Swimming crab, commonly known as "white crab" in some places. Because the breastplate is spindle-shaped, it is named spindle-shaped. There are three protrusions in the center of the crustacean, so it is also called "Portunus trituberculatus" and belongs to arthropods. The male umbilical cord is smooth, the claws are long, and the shell surface is blue; The female umbilical cord is round and fluffy, and the shell surface is ochre or spotted. Portunus trituberculatus has delicious meat, high nutritional value and economic value, and is suitable for temporary cultivation and fattening in seawater. The head and breastplate are spindle-shaped, and the width is almost twice as long; The surface of the head and breastplate is covered with fine particles, with 2 lateral ridges and 3 verrucous protrusions; There are two sharp teeth on the forehead; There are 9 sharp teeth on the front side edge, and the back teeth are long and prickly and protrude outward. The pliers are thick and longer than the breastplate of the head. The long section is prismatic, the male long section is slender, and there are four spikes in the front edge.