Introduction to Animal Skeleton

The Skeleton is tough and rigid framework of the body of animals which provides protection, shape, support to the body organs. It is composed of inorganic or organic substance or both. 

There are three main types of skeleton in animals. 
1) Hydrostatic Skeleton
2) Exoskeleton
3) Endoskeleton

Hydrostatic skeletons: 

Hydrostatic skeletons are found in soft-bodied in vertebrates like sea anemones, worms and jellyfish. Such animals have a fluid-filled cavity called a coelom which is surrounded by muscle wall. The pressure of the fluid pressing against the muscle wall provides the animal with rigidity which acts as a skeleton. The hydrostatic skeleton gives the animal structural integrity and allows limited mobility. 

Exoskeletons:

The exoskeleton is that type of skeleton which lies outside the soft parts of the body insects like all arthropods have an exoskeleton comprised of rigid plates that provide protection and support, however, it is jointed so that it does not restrict the movements and mobility of the animal. In insects, the exoskeleton is made up of a hard slightly flexible carbohydrate called chitin. Crustaceans like lobsters and crabs have an exoskeleton - its exoskeleton is divided into several distinct sections making mobility a little easier. The exoskeleton is made mainly from chitin and crystalline substances such as calcium carbonate. This makes the plates that make up their exoskeletons very hard and rigid. In order to grow, arthropods have to shed their whole exoskeleton at once. A new exoskeleton is produced beneath the old one. The process of shedding the old exoskeleton is called molting.


Endoskeletons:

The third kind of skeleton is the endoskeleton. It is a bone or cartilage based skeleton that exists wholly inside of an animal's body. All vertebrates including humans have endoskeletons. The endoskeleton gives shape and support to the body and has bones that meet at joints muscles attach to the bones provide a means of movement and mobility.
A skeleton also protects a body's soft organs and provides attachment sites for muscles.