The pharyngeal nervous system orchestrates feeding behavior in planarians

• Published in: Science advances Vol. 6; no. 15; p. eaaz0882
• Main Authors: Miyamoto, Mai, Hattori, Miki, Hosoda, Kazutaka, Sawamoto, Mika, Motoishi, Minako, Hayashi, Tetsutaro, Inoue, Takeshi, Umesono, Yoshihiko
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01.04.2020
• Subjects: Animals; Evolutionary Biology; Feeding Behavior; Models, Biological; Nervous System Physiological Phenomena; Organismal Biology; Pharynx - innervation; Planarians - physiology; SciAdv r-articles; Signal Transduction
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aaz0882

Planarians exhibit traits of cephalization but are unique among bilaterians in that they ingest food by means of goal-directed movements of a trunk-positioned pharynx, following protrusion of the pharynx out of the body, raising the question of how planarians control such a complex set of body movements for achieving robust feeding. Here, we use the freshwater planarian to show that an isolated pharynx amputated from the planarian body self-directedly executes its entire sequence of feeding functions: food sensing, approach, decisions about ingestion, and intake. Gene-specific silencing experiments by RNA interference demonstrated that the pharyngeal nervous system (PhNS) is required not only for feeding functions of the pharynx itself but also for food-localization movements of individual animals, presumably via communication with the brain. These findings reveal an unexpected central role of the PhNS in the linkage between unique morphological phenotypes and feeding behavior in planarians.