The pharyngeal nervous system orchestrates feeding behavior in planarians

Area of Science:

• * Zoology
• * Neurobiology
• * Animal Behavior

Background:

• * Planarians display cephalization but possess a unique feeding mechanism involving a retractable, trunk-positioned pharynx.
• * The control of complex, goal-directed feeding movements in planarians remains poorly understood.
• * Understanding planarian feeding behavior offers insights into bilaterian evolution and nervous system function.

Purpose of the Study:

• * To investigate the neural control mechanisms underlying planarian feeding behavior.
• * To determine the role of the pharyngeal nervous system (PhNS) in coordinating feeding movements.
• * To elucidate the communication between the PhNS and the brain in guiding feeding actions.

Main Methods:

• * Utilized the freshwater planarian *Dugesia japonica* for experimental studies.
• * Isolated the pharynx to assess its intrinsic feeding capabilities.
• * Employed gene-specific silencing via RNA interference (RNAi) to study gene functions.

Main Results:

• * An isolated planarian pharynx autonomously executes the full sequence of feeding functions, including sensing, approach, and ingestion.
• * The pharyngeal nervous system (PhNS) is essential for the pharynx's intrinsic feeding capabilities.
• * Silencing PhNS components impaired both pharyngeal feeding and whole-animal food-localization movements, suggesting brain communication.

Conclusions:

• * The PhNS plays a central and unexpected role in orchestrating planarian feeding behavior.
• * The PhNS is critical for linking unique morphological traits to functional feeding actions in planarians.
• * These findings highlight the PhNS as a key neural substrate for complex feeding in planarians, with implications for brain-body coordination.