Why are the tentacles on a hydra the most sensitive?

The tentacles of a hydra are the most sensitive because they are equipped with specialized cells called cnidocytes, which contain stinging structures called nematocysts. These cells allow the hydra to detect and capture prey, as well as sense changes in its environment. The high concentration of nerve cells in the tentacles enhances their sensitivity, enabling the hydra to respond quickly to stimuli. This adaptation is crucial for both feeding and defense.