Movement patterns and photosensitivity of Trichonema spp. infective larvae in non-directional light

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Abstract
1. Trichonema spp. infective larvae once stimulated move in darkness, dim and bright visible light and ultra-violet light. There was no significant difference between the distances moved in these photic conditions.2. Movement patterns were variable but certain shapes of tracks, rates of reversal and reversing types were typical of certain light conditions.3. The rate of reversing was dependent on light conditions and was random in direction.4. Sensory adaptation was suggested in visible light, but not in ultra-violet at 366 μm.5. Movement analyses in flashing light suggested that pulsating stimuli at intervals of 100 ms or less were required for sensory input approximating to physiologically continuous stimulation.6. Larvae showed an idiosyncrasy in their tracks, repeated tracking with the same individual giving less varied tracks than with different larvae.The author is indebted to Mr J. M. Smith for his painstaking efforts in preparing the tracks and his willing and skilful assistance throughout.