Why is a battery-operated light with a red filter useful for observing shrimp?

Shrimp are less disturbed by red light than by bright white light, allowing for less intrusive viewing.

Dedicated observers looking to watch shrimp activity after the main lights are turned off often employ specific lighting techniques to avoid startling the crustaceans. The text indicates that using a small, battery-operated light equipped with a red filter is a useful technique for this purpose. The rationale behind this choice is that shrimp react less negatively to the color red compared to intense, bright white light. By using this specific wavelength, the observer can maintain a better vantage point to witness the natural nighttime movements without significantly disrupting the shrimp's behavior due to excessive visual stimulation or perceived threat.