The crab has 10 legs because it belongs to the Decapoda order of arthropod mollusks, and its body is divided into a cephalothorax and an abdomen, with five pairs of thoracic feet on either side of the cephalothorax, or ten legs, two of which are chelicerae (pincers).
General crab is two pincers eight legs, there are special, such as king crab, two pincers six legs. Normal crabs have eight legs that can walk and two chelicerae that do not function as walkers. Crabs have five pairs of appendages on their thorax called thoracic peduncles. The front pair of appendages is equipped with strong chelae that can be used for foraging. The other four pairs of appendages are the crab's feet. With these four pairs of appendages, the appearance of walking is unique and interesting, mostly walking sideways rather than straight ahead.
Crab Habits
Ninety percent of crabs are seafood and the rest are freshwater. Among the marine crabs, such as sheep crabs, Guan Gong crabs, frog crabs (Ranina), bun crabs (Calappa), etc. live in the subtidal zone at different depths; such as pike crabs live in the shallow sea; the square crabs (Grapsidae), sand crabs (Ocypodidae), and most of the scalloped crabs (Xanthidae) mainly live in the vast intertidal zone; a very small number of species such as drifting crabs (Planes) and the bowhead crabs (Xanthidae) mainly live in the vast intertidal zone; very few species such as the drift crabs (Planes) and the bowhead crabs (Planes). Planes) and bow crabs (Varuna) can live attached to wood or other floating objects in the ocean.
The vast majority of crab species are omnivorous. For example, the intertidal Sesarma crab (Sesarma) feeds on carrion as well as animal carcasses and small animals. There is also a significant portion of the crab for carnivorous, such as the pike crab (Portunus) can eat fish, shrimp and mollusks and so on.