Predation behaviour of land planarians

Abstract

Predatory behaviour of land planarians is seldom observed or reported. Aspects reported are (1) finding prey; (2) attack behaviour; (3) capture using adhesive mucus, pharyngeal action, poisonous secretions, physical embrace; (4) feeding by extension of pharynx, releasing copious digestive fluid. The species Bipalium kewense, B. adventitium and B. pennsylvanicum attack earthworms, immobilizing them by physical holding, digesting by pharyngeal secretions and then ingesting the treated tissue. Group attacks on giant African land snails involving chemotactic tracking, occur in Platydemus manokwari and Endeavouria septemlineata. Specialized capture methods are used by some species; Rhynchodemus sylvaticus uses an expanded cephalic hood to capture small insects and in Africa, termites are captured by the elongated anterior of Microplana termitophaga as planarians wait within the colony air shaft openings to ensnare the workers in sticky mucus. The result of extensive predation by land planarians may seriously reduce the prey, e.g., providing effective population control of giant land snails by introduced Platydemus manokwari, or causing serious depletion of desirable earthworm populations by the exotic Artioposthia triangulata in North Ireland.Key wordsland planarianspredationcapture methodsadhesive mucuspopulation control and depletion