Locomotion and feeding of Acanthamoeba at the water-air interface of ponds.

Acanthamoeba trophozoites attach to and effect amoeboid locomotion at the water-air interface of ponds. Their locomotory rate (approximately 0.8 microm s(-1)) and manner of independent movement at this interface is similar to that over solid substrata. Adhesion forces developed between amoebae and the water-air interface are greater than gravity and thus amoebae are also transported passively without detachment. Amoebae docked with the water-air interface remain and flourish here as they are shown, by using green fluorescent protein-labelled Aeromonas hydrophila, to feed on bacteria that occur at the interface, digesting them intracellularly.