Explain how having nerve cells clustered around the edge of its bell is advantageous to a medusa

Nerve cells of medusa are specifically organised into a "nerve net" which is a loose network of nerves, located in the epidermis. The nerve net is the simplest form of a nervous system which allows organisms to respond to physical contact. Medusa detects various stimuli including the touch of other animals via this nerve net. Medusa is then capable to respond to its environment, cannot detect the source of the stimulus.

From a high concentration to a low concentration.