The exoskeleton of arthropods is made up of a complex homo polysaccharide called 

Chitin is a homopolyme rmade of N -acetyl glucoseamine.

 They have as building blocks, amino-sugars and chemically modified sugars (e.g., glucosamine, N-acetyl galactosamine, etc.). Exoskeletons of arthropods, have a complex polysaccharide called chitin. These complex polysaccharides are mostly homopolymers.