The order Arthropoda is divided into several suborders.
1. Trilobitomorpha: These are invertebrate arthropods. Their exoskeleton is strong. They are the most diverse.
2. Crustacea: Their bodies are soft and three-layered. Real Siloam exists. Has two pairs of antennae. Has two compound eyes. The body is divided into segments. For example – Bagda shrimp (Penaeus monodon).
3. Calicerata: These are eight-jointed joints. The body is divided into head and torso. They don’t have wings. There are poison glands in the body. For example – Spider (Lycosa lenta)
4. Hexapoda: Their body is chitinous and divided into head, thorax and abdomen. The thorax has a pair of jointed legs and a pair of wings. Has a branched tracheal system. Respiration is done by air ducts. Free circulatory system exists. Excretion is accomplished by the Malpighian duct