The common ones are two pliers with eight legs, and there are some special ones, such as King Crab, two pliers with six legs. There is a saying in Xunzi's exhortation: a crab kneels six times and pinches two times, but it is not a snake and eel that has no sustenance. It refers to this crab with six legs and two pliers.

A normal crab has eight legs that can walk, and two claw feet that can't walk. There are five pairs of appendages in the chest of crab, which are called pectoral feet. One pair of appendages in front is equipped with strong claws, which can be used for foraging. The other four pairs of appendages are crab's feet. Walking depends on these four pairs of appendages. Walking looks unique and interesting, and most of them walk sideways instead of straight ahead.

Extended information:

Body characteristics:

Although the crab is small, it has all aspects. After removing the hard shell of the crab, we can find that the body part of the crab is protected by a shell. These shield-like shells are called carapace by biologists.

The crab body is symmetrical left and right, which can be divided into forehead area, eye area, heart area, liver area, stomach area, intestine area and gill area. Both sides of the crab's body are connected by appendage. The appendages of the head are called tentacles, which have the functions of touch and smell. Some appendages have the function of mouth, which is used to tear food and send it into the mouth.

The crab chest has five pairs of appendages, which are called pectoral feet. A pair of appendages at the front are equipped with strong claws, which can be used for foraging. The other four pairs of appendages are the feet of crabs. The crabs rely on these four pairs of appendages to walk and move. They walk in a unique and interesting way, and most of them walk sideways instead of straight ahead. Except for monks and crabs, they walk straight.

based on crab tail? 2? Because of the characteristics of only walking feet and less participation in walking, a 6-legged lateral moving walking mechanism was developed by imitating the walking mode of crabs, and its motion characteristics were studied to meet the requirements of walking on rigid ground and soft ground involved in agricultural production.

Baidu Encyclopedia-Crab