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1, 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.
2. Morphological characteristics
The body shape is cylindrical. Crustaceans are solid and thick, with a slightly flat head and breastplate. The leading edge does not heal with the anterior plate of the mouth, and the lateral edge does not heal with the abdominal shell of the chest and the base of the thoracic 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.
The head of crayfish has three pairs of tentacles, 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.