Quiz 18: Smaller Ecdysozoans
A cuticle is a non-living external layer which is secreted by the epidermis. A firm cuticle surrounding the body wall, like that present in roundworms and arthropods restricts the growth of the organism.
As the cuticle of animals does not grow along with the animal it is shed and a new larger cuticle is formed. This process is known as ecdysis.
The fluid-filled pseudocoel along with the surrounding muscles constitutes a hydrostatic skeleton. The pressure of the fluid in the coelom along with the action of the surrounding muscles helps animals in burrowing and to produce a change in the shape of the organism.