Exoskeleton is the external supporting and protective hard
Different Types of Exoskeleton are:
Example: Scales of reptiles except, crocodile and tortoise, horns, hoofs,
beak, claws, feathers, hairs, nails, etc.
Example: Scales of fishes, scales of amphibia,
scales of crocodile and tortoise.
Exoskeleton of Invertebrates:
Example: Spines, shell, corals, cuticle, etc.
Hydroskeleton is made up of fluid
Example: In earthworm and ascaris.
Endoskeleton of Vertebrates: It is the internal
supporting and protective hard structure.
Total 206 bones are found in a human body.
Study of bone is called osteology.
Bones are of 3 types:
Membrane or dermal bones
The bones in human being form 20% of the total body weight.