On the Food Selectivity of Oysters

Abstract

Discrimination be-tween different spp. of suspended participate matter in feeding is demonstrated in Ostrea virginica. When a culture of purple sulfur bacteria, Chromatium perty, is added to the water in the oyster culture trays, the pseudofeces are pink or purple due to the high content of rejected purple bacteria, while the material that passes through the digestive tract is greenish or brown. The rejection of purple forms takes place most effectively during the first few days after they are added to the water; later some of the oysters ingest purple forms without discrimination and feces then take on a reddish cast.