Shrimps and crabs are invertebrates, belonging to the Decapoda order of the Crustacea of ??the phylum Arthropoda. Most of the species are marine. There are not many species distributed in fresh water. Shrimps and crabs are covered with a layer of carapace. The carapace of shrimp is soft and tough, while the carapace of crab is hard and brittle.

Shrimps and crabs are delicacies on people’s tables, and they all belong to the Crustacea. my country is rich in shrimp and crab resources. Among the shrimps, hairy shrimps, prawns, and macrobrachium, and among the crabs, swimming crabs, blue crabs, and river crabs are all nutritious foods that people are familiar with. In addition, there are many small

crustaceans (such as water fleas) that serve as food for fish.

Macrobrachium Macrobrachium Macrobrachium lives in lakes and rivers, usually crawling on the sand at the bottom of the water, but it also often clings to aquatic plants or

rocks.

The body of Macrobrachium is green, so it is also called green shrimp (picture below). The body of Macrobrachium is composed of cephalothorax and abdomen. The head that we usually refer to as Macrobrachium is actually its cephalothorax. The surface of the cephalothorax is covered with a tough cephalothorax. In front of the head and breastplate, a saw-toothed sword-shaped protrusion protrudes, called the forehead sword, which is a weapon used to defend and attack enemies. There is a pair of compound eyes, which are born on the handles on both sides of the forehead sword that can rotate freely. They are used to observe the surrounding situation. There is one pair of large tentacles and one pair of small tentacles. The tentacles have the functions of touch and smell. On both sides of the head and chest, there are leaf-like gills, which are respiratory organs.

There are 5 pairs of slender legs on the ventral side of the cephalothorax of Macrobrachium. The first two pairs of legs have pincers at the ends. The first pair of claws is very small and used to clamp food

; the second pair of claws is very thick, often exceeding the length of the entire body, and the claws are large and powerful and used to defend or attack enemies. ;The rear

three pairs of claw-like legs are used to cling to aquatic plants or other objects, or to crawl on the bottom of the water. The five pairs of swimming legs on the abdomen of Macrobrachium can only assist in crawling or swimming short distances.

Female shrimps mostly lay eggs in the summer. The eggs are not laid directly in the water, but are attached to the swimming legs of the female shrimps and do not leave until the larvae hatch.

In this way, the fertilized eggs can be protected by the mother, and the hatching rate is relatively high.

The body of a crab is also divided into a cephalothorax and an abdomen. The cephalothorax has an obvious cephalothorax (picture below). The abdomen of the crab is folded under the cephalothorax and is called the navel (the navel of a female crab is round, and that of a male crab is triangular). Therefore, although shrimps and crabs have very different shapes, they both belong to the Crustacea class.

The main characteristics of Crustacea. Shrimps, crabs and other animals all belong to Crustacea. Their common characteristics are: the body is generally divided into cephalothorax

and abdomen, and the surface of cephalothorax It is covered with a tough head and breastplate and has two pairs of antennae. Most of them live in water and usually breathe through gills.