Frog legs dancing after being Salted. The detached frog legs start to twitch with just a pinch of salt. It happens because despite the animal being dead, the legs still contain some living cells that can respond to stimuli. Sodium ions present in the applied salt behave like signals from the brain and cause the nerves to fire. Since there is still a source of energy left in the cells, the muscles contract in response to the signal and thus the legs “dance.”