Foraminifers (commonly called "forams") are the largest members of the group of single-celled microbes known as Protists. These tiny creatures make up the most diverse group of marine organisms known, with more than 60,000 extinct and extant species recognized today. They can be found in oceans worldwide, living either on or buried below the sea floor or as free-floating plankton at the water’s surface. The amoeboid cell of a foram contains a hard, internal shell or test that is divided into chambers. The test can either be excreted by the organism, in which case it will be calcitic or aragonitic in nature, or it can be assembled from a mixture of organic glue and sand or other small particles (agglutinated). Traditionally, species have been classified by the morphology of their tests, with groups characterized by test material and internal chamber arrangement. Most species have porous tests (hence foramina, or windows), from which the cell’s cytoplasm can be extruded in long arms called rhizopodia. These pseudopodia aid both in movement and capturing food such as diatoms and detritus. Interestingly, some large, benthic species are known to harbor symbiotic algae in the chambers of their tests, which provide the extra nutrients needed by these foraminifera in order to grow to such a large size.

This particular species, Cycloclypeus carpenteri, is a very large, benthic foraminifer that is placed in the family Nummulitidae. It can be found in high abundance in the tropical waters of the Indo-Pacific and Western-Pacific Oceans. Larger species of foraminifera (2mm-13mm) in general prefer shallow, nutrient depleted waters with a high level of visibility, an environment associated with coral reefs. The flat, discus-like shape of the specimen pictured above is not an uncommon morphology for benthic forams such as C. carpenteri. Note the clearly visible chambers in the cutaway movies. When the foram was alive, these chambers would have housed symbiotic algae, providing the organism with extra nutrients conducive to its rapid growth.

Other forams on DigiMorph: Calcarina

This macrospheric specimen was collected from Guam. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Sue Richardson of the Smithsonian Marine Station at Fort Pierce. Funding for scanning was provided by an National Science Foundation Digital Libraries Initiative grant to Dr. Tim Rowe.

This specimen was scanned by Matthew Colbert on 11 August 2004 along the coronal axis for a total of 133 1024x1024 pixel slices. Each slice is 0.0121 mm thick, with an interslice spacing of 0.0121 mm and a field of reconstruction of 11.35 mm.

Literature

Prothero, Donald R. 2004. Bringing Fossils To Life: An Introduction To Paleobiology: 2nd Edition. McGraw-Hill Science/Engineering/Math, Boston, 503 pp.

Links

Introduction to Foraminifera (Univ. of California, Berkeley).

None available.