DIGESTION IN HYDRA SYSTEM

INGESTION

 

Hydra has a simple digestive cavity called coelenteron which has only one opening that serves both as mouth and anus. It feeds on small aquatic animals like crustaceans. When a prey comes in contact with its tentacles, the nematocysts or stinging cells immediately discharge and paralyze the prey. In the mean the time, tissue fluids are released from the prey which cause contraction of the tentacles and opening of the mouth. The tentacles holding the captured animals shorten and bend over the mouth. Which opens widely and engulf the prey. The food is then pushed into the digestive cavity. 

 

DIGESTION

In hydra both extra and intracellular digestion takes place. When food (prey) is inside the digestive cavity, enzymes are secreted from the endodermal cells lining the cavity. The enzymes cause the extra cellular digestion. As the prey breaks down into smaller pieces, some of the pieces are taken up by the cells lining the cavity and food vacuoles are formed. Enzymes within the cell change non- diffusible nutrients into diffusible ones by intracellular digestion. The products of digestion formed in he digestive cavity are also absorbed by the endodermal cells and then may be diffused into the ectodermal cells.

 

EGESTION

The undigested food particles are brought up to the mouth and removed. Therefore mouth also functions as the anus.