Flatfish, belonging to the Pleuronectiformes family, live lying on the sandy bottoms of all the seas in the world. To this group belong numerous edible species, such as the rooster or sole.
Do flatfish have any differentiating characteristics with other species?
When they leave the egg, flatfish look the same as typical fish, which is known as bilateral symmetry. However, they soon lean to one side and compress laterally.
The eye of the lower face begins to move to the other side, in a kind of migration. That ventral side is “blind”, loses the pigment and becomes pale. In some species even the mouth is twisted up.
Before many weeks have passed, the flatfish has completed the remarkable transformation that empowers it for a benthic existence. More than 500 species constitute this important group of oceanic fish distributed throughout the world.
Other characteristics of flatfish
Most flatfish are small and they live lying at the bottom of surface waters or of moderate depth. Occasionally they jump to catch other fish, crustaceans, worms or other animals they feed on.
The females of flatfish lay numerous eggs that float adrift until the birth of the offspring.
When starting to swim, to do so very quickly, almost all fish use jet propulsion, strongly expelling water from the gills. This shoots them forward.
Flatfish often use this method to escape instantly. The moment they do it, it seems as if there has been an outburst in the background. And, when the dust raised by his departure settles again, the fish has lost sight.
What are the flat fish best known to humans?
The flounder
This fish is the smallest flatfish in the world. There are few that measure more than 25 centimeters.
One of their most unique characteristics is their ability to change colors to be confused with the surrounding environment. This feature is not exclusive to sole, however it is one of its best representatives.
A blind sole always maintains the same color, whatever the background on which it is placed. Instead, in normal situation, He is able to imitate the color around him with remarkable perfection.
On a sandy bottom acquires a brown-yellow tone. But the moment he moves to a dark background, his skin turns black. And even more remarkable: if nothing about a spotted sector of dark and light tones, its skin also forms diverse spots.
In addition they are not limited to imitate neutral colors. They can acquire reddish, yellow or green tones.
How do they get these color changes?
Normally a sole has a white ventral face because all its pigment cells are located in the dorsal face. But a specimen placed in a glass bottom aquarium, soon acquires pigmentation also on that ventral face.
The hypoglossal fish, one of the largest flatfish
The hypoglossus seeks food by chasing small fish through the open sea. It is a fast animal and Spend less time than other species lying waiting for food to pass over it.
The turbot
The turbot is another large fish that can reach up to 1 meter in length and 25 kilos in weight. His eyes are on the left side, so that he rests at the bottom of the sea on his right side.
On the contrary, the sole, flounder and limanda rest on its left side.
Turbot is one of the most prolific marine fish. The female lays up to 10 million eggs in a square millimeter. However, they are very vulnerable and few reach adults.
Final note
Did you know all this data about flatfish? Undoubtedly, these can be very curious animals, for various reasons, so they are far from being another issue.