From the perspective of the "phylum" category of biological taxonomy, crayfish are insects. From the perspective of the "order" classification level, crayfish are "shrimps". It is shaped like a shrimp and has a hard shell. The adult body is about 5.6~11.9 cm long and dark red. The body of juvenile shrimp is uniform gray, sometimes with black ripples, and the pincers are long and narrow.