BACTERIA FARMING - A POSSIBLE FEEDING STRATEGY OF SOME SMALLER, MOTILE FORAMINIFERA

Some smaller, non-symbiont bearing, epiphytic foraminifera grazing on seagrass leave embankment-like organic traces (Textularia bocki Hoglund, 1947 and Quinqueloculina ungeriana d'Orbigny, 1846). Shape, coloration and texture of the secretion products reveal that the organic material is released over the entire pseudopodial network and suggests that it consists of sulfated glycosaminoglycans. The material secreted by the ephiphytes is a fertile substrate for bacteria and fungi. The dense bacterial and fungal lawns are harvested in turn by the foraminiferal epiphytes. Retracing and what appears to be repeated grazing activity on formerly produced and colonized traces support the theory of a ''farming strategy''. In addition the well-directed movements of the epiphytes towards colonized traces suggests a chemotactic response. The extra energetic cost for mucus production may be balanced by the stimulation of food resources. Secretion patterns and chemotactic reactions are examined.