The carnivorous genus Byblis is usually described as a passive flypaper trap. But our examinations show that the tentacles move on contact with prey. Different than in Drosera, where the tentacle bending is the result of a certain hydraulically expansed cell region, the movement of Byblis tentacles looks quite primitive; however, very effectiv.
When touched by prey, the liquid flow inside the tentacle stalk changes from permanent flow (to provide the glue drop on its head) to pulsed flow, which creates constrictions between the liquid phases. Due to gravity, the tentacles in contact with prey collapse at these constrictions and the prey descends to the leaf surface, where the digestion takes place.
Interestingly, the hydraulic action continues even after the collapse to soak the prey, but the constrictions avoid that the hydraulically still active tentacles errect again.
This video is an excerpt from a new developing film on the tentacle movement of sticky Australian plants. Also in our focus : Lindernia cleistandra, coming soon ...