They function in protecting the animal and helping capture its food. These 2 layers are separated by a jelly-like layer called the mesoglea. Within the mesoglea we find a nerve net. There is no brain. They contain a central cavity called the Gastrovascular cavity.
Digestion takes place here and the contents are absorbed by the endodermal cells.
The undigested food is expelled through its mouth. They contain radial symmetry. Some organisms are sessile while others are free floating. They reproduce by budding and regeneration. They also reproduce sexually.