Foraminifera are found in all marine environments, they may be planktic or benthic in mode of life. The name foraminiferida is derived from the foramen, the connecting hole through the wall (septa) between each chamber. Foraminifera have a geological range from the earliest Cambrian to the present day. They are primarily classified by the composition and morphology of the test. Three basic wall compositions are recognized—organic, agglutinated, and secreted calcium carbonate (or more rarely silica).

Based on the generally accepted classification of foraminifera from Loeblich and Tappan (1964), the Order Foraminiferida belongs to the Kingdom Protista, Subkingdom Protozoa, Phylum Sarcomastigophora, Subphylum Sarcodina, Superclass Rhizopoda, Class Granuloreticulosea. Breaking down this nomenclature tells us that foraminifera are testate (meaning they have a shell), protozoa (single-celled organism characterized by the absence of tissue and organs), which possess granuloreticulose pseudopodia (thread-like extensions of the ectoplasm often including grains or tiny particles of various materials).

Herodotus, fifth century BC, noted that the limestone of the Egyptian pyramids contained large benthic foraminifer Nummulites. The famous 1872 HMS Challenger cruise was the first scientific oceanographic research expedition to sample the ocean floor—it collected so many samples that several scientists were working on the material well into the 1880’s. Workers such as Cushman in the US and Subbotina in the USSR developed the use of foraminifera as biostratigraphic tools. Of the approximately 4000 living species of foraminifera, the life cycles of only 20 or so are known.

references:

1: Karen Wetmore, “FORAM FACTS – AN INTRODUCTION TO FORAMINIFERA.” Learning From The Fossil Record, The University of California Museum of Paleontology

2: ”Foraminifera,” MIRACLE, Microfossil Image Recovery And Circulation for Learning and Education, University College London Micropalaeontology Unit.