Answer:
Gastrovascular Cavity
Explanation:
Hydra is commonly found in freshwater ponds and ditches as solitary organisms, in underside of aquatic leaves and lily pads in cool,clean freshwater pools and streams. It has a *Cylindrical body shape*.
Hydra possesses an internal body cavity, the *Gastrovascular cavity *,lined by gastrodermis and has a single opening,the mouth,which serves as an anus.
The Gastrovascular cavity of Hydra is a site for *digestion and nutrient distribution*,and also serves as anus.
