or sandy ocean bottom. Some species can actively change their color to blend in with the seabed. This has the dual purpose of also signaling the emotional state of the fish. For instance, a pale color may be a sign that the creature feels threatened. The flounder comes in a huge range of different colors and patterns, depending on the composition of the sediment in which it resides. The slate of orange, brown, green, white, or tan colors is normal.
WHAT’S THE DIFFERENCE BETWEEN A FLUKE AND A FLOUNDER?
Flukes and flounders are types of flatfish. That means that, while they started life swimming upright, during the larval stage, they lay on either their left or right side and the eye facing towards the bottom migrated to be top-facing.
So, some flat fish are right-side-up (their left eye migrated to the right side) and some are left-side-up, meaning that their right eye migrated to the left side. What makes a particular fish turn into a left-side or a right-side fish?
ALL FLUKE ARE FLOUNDER BUT NOT ALL FLOUNDER ARE FLUKE
Generally speaking, left-side up flounder are flukes, and right-side up flounders are called flounders. That sounds easy enough to remember, but it gets worse. Flukes are also called “summer flounder,” and flounder, or right-side fish, are called “winter flounder.”