How does the stinging cell of a hydra work?

Hydra has several types of stinging cells. Most of them are located on the tentacles, where they are located with batteries. Inside the stinging cells there are capsules with poison and spirally coiled filaments. Outside there are sensitive hairs that react to external stimuli. If the victim touches the hairs, then a coiled hollow thread and a poisonous liquid are thrown out of the cell. In some cells, the threads stick to the victim, in others, they inject poison inside. Used stinging cells are replaced over time.