"Popular Science Times" Why are the eyes of flounders "crooked"

Image source wikimedia Commons

□ Hu Juntong

In the early 1990s, with the continuous efforts of Academician Lei Jilin, a famous marine fish farming expert in China, 200 Multi-treasure fish fry were carried by Dr. Howell, a British expert, and crossed the ocean to China. They are the "ancestors" of the multi-treasure fish on our table today. This is probably the most famous of the flounders.

The dobao fish , also known as turbot , is a marine benthic fish of the genus Turbot in the flounder family Offidopterae. Native to the Atlantic, they grow rapidly, tender and fresh meat, but also have high nutritional value. Therefore, duobao fish is used as an important breeding object in many countries. Although the introduction and cultivation of multi-treasure fish has taken a lot of trouble on scientists, including Academician Lei Jilin, today, they have become regular customers on our table.

As a member of the "family" of flounders, nothing is most memorable than their asymmetrical bodies. "There is a flounder in the East, but it is not better than no." Because both eyes of flounders grow on the same side of the body, the ancients mistakenly believed that they could only survive in parallel and dependent on each other. So, have they been "crooked" since childhood? Are all flounder eyes "crooked" to the left? Do they, who are always lying on the bottom of the sea, have time to escape when danger comes?

In fact, flounder fish commonly known as flounders include flounders, turbots, flounders, flounders, tongue rays and so on. Usually, the eye positions of fish in the same family are the same, but there is a more special family, fish in the family Shrew, and the number of individuals on the left and right is similar.

In fish taxonomy, there is a saying that "left turbot right flounder, left tongue fish right flounder". This means that the eyes that grow on the left are usually called turbots (such as turbots, turbots, etc.) or tongue rays (tongue fishes), while those on the right side are flounders (such as flounders and crested flounders) or trouts (troutidae). Based on this, we can quickly judge the species of flounder based on the position of the eye.

Of course, there are exceptions. Flounders are not born "crooked dates", and their eyes are on the same side of the body. However, when they have just hatched, they are actually like other fish, the body is symmetrical, and the two eyes are also on either side of the body. However, soon after birth, they begin to metamorphose, the skull begins to breed asymmetrically, and as the body continues to develop, they become more and more asymmetrical, and one of the eyes also constantly moves to the other side, and finally the effect of "flounder" appears.

Flounder is a master of disguise. As benthic fish, flounders are stationary on the seabed with one side of their body pressed against the seabed. They cling to one side of the seabed, like the belly of other fish, showing a uniform grayish-white color, while the side facing the sea is covered with patterns and spots to camouflage themselves. In general, most flounders disguise themselves in disguise, blend themselves with their hidden environment, hide themselves, and avoid predators. However, some flounders have a different approach, with obvious eye spots (such as the eye-spotted short-armed fish), while other small tropical fish are highly toxic, for example, leopard fish species contain leopard ray toxin.

Flounders are very inactive, so some species, such as the spotted proboscis, mimic as highly poisonous pseudo-horned planarians to confuse predators. However, the presence of leopard ray toxins also makes leopard rays a target for other biological mimesis, such as octopuses will merge their wrists, drag them to the back of their bodies, and swing their bodies up and down to mimic the highly poisonous leopard rays to escape predators.

After seeing such a peculiar "raw fish" experience of flounder, the next time you face the treasure fish on the table, will you have more feelings?

(Contributed by the Marine Science Popularization Professional Committee of the China Association of Popular Science Writers)