1. Defense: Nematocysts contain a poisonous substance called hypnotoxin. Hydra defends itself with this toxic substance.
2. Prey capture: Hydra captures food by means of nematocysts. Then paralyze the victim. Dr. Siddiq Publications
3. Movement: Nematocyst cells help the hydra to move. Different types of movements occur in hydra. Dr. Siddiq Publications
4. Clogging the body: Nematocysts secrete sticky substances. By this, the hydra is stuck to an object. Dr. Siddiq Publications