High degree of independence in the feeding apparatus of planarian flatworms

In this contribution, feeding behaviour assays with the three species Paucumara falcata, Dugesia sp. and Girardia sp. were used to investigate the function of the pharynx during feeding and whether absence of feeding behaviour until full regeneration is a widespread phenomenon among planarians from different taxonomic groups. Our results showed that feeding behaviour of decapitated flatworms was inhibited. Intact worms responded only to pork liver pieces, but isolated pharynges were highly responsive to both pork liver pieces and pork liver extracts. After transverse cutting, the oral part of the isolated pharynx was responsive, while the aboral part showed no response to food items, suggesting that the oral portion of pharynx plays a crucial role during feeding.