Painless mutant larvae displayed normal navigational pattern in response to gentle touch. (A) Nociceptive behaviors of wild-type and pain mutants in response to noxious mechanical stimuli (50 mN) were examined. Response frequency (i.e. the percentage of larvae that showed complete rolling-over behaviors) of larvae was examined (three trials). Number of larvae tested: w-1118, n=83; pain1, n=74; pain3, n=91. *p < 0.05, ***p<0.005, t-test. (B) Navigational pattern of pain mutant larvae in response to tactile stimuli was examined. Number of larvae tested: w-1118, n=21; pain1, n=26; pain3, n=26. p>0.1 for t-test and one-way ANOVA test. Error bars represent SEM.