I. Example sentences

1、Clinical? signs? of? bacteremia? in? freshwater? crayfish? are? non-specific? and? typically? are? limited? to? increasing? apathy? and? paralysis? immediately? prior? to? Death. Clinically, the bacteremia of crayfish is nonspecific and typical, with mental retardation, paralysis and immediate death.

2、There? are? more? than? 540? species? of? crayfish? in? the? world.Crayfish? are? widely? natively? distributed? in? the? world? except? Africa? and? Antartica. There are more than 540 species of freshwater crayfish, which are widely distributed all over the world, except Africa and Antarctica.

3、We? don't? have? oysters? tonight,but? the? crayfish? are? very? We good't have oysters tonight. But crayfish are very good.

Second, crayfish

1, crayfish, is an arthropod belonging to the genus Macrobrachium of the Decapoda family. Crayfish has a hard shell; Body colors include red, reddish brown and pink, and the back sauce is dark red; There is a wedge-shaped stripe on the back of abdomen; Long and narrow; Claws are dark red and black with bright orange or reddish nodules; The head center is long; The body is large and cylindrical; Filamentous gills; There are tentacles on the head

2. The shape of crayfish is similar to that of seawater lobster, and the individual is smaller than seawater lobster, hence the name. Crayfish originated in northern Mexico and southern United States, and now it is widely distributed in more than 40 countries and regions, and also widely exists in all parts of China, especially in the middle and lower reaches of the Yangtze River. Crayfish mostly inhabit rivers, lakes, ditches, ponds and rice fields.

Third, the morphological signs

1, the body is large and cylindrical, the carapace is firm and thick, the head and breastplate are slightly flat, and the front edge does not heal with the anterior 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 the crayfish family. The neck groove is obvious. The first 1 antenna is short and small, Shuang Bian.

2. The second antenna has developed scales. All three pairs of jaws and feet have external limbs. All the steps are single-branched, and the first three pairs are chelated, among which the first pair 1 is particularly strong and thick, so it is also called crayfish. The last two pairs of feet are simple and claw-shaped. Gills are filamentous gills.