The ultrastructure of a planktonic foraminifer, Globigerinoides sacculifer (Brady), and its symbiotic dinoflagellates

Abstract

Surfacedwelling Globigerinoides sacculifer (Brady ) , collected in the Gulf Stream off Bimini, Bahamas, possesses dinoflagellate symbionts, which exhibit a diurnal migratory cycle of ingress into the test chambers in the evening and egress to the distal parts of the ectoplasm along the spines in the morning. The ultrastructure of the symbionts and host was examined in a spatial sequence proceeding from the perimeter of the ectoplasm to the endoplasm of progressively smaller chambers (hence, of progressively increasing age). The peripheral ectoplasm forms a fine network of rhizopodia embracing the symbionts. Near the aperture, the ectoplasm coalesces and encloses the symbionts, which are carried into and distributed within the endoplasm of the final chamber. Large numbers of symbionts were observed in all but the smallest chambers.

The ecology of colonial radiolarians : their colony morphology, trophic interactions and associations, behavior, distribution, and the photosynthesis of their symbionts

“…They appear to be most common in oligotrophic regions, such as the Mediterranean and Sargasso Seas Haeckel, 1887;Anderson, 1976; our own observations). Al though considerable research was done on this group in the latter part of the nineteenth century, they have received relatively 1 i ttle attention until recently.…”

“…All those species examined (and I believe most other species as well) responded to light by moving their symbiotic algae. The same behavior occurs in the foraminiferan Giobigerinoides saccuiifer which moves its algae into its test at night and out during the day (Anderson and Bé, 1976). There may be functional significance to both of these types of behavior.…”

Biomineralization in perforate foraminifera

“…Some have suggested that dissolved organic matter may be taken up through the pores in the benthic Patellina (Berthold, 1976). In G. sacculifer, pseudopodia appear to penetrate through the pore plates (Anderson and Bé, 1976). Pores in the benthic species Patellina corrugata have been reported to exist from the beginning of chamber formation (Berthold, 1976) and pores are observed in the O. universa sphere once initial calcification has locked in the spherical morphology of the chamber (Spero, 1988).…”

Acquired phototrophy in aquatic protists

“…day versus night to optimize photosynthesis) and abundances (e.g. partial digestion for energy purposes such as gametogenesis) (Anderson & Bé 1976, Anderson 1983a.…”