The poisonous sand crabs include the copper-cast crab, the patterned crab, the embroidered-ridged crab, the scaly crab Nocardia, and the Leijin crab, as shown in the following pictures:

1. The copper-cast crab: this crab belongs to the fan crab family, with an oval head and breastplate shell, obvious back bulge and smooth surface. It is mainly distributed in rocky reefs or coral reefs in tropical and subtropical waters such as the Indian Ocean and the Western Pacific Ocean.

2. Pattern-loving crab: The common name is flower steamed bread crab, which belongs to the fan crab family. Its head and breastplate shell are transverse oval, its back is very bulging, and its surface is smooth.

3. Embroidered spine is ripe like a crab: this crab belongs to the family Crab, and its head and breastplate shell are transverse oval with smooth surface. The knuckles of pincers' feet are black, and each knuckle of pincers' feet is wide and flat with bunches of bristles. The whole body is in red and white net pattern, and the nail is about 5 cm long and 9 cm wide.

4. Scallop Norris: This crab belongs to the family Crab. Its head and breastplate shell are pentagonal, with two leaves on the forehead and an inverted triangle notch, and there are scaly or obtuse round particles on the surfaces of the claw feet and the head armor.

5. Leijin Aijie Crab: This crab belongs to the family Crab. Its head and breastplate shell is oval, with dense particles and short bristles on its surface, and its back is reddish orange to dark red. Fingers of pincers are black.