Spiders have not evolved. It belongs to the family Crab, belonging to the same class as spiders, not an order. Crab evolved from shrimp. Shrimp is a slightly lower arthropod.
Evolutionary history Arthropods evolved from annelids, such as arthropods. The nervous system is chain-shaped, and the structures such as green gland, jaw gland and renal duct are homologous to the catheter of body cavity. The leaf foot is similar to wart foot, and the circulatory system is on the back of digestive duct. There are different opinions about whether the ancestors of arthropods are unitary or pluralistic. Those who advocate the origin of monism believe that the ancestors of annelids evolved into primitive arthropods similar to trilobites, and then divided into two branches, one evolved into crustaceans, polypods and Insecta, and the other evolved into arthropods and arachnids. Some people also use the method of cladistics to divide hexapod, polypod and claw into a single line, and crustacean, chelopod and trilobite into another single line, which is a sister group. According to different larval segments, it is considered that there may be many origins.
Three origins, that is, crustaceans have one origin, trilobites, arthropods and arachnids have the same origin, and polypods and Insecta have other origins.