Editing Phaeodarea (section)

== Characteristics ==

=== Cell structure ===

Phaeodarea are [[unicellular]] [[protists]] that grow a capsule with a thick, double-layered [[cell wall|wall]] containing two kinds of pores or openings: the large type, known as "'''astropylum'''" or oral pore, from which a massive strand of [[cytoplasm]] protrudes; and the smaller type, known as "'''parapylae'''" or lateral pores, from which thinner strands of cytoplasm protrude. External to the capsule there is a large, often darkly pigmented, mass of [[granule (cell biology)|granular]] cytoplasm called "'''phaeodium'''" which contains undigested or partially digested food or debris. Their [[crista|mitochondrial cristae]] are tubular.<ref name="Adl 2019"/><ref name="HP Radiolaria and Phaeodaria"/>

Most Phaeodaria have a [[Protist shell#Silicon-based shells|siliceous skeleton]] composed of amorphous [[silica]] joined by [[organic matter]]. They may contain more organic matter than [[Polycystinea]] ([[Radiolaria]]). Skeletons of some species are composed of hollow bars, instead of solid rods as in Polycystinea. Others have ornate spicules scattered through the external cytoplasm in a variety of forms, including geodesic frameworks, spheres or polyhedra. Other species have porous [[protist shell|shells]] that are either bivalved, resembling clams, or vase-like with ornamentations around the opening. Other species have highly branched antler-llike spines stemming from a central shell. Unlike Polycystinea, the capsular wall surrounding the denser [[endoplasm]] of Phaeodarea lacks fusules.<ref name="Adl 2019"/><ref name="HP Radiolaria and Phaeodaria"/>

Their cell size ranges from hundreds of [[micrometre]]s to a few [[millimetre]]s, roughly depending on the [[family (biology)|family]]. For example, species of [[Tuscaroridae]] exceed 3 mm, while [[Challengeriidae]] are generally smaller than a few hundred μm. Some phaeodarians with spherical skeletons are similar to Polycystinea and [[Acantharea]] (Radiolaria), although they are more porous and fragile. Some species of the family Challengeriidae resemble marine [[dinoflagellate]]s, but can be correctly distinguished by the presence of a phaeodium and absence of grooves.<ref name="MPDD Phaeodaria"/>

=== Nutrition ===

The continuous, massive strand of cytoplasm in the astropyle of Phaeodarea provides a pathway to carry digested prey matter into the [[endoplasm]], similarly to some [[testate amoebae]]  and [[foraminifera]]. Among the limited evidence of phaeodarian [[predation]], it was reported in 1986 that a [[mesopelagic]] phaeodarian had absorbed micro[[flagellate]] and [[metazoan]] prey.<ref>{{cite journal|vauthors=Swanberg N, Bennett P, Lindsey JL, Anderson OR|title=The biology of a coelodendrid: a mesopelagic phaeodarian radiolarian|journal=Deep Sea Research Part A. Oceanographic Research Papers|volume=33|issue=1|date=1986|pages=15–25|doi=10.1016/0198-0149(86)90105-6}}</ref> When introduced in the laboratory cultures, [[copepods]] and [[salps]] also were snared by phaeodaria.<ref name="HP Radiolaria and Phaeodaria"/>

=== Reproduction ===

Sexual reproduction of Phaeodaria has not been confirmed, but the release of motile swarmers that are likely [[gamete]]s is widely documented. In the species ''[[Coelodendrum ramosissimum]]'', [[biological dispersal|dispersal]] starts with the disappearance of the phaeodium, followed by the dissolution of the capsule and the creation of small plasmodial spheres in the [[Ectoplasm (cell biology)|ectoplasm]]; each of the spheres produces hundreds of [[multinucleate]]d amoebae that eventually form swarmers with two [[undulipodia]] ([[flagella]]).<ref name="HP Radiolaria and Phaeodaria"/>