Crayfish (scientific name: Procambarus clarkii): also known as Procambarus clarkii, red crayfish and freshwater crayfish. Shaped like a shrimp with a hard shell The adult is about 5.6~ 1 1.9 cm long, dark red, with nearly black carapace and wedge-shaped stripes on the ventral back. Young shrimps are evenly gray, sometimes with black ripples. Long and narrow claws. The middle part of the carapace is not separated by a mesh gap, and there are obvious particles on the carapace. The frontal sword has a lateral thorn or a notch at the end of the frontal sword.
It is a kind of freshwater economic shrimp, which is widely welcomed by people because of its delicious meat. Because of its omnivorousness, fast growth and strong adaptability, it has formed an absolute competitive advantage in the local ecological environment. Its feeding range includes aquatic plants, algae, aquatic insects and animal carcasses. When food is scarce, they also kill each other. In recent years, crayfish has become an important economic species in China. In the process of commercial farming, it is necessary to prevent escape, especially to enter untouched original ecological water bodies. It has caused devastating damage to the ecological competitive advantage of local species.
Crayfish has been eaten in the United States for hundreds of years, and the sales of crayfish have gradually moved from country fairs to large-scale transactions. Crayfish is a very common cooking ingredient in the United States. Usually cooked with potatoes and corn, seasoned with kajiang powder. 98% of the edible crayfish in the United States are produced in Louisiana. Louisiana even selected crayfish as the state representative animal in 1983, and held the "Crawfish Festival" every year.
There are rumors that although heavy metals and oil stains are not the feeding objects of crayfish, these "toxic" substances can attach to food and enter the lobster. The "poisons" in lobsters will not be excreted, but will gradually accumulate, so in a seriously polluted environment, the heavy metals in crayfish will exceed the standard.
Crayfish can live in heavily polluted places, but most of the heavy metals it ingests are transferred to its shells. With the continuous growth and shelling, these heavy metal toxins are excreted, so the heavy metals in meat may not exceed the standard. The research data show that most of the heavy metals in crayfish are concentrated in the head except the shell, and the heavy metals in the tail we eat are not much, which is unlikely to cause poisoning.