Visual Rhythms in Stomatopod Crustaceans Observed in the Pseudopupil

Area of Science:

• Animal physiology
• Chronobiology
• Crustacean vision

Background:

• Endogenous rhythms significantly impact animal visual functions.
• Circadian processes are crucial for adapting sensory systems to environmental cycles.

Purpose of the Study:

• To investigate visual rhythms in two stomatopod crustacean species: Squilla empusa (nocturnal/diurnal) and Gonodactylus oerstedii (diurnal).
• To understand how circadian rhythms affect visual function, specifically pupillary responses, in different light conditions.

Main Methods:

• Intracellular optical physiology techniques were employed.
• Reflectance from the deep pseudopupil of compound eyes was monitored.
• Experiments were conducted under constant conditions for up to two weeks.

Main Results:

• Both Squilla empusa and Gonodactylus oerstedii displayed circadian rhythms in visual function.
• Squilla empusa showed a stronger pupillary response during subjective night, with increased pupillary reflectance during subjective day.
• Rhythms in Gonodactylus oerstedii were of lower amplitude and harder to detect.

Conclusions:

• Circadian rhythms play a vital role in optimizing nocturnal vision for sensitivity and dynamic range in arthropods.
• Species-specific differences in visual rhythms may reflect adaptations to different activity patterns.
• Endogenous rhythms are fundamental to the adaptive strategies of visual systems in crustaceans.