Figure 11.1 : Steps of Digestion in Amoeba.

Hydra catches the prey with the help of tentacles, a protrusion just outside the mouth. The circumference of mouth can extend according to the size of food particle. Thus it can swallow comparatively large animal. Soon after ingestion, digestion process starts with the help of enzymes secreted by granular glands, which appears just after ingestion. The undigested food is then egested through mouth. The complete mechanism of nutrition in hydra is shown in Figure 11.2.

Figure 11.2 : Steps of Digestion in Hydra.