Sixth Grade
Worksheets
Arthropods
Insects, spiders, crabs, and scorpions belong to the phylum Arthropoda. Arthropods are invertebrate animals without a backbone. They have segmented bodies and an exoskeleton, a skeleton outside of their bodies. The name comes from another feature they share - jointed appendages, such as wings, legs, and mouthparts. In Greek, arthro means "joint," and pod means "foot" or "leg."
All arthropods have an external skeleton - an exoskeleton. Some exoskeletons are hard, like that of a lobster. It is made out of chitin. Some exoskeletons are leathery, like that of a caterpillar. Both types are waterproof. The exoskeleton keeps the animal from drying out. This characteristic gave arthropods the ability to live on land.
As arthropods grow larger, they shed their exoskeletons and grow new, bigger ones. This process is called molting. After an arthropod has molted, its new skeleton is soft for a while. It is not as well-protected until the new exoskeleton hardens.
