Crabs spend most of their time looking for food and are generally not picky eaters. They can eat all the food they can get. Small fish and shrimp are their favorite, but some crabs eat seaweed, even animal carcasses and plants.

Crabs eat other animals, and other animals may eat crabs. For example, humans regard crabs as delicacies, and waterfowl also eat crabs. Some fish like to eat crab feet just like humans. Young crabs and underage crabs may be preyed by other marine life when floating in the sea in groups, so crabs should lay a lot of eggs when laying eggs to ensure the survival rate of crabs.

Crabs are symmetrical and can be divided into forehead area, eye area, heart area, liver area, stomach area, intestine area and gill area. The two sides of a crab are connected by appendages. 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.