''Sticholonche'' is a genus of

radiolaria The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ectoplasm. The el ...

ns with a single species, ''Sticholonche zanclea'', found in open

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...

s at depths of 99–510 metres. It is generally considered a

heliozoa Heliozoa, commonly known as sun-animalcules, are microbial eukaryotes ( protists) with stiff arms (axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule-supported projections fr ...

n, placed in its own order, called the Taxopodida. However it has also been classified as an unusual radiolarian, and this has gained support from genetic studies, which place it near the Acantharea. ''Sticholonche'' are usually around 200

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...

, though this varies considerably, and have a bilaterally symmetric shape, somewhat flattened and widened at the front. The

axopod A pseudopod or pseudopodium (plural: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filament ...

s are arranged into distinct rows, six of which lie in a dorsal groove and are rigid, and the rest of which are mobile. These are used primarily for buoyancy, rather than feeding. They also have fourteen groups of prominent spines, and many smaller spicules, although there is no central capsule as in true radiolarians.

References

Further reading