Deposit feeding in selected deep-sea and shallow-water benthic foraminifera

Ultrastructural evidence for deposit feeding in two deep-sea foraminifera, Globobulimina pacifica and Uvigerina peregrina, is presented and compared with results on Ammonia beccarii, a common nearshore dweller. In all three taxa, food vacuoles are common in the last chamber and contain numerous aggregates of sediment and organic detritus. Within aggregates, bacteria are often found surrounded by a sheath of sediment particles generally bound by bacterial exopolymers. In actively-feeding individuals of A. beccarii, food vacuoles along the distal edge of the cytoplast contain live bacteria associated with sediment aggregates as well. Bacteria do not occur in the cell's interior, although hollow sheaths of sediment and detritus do persist. This indicates that the digestion of bacteria may occur very near the distal margin of the cytoplast in this species. Likewise, sediment aggregates both with and without bacteria occur in food vacuoles of the deep-sea species examined. All three species ingest relatively large volumes of organic detritus associated with sediments, although the role of this material in the diet of foraminifera is uncertain. These results suggest that the deep-sea and shallow-water species examined feed on bacteria by deposit feeding and ingest bacterial cells, in addition to relatively large volumes of associated sediment and organic detritus. © 1994.

Duke Scholars

Author Bruce Corliss Earth and Climate Sciences