Cerebral photoreception in mantis shrimp.

Area of Science:

• Crustacean biology
• Neuroethology
• Sensory neuroscience

Background:

• Stomatopods (mantis shrimps) exhibit unparalleled visual diversity via ocular opsins and filters.
• Extraocular photoreceptors are known in other animals, but their function in crustaceans remains largely uncharacterized.

Purpose of the Study:

• To investigate the presence and function of extraocular photoreceptors in the mantis shrimp Neogonodactylus oerstedii.
• To determine if these photoreceptors contribute to light-sensing behaviors beyond the eyes.

Main Methods:

• Immunohistochemistry to detect opsins and histamine in neural tissues.
• Electrophysiological recordings to measure light-evoked responses from the ventral eye.
• Behavioral observations of intact and blinded mantis shrimp under light stimulation.

Main Results:

• Functional, opsin-based photoreceptors were identified in the anterior central nervous system (cerebral ganglion) and a ventral eye.
• Illumination of these extraocular photoreceptors induced escape-like behaviors, persisting even in blinded individuals.
• Opsins and histamine were localized in the cerebral ganglion and eyestalks, suggesting roles in shelter-seeking and other behaviors.

Conclusions:

• Neogonodactylus oerstedii possesses functional cerebral photoreceptors, adding to their complex light-sensing capabilities.
• Extraocular photoreception likely plays a significant role in mantis shrimp behavior, including predator avoidance and shelter-seeking.
• The discovery highlights novel mechanisms for light detection in arthropods.