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.

The shape is large and cylindrical, the shell is firm and thick, the head and breastplate are slightly flat, the front edge does not heal with the front plate of the mouth, and the side edge does not heal with the abdominal shell of the chest and the base of the chest limb, except for crayfish. The neck groove is obvious. The antenna 1 is short and small, Shuang Bian. The second antenna has grown scales. All three pairs of jaws and feet have external limbs. The feet are all single-branched, and the first three pairs are chelated, among which 1 pair is particularly strong, so it is also called crayfish. The last two pairs of feet are simple claw-shaped. Gills are filamentous gills.

There are three pairs of tentacles on the head of crayfish, which are thick near the head and small and sharp at the top. A pair of tentacles on the outer edge of the head are particularly thick and long, generally longer than the body1/3; Between a pair of long tentacles are two pairs of short tentacles, which are about half the length of the body. When resting and crawling normally, all six tentacles extend forward. If frightened or attacked, two long tentacles will bend to the tail to prevent the tail from being attacked. There are five pairs of feet in the chest, 1-3 pairs of feet end with pliers, and 4-5 pairs of feet end with claws. The second pair of walking feet are particularly developed and become very large claws. The claws of male lobsters are more developed than those of female lobsters, and there is a bright red film on the front outer edge of male lobsters, which is very conspicuous. Females do not have this red membrane, so this is an important feature that distinguishes males from females. There are five powerful tail fans at the tail. During the incubation period and incubation period, the tail fan of the mother shrimp bends inward, crawls or is attacked to protect the fertilized egg or young shrimp from harm.