Foraminifera Stercomata are produced by members of several different subclades of Foraminifera that possess organic-walled or agglutinated tests, including: single-chambered taxa with spherical organic-walled tests (e.g.,
Bathyallogromia and other undescribed species), single-chambered taxa with sac-like agglutinated tests (e.g.,
Saccammina and
Leptammina), single-chambered taxa with tubular agglutinated tests (e.g.,
Bathysiphon), multi-chambered taxa with organic-walled tests (e.g.,
Nodellum and
Resigella), taxa with complex agglutinated tests composed of delicate branching tubes (Komokioidea), and deep-sea taxa with large, complex tests agglutinated tests (Xenophyophorea). which is a key morphological feature. Saccamminid tests are often globular, ovoid, or flask-shaped, though some can take more complex, branching shapes. These generally simple shapes are helpful in the bathyal and abyssal sediments in which Saccamminids are abundant and genetically diverse. At abyssal depths, organic carbon flux is tiny, so every gram of biomass is essential. A single-chambered test costs less energy to build and maintain and requires less
biomineralization or sediment manipulation to agglutinate than a multi-chambered test does. Saccamminids are therefore uniquely prevalent in low-food, low-oxygen environments where other calcareous foraminifera can be rare.
Komokiaceans Xenophyophores In xenophyophores, the stercomata are contained within an organic tubes called stercomare.
Multichambered, organic-walled foraminiferans Gromiida Gromiida is a subclade of
Endomyxa, a clade that branches within the more inclusive group
Rhizaria, a clade that encompasses a diverse array free-living and parasitic single-celled
eukaryotes that possess branching or anastomosing
pseudopodia and complex life cycles. In
Gromia, the only described genus of Gromiida, stercomata are spherical to ovoid in shape and range in color from brown to gray to orange. Individual stercomes range in size from <5 μm (
G. psammophila) to 15-30 μm (
G. saoirsei). Unlike the stercomata in foraminiferans, the stercomata in gromiids are retained in the cytoplasm and not stored outside of the cell body; however, after the release of flagellated gametes during sexual reproduction, the stercomata remain in the interior of the test.
Testate Amoebae ==See also==