Julie K Lundgren 
Skeletons and Exoskeletons [PDF ebook] 

This book explains how humans and animals have skeletons to support the inner workings of their bodies. Students learn about the differences between endoskeletons and exoskeletons, as well as view examples of animals that have one type of skeleton or the other. Detailed information on these animals includes their habitats, eating habits, and ways they adapt to survive. A special section called "Explore Your World" outlines an experiment for examining this topic firsthand.