1. Hydrostatic skeleton
• In organisms with hydrostatic skeletons,
– the muscles contract to change the shape of
the coelom, which then produces movement due
to the pressure of the fluid inside the fluid-filled
cavity.
– Organs in coelom support by aqueous fluid
– Resist to external compression
– Sea anemones, earthworms, Cnidarian etc.
– Contraction of muscle change the shape of
coelom, the pressure of fluid produce movement