Question

Why hydra has both type of digestion ?

Answer 1

Enzymes secreted by the hydra , it will down food from absorption. Hydra also use extracellular digestion and secrete molecules to break down the substrate they will grow. And intracellular digestion take place inside the cell. That's why hydra has two types of digestion....
i hope it may help you

Answer 2

Hydra have nutritive cells which are present at the lining of Gastrovascular cavity.
The cells perform intercellular digestion inside itself and also secrete enzymes outside(in the gastrovascular cavity) and there the enzymes also digest food which is extra cellular(out of the cell but in the cavity).
So it have both extra and intracellular digestion.