In people's minds, animals with shells tend to move less quickly. In the case of common shellfish, clams and clams bury most of their bodies in the sediment, sticking out "water pipes" to breathe and feed, while mussels and oysters stick firmly to rocks or shells of the same kind and live a lifelong fixed life. Even snails that can crawl around are not much faster than their relative snails on land.
However, there are exceptions to everything, and there is a shellfish whose motor nerves are very developed, which is simply the "athlete" in shellfish. These shellfish are no stranger to us, they are regulars at the dinner table - scallops.
Colorful "folding fan"
Scallops are a very common seafood species. Whether it's grilled scallops in a summer night food stall, steamed scallops from vermicelli at high-end banquets, or dried scallops sold in supermarkets, there are many scallops in our lives that offer delicious food. Attentive people may find that the same name is "scallops", their size and shape are not the same, why is this?
In fact, the scallops we are talking about are a collective term for the members of the bivalves of the mollusk phylum Pearl shellfish family. The entire scallop family contains more than 300 species that are widely distributed on the ocean floors of the world. Scallops are fan-shaped, and the "scallop" is the shell of the scallop with a ridge similar to the scallop bone; the "fan nail" is the shell top of the scallop, with protruding ears on both sides of the shell, like the end of the folding fan. Look for the shape of the folding fan, you will basically not recognize the wrong scallop.
As bivalve shellfish, the basic structure of scallops is similar to the previously mentioned clams, clams, and oysters, and the two shells are connected by ligaments at the tip of the shell. The shell is wrapped around the body of the scallop: the muscles used to close the shell The closed shell muscle, the digestive and reproductive glands that grow around the closed shell muscle, and the thin meniscus-shaped gills. In addition, the scallop's body surface has a coat film that closely adheres to the shell.
Scallops have different shapes. The size, shape and color of the ctenophore scallops, Ezo scallops and Sun moon shells commonly found in the Chinese market are different: the ctenophore scallops are small in size, the shells are diverse in color, and the radial ribs on the shell are thinner and prominent; there are also some small protrusions. The Ezo scallops are large in size, mainly light brown, and the ribs on the shell are thicker; the shell of the Sun and Moon shells has no ribs, but is replaced by smooth concentric circle patterns, one is reddish brown, the other is white, which is also the origin of its name.
"Lying to win" life
After the scallops are inhaled into the seawater, they rely on the gills to filter the planktonic algae and organic debris in the seawater. However, unlike those shellfish that hide in the mud and sand or are fixed on rocky reefs, scallops have chosen a special way of life, that is, lying on the bottom of the sea and living freely.
Morphologically speaking, when the scallops lie down, the left shell is on the top and the right shell is on the bottom, so people are also accustomed to calling the left shell of the scallop "upper shell" and the right shell "lower shell". The left shell is darker and the grain is obvious, and the right shell is lighter in color and the grain is not obvious, such as the sun and moon shell, whose reddish-brown color is the left shell, and the white shell is the right shell.
Scallops evolved this trait to adapt to life on the seafloor: their flattened body lies on the ocean floor, covered with sediment stirred up by the waves, and the patterned left shell can further blur its outline and reduce the probability of detection by predators. In addition, the rough left shell is more likely to attach small oysters, sponges and other marine life, which can also play a role in camouflage. With these disguises, scallops lie on the bottom of the sea, slightly open the shell, you can live a "lying win" life.
With great skill
To live in the dangerous sea, in addition to hiding themselves, you must also have the ability to perceive the surrounding environment, and scallops have formed their own unique perception methods in evolution. The coat membrane of the scallop has many protrusions near the edge of the shell, as if it has a circle of "eyelashes". These protrusions are like tentacles, in addition to controlling the seawater flowing into the shell, they can also sense the vibrations As soon as they perceive danger, the scallops quickly close the shell.
Also at the edge of the mantle membrane of the scallops, if you look closely, you can also see a circle of evenly distributed dark blue or black dots. These dots are the eyes of scallops. They can sense changes in the brightness of light, but they cannot image them. When a predator approaches or swims over from above, the scallops can sense the direction the predator is in and react.
Turning off the shell is just one of the scallops' self-preservation skills. In times of crisis, they also have a unique escape trick, that is, swimming!
That's right, scallops can swim. When a great threat is felt, the scallops will rhythmically contract and relax the closed shell muscles, causing the shell to close and open rapidly. When the shell is closed, the mantle membrane is also closed, only the holes on both sides of the shell are open, and the water in the shell is quickly pressed out of the body, forming a reaction force that pushes the scallop forward; and when the shell opens, the mantle membrane also opens, and the seawater is quickly sucked into the body. Repeatedly, the scallops swim forward with the power of the spray of water, and can advance more than ten centimeters in 1 second. This can be regarded as lightning speed in shellfish.
In order to retain this escape ability, scallops have evolved developed closed shell muscles, which can weigh half the weight of the flesh. The closed shell muscle of scallops is also its main edible part, known as "shellfish" and "dried shellfish". When tasting delicious scallops, let's not forget that these are important organs that scallops use to escape!
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