Video for Skeletal System - Structure, Support and Protection Center
A group of animals called Arthropods (insects, spiders and crabs) have skeletons on the outside of their body. This structure is called an exoskeleton. The exoskeleton completely covers the outside of the body and the muscles inside stick to it. Exoskeletons are hard and protect the body. Because the exoskeleton is hard and rigid, an animal with an exoskeleton cannot grow unless it sheds its old exoskeleton and secretes a new one. This process is called molting. Let's watch a Spider Crab molt its shell.
