hydroskeleton
Hydroskeleton are type of skeletal structures for some organisms which consisted of a fuild-filled cavity for support and framework.
Exoskeleton
1. Hard part that lies outside of the body
2. Develops from ectoderm
3. Composed mainly of hard non-living material called chitin.
Endoskeleton
1. Hard part that lies inside the body
2. Develops from endoderm
3. Composed of living material i.e. bone tissue
