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Description of  Biostratigraphic and Geological Significance of Planktonic Foraminifera

Foraminifera are marine, free-living, amoeboid protozoa (in Greek, proto = first and zoa = animals). They are single-celled eukaryotes (organisms the cytoplasm of which is organized into a complex structure with internal membranes and contains a nucleus, mitochondria, chloroplasts, and Golgi bodies, see Fig. 1.1), and they exhibit animal-like (cf. plant-like) behaviour. Usually, they secrete an elaborate, solid carbonate skeleton (or test) that contains the bulk of the cell, but some forms accrete and cement tests made of sedimentary particles. The foraminiferal test is divided into a series of chambers, which increase in number during growth. In life, they exhibit extra-skeletal pseudopodia (temporary organic projections) and web-like filaments that can be granular, branched and fused (rhizopodia), or pencil-shaped and pointed (filopodia). The pseudopodia emerge from the cell body (see Plate 1.1 below) and enable bidirectional cytoplasmic flow that transports nutrients to the body of the cell (Baldauf, 2008).