Arthropod

Arthropod, largest and most diverse phylum of the animal kingdom, containing insects, millipedes, centipedes, crustacea, arachnida, and king crabs. Arthropods are characterized by a segmented exoskeleton (external skeleton) with joined limbs that is shed at intervals, the animal emerging in a new, soft exoskeleton that has developed beneath; often this molting is followed by rapid growth. Molting may cease on attainment of adulthood, but many crustacea molt periodically throughout their lives.