Crabs are crustaceans. There are thousands of different types of crabs, divided into more than 850 species. Most kinds of crabs have a hard shell (called exoskeleton), three walking legs on each side of their bodies, and two claws.

Crabs are symmetrical and can be divided into forehead area, eye area, heart area, liver area, stomach area, intestine area and gill area. Crabs have appendages on both sides of their bodies. The appendages of the head are called antennae, which have the functions of touch and smell. Some appendages have the function of mouth, tearing up food and sending it into the mouth.

Crab chest has five pairs of appendages, which are called chest feet. A pair of appendages at the front end are equipped with strong limbs and can be used for foraging. The other four pairs of appendages are crab feet. Crabs rely on these four pairs of appendages to walk and move. They walk in a unique and interesting way, mostly sideways rather than straight. Except monks and crabs, they all walk straight.

Species of crabs

1, rare crab

Treasure crab, also known as treasure crab and steamed bread crab, is a kind of crab produced in the United States and belongs to the important resources of local aquatic products. Its size is large, its back shell is about 16 cm long and its weight is about 500 grams. Moreover, only male treasure crabs can be caught, and female treasure crabs are mostly used for breeding.

2. Portuguese fish

Portunus trituberculatus is named after its back shell is shaped like a shuttle and belongs to arthropods. The navel of male Portunus trituberculatus is sharp and smooth, and the color is blue. The navel of female Portunus trituberculatus is round and fluffy, and the color is brown, which is generally distributed in most coastal areas of China.

3. Red crab with red nails

Red-breasted red crab is a kind of sea crab, named after its red abdomen. Its head and breastplate are oval, hard and aggressive. Generally, it is active in low-tide rocky areas and algae-dense areas, and the production season is concentrated in April-May and September-10 every year.