Crayfish-Tracking Motion Vision to analyze the locomotor activity induced by changes in environmental lighting

Abstract

Crayfish show locomotor activity modulated by environmental lighting. Yet, little is known about different light spectra stimulation effects on the locomotor activity of crayfish, and laboratory instruments are generally limited to the study of a single animal. As such, this research describes the development and implementation of the Crayfish-Tracking Motion Vision (CTMV) system. Based on artificial vision, this system allowed for the observation and recording of locomotor activity in one to four Procambarus clarkii crayfish that were placed in individual compartments. The effect of blue or green monochromatic light stimulation was explored in two groups of dark-adapted crayfish (with a total of 15 adult crayfish). Light-emitting-diodes of blue or green spectra were applied for 5 min while locomotor activity in crayfish was monitored in a large container. Both light pulses caused similar reaction times of locomotor activity (2.9 ± 3.5 s). Meanwhile, the displacement score of “blue light” animals (2.1 ± 0.9 m) was lower than that of “green light” animals (2.8 ± 0.6 m). In contrast, velocity (1.1 ± 1 cm/s) and acceleration data (0 ± 0.8 cm/s²) of the two groups were similar. Finally, the locomotor activity decreased significantly when container size was decreased. These results showed that the CTMV system is appropriate for measuring the locomotor activities of multiple crayfish and suggested that both monochromatic lights induced different locomotor behavior in the crayfish. It has been postulated that this light-induced reflex activity, is caused by an interplay of the photoreceptor system output with a circadian system modulating light sensitivity and locomotor behavior in the crayfish,. It can be inferred that the CTMV system will benefit subsequent studies focused on light-induced reflex activity in crustaceans.