Fig. 6. Swimming speeds of the intact larvae (A), larvae that had recovered from anesthetia (B), anterior- (C) and posterior- (D) pigment cell-ablated larvae in response to repeated stimuli consisting of the onset (6 s light period) and cessation (1.5 s dark period) of light (494 nm; 5.0x10^-3 J m^-2 s^-1). Intact larvae (A) started swimming when the light was switched off, and slowed swimming speed when the light was switched on. Pre-anesthetized (B) and the anterior pigment cell-ablated larvae (C) showed the same photoresponse as intact larvae. Posterior pigment cell-ablated larvae (D) showed no photoresponse whether the light was switched on or off.