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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"/>
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 [[milimetre]]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 ===
=== Nutrition ===
Line 47: Line 49:
== Ecology ==
== Ecology ==


Phaeodaria are exclusively [[marine life|marine]], [[planktonic]] unicellular [[protists]] found in all [[ocean]]s. Very little is known about their role in the [[trophic web]] and about their [[predators]]. [[Dinoflagellate]] [[necrotroph]]s are reported to infect species of Phaeodaria, such as ''[[Syndinium nucleophaga]]''.<ref name="HP Radiolaria and Phaeodaria"/>
Phaeodaria are exclusively [[marine life|marine]], [[holoplanktonic]] unicellular [[protists]] that play an important role in [[marine ecosystem]]s. They are [[heterotrophic]] plankton ([[zooplankton]]) that chiefly live in [[pelagic]] open [[ocean]]s, from the [[surface water|surface]] to the [[deep sea]]. They have not been reported from brackish and high-salinity environments, but they are present in all oceans.<ref name="MPDD Phaeodaria"/>

Very little is known about their role in the [[trophic web]] and about their [[predators]]. [[Dinoflagellate]] [[necrotroph]]s are reported to infect species of Phaeodaria, such as ''[[Syndinium nucleophaga]]''.<ref name="HP Radiolaria and Phaeodaria"/>


==Systematics==
==Systematics==
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<ref name="Adl 2019">{{cite journal|vauthors=Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, Cárdenas P, Čepička I, Chistyakova L, del Campo J, Dunthorn M, Edvardsen B, Eglit Y, Guillou L, Hampl V, Heiss AA, Hoppenrath M, James TY, Karnkowska A, Karpov S, Kim E, Kolisko M, Kudryavtsev A, ((Lahr DJG)), Lara E, Le Gall L, Lynn DH, Mann DG, Massana R, ((Mitchell EAD)), Morrow C, Park JS, Pawlowski JW, Powell MJ, Richter DJ, Rueckert S, Shadwick L, Shimano S, Spiegel FW, Torruella G, Youssef N, Zlatogursky V, Zhang Q|year=2019|title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes|journal=Journal of Eukaryotic Microbiology|volume=66|issue=1 |pages=4–119|doi=10.1111/jeu.12691|pmid=30257078 |pmc=6492006|display-authors=10}}</ref>
<ref name="Adl 2019">{{cite journal|vauthors=Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, Cárdenas P, Čepička I, Chistyakova L, del Campo J, Dunthorn M, Edvardsen B, Eglit Y, Guillou L, Hampl V, Heiss AA, Hoppenrath M, James TY, Karnkowska A, Karpov S, Kim E, Kolisko M, Kudryavtsev A, ((Lahr DJG)), Lara E, Le Gall L, Lynn DH, Mann DG, Massana R, ((Mitchell EAD)), Morrow C, Park JS, Pawlowski JW, Powell MJ, Richter DJ, Rueckert S, Shadwick L, Shimano S, Spiegel FW, Torruella G, Youssef N, Zlatogursky V, Zhang Q|year=2019|title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes|journal=Journal of Eukaryotic Microbiology|volume=66|issue=1 |pages=4–119|doi=10.1111/jeu.12691|pmid=30257078 |pmc=6492006|display-authors=10}}</ref>

<ref name="MPDD Phaeodaria">{{cite book|first1=Yasuhide|last1=Nakamura|first2=Noritoshi|last2=Suzuki|chapter=Chapter 9. Phaeodaria: Diverse Marine Cercozoans of World-Wide Distribution|doi=10.1007/978-4-431-55130-0_9|title=Marine Protists: Diversity and Dymanics|pages=223–249|editor-first1=Susumu|editor-last1=Ohtsuka|editor-first2=Toshinobu|editor-last2=Suzaki|editor-first3=Takeo|editor-last3=Horiguchi|editor-first4=Noritoshi|editor-last4=Suzuki|editor-first5=Fabrice|editor-last5=Not|date=2015|publisher=Springer Japan|isbn=978-4-431-55130-0}}</ref>


}}
}}

Revision as of 08:22, 15 November 2023

Phaeodarea
"Phaeodaria" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Cercozoa
Class: Thecofilosea
Subclass: Phaeodaria
Haeckel 1879
Orders
Diversity
400-500 species[1]
Synonyms[2]

Tripylea Hertwig 1879

Phaeodarea or Phaeodaria is a group of amoeboid cercozoan organisms. They are traditionally considered radiolarians,[3] but in molecular trees do not appear to be close relatives of the other groups, and are instead placed among the Cercozoa.[4] They are distinguished by the structure of their central capsule and by the presence of a phaeodium, an aggregate of waste particles within the cell.

The term "Radiozoa" has been used to refer to radiolaria when Phaeodarea is explicitly excluded.[5]

Phaeodarea produce hollow skeletons composed of amorphous silica and organic material, which rarely fossilize. The endoplasm is divided by a cape with three openings, of which one gives rise to feeding pseudopods, and the others let through bundles of microtubules that support the axopods. Unlike true radiolarians, there are no cross-bridges between them. They also lack symbiotic algae, generally living below the photic zone, and do not produce any strontium sulphate.

Characteristics

Cell structure

Phaeodarea are unicellular protists that grow a capsule with a thick, double-layered 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 granular cytoplasm called "phaeodium" which contains undigested or partially digested food or debris. Their mitochondrial cristae are tubular.[6][1]

Most Phaeodaria have a 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 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.[6][1]

Their cell size ranges from hundreds of micrometres to a few milimetres, roughly depending on the 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 dinoflagellates, but can be correctly distinguished by the presence of a phaeodium and absence of grooves.[7]

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 microflagellate and metazoan prey.[8] When introduced in the laboratory cultures, copepods and salps also were snared by phaeodaria.[1]

Reproduction

Sexual reproduction of Phaeodaria has not been confirmed, but the release of motile swarmers that are likely gametes is widely documented. In the species Coelodendrum ramosissimum, 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; each of the spheres produces hundreds of multinucleated amoebae that eventually form swarmers with two undulipodia (flagella).[1]

Ecology

Phaeodaria are exclusively marine, holoplanktonic unicellular protists that play an important role in marine ecosystems. They are heterotrophic plankton (zooplankton) that chiefly live in pelagic open oceans, from the surface to the deep sea. They have not been reported from brackish and high-salinity environments, but they are present in all oceans.[7]

Very little is known about their role in the trophic web and about their predators. Dinoflagellate necrotrophs are reported to infect species of Phaeodaria, such as Syndinium nucleophaga.[1]

Systematics

Placement

Phaeodaria, along with Polycystinea (Radiolaria) and the freshwater Heliozoa, were previously assigned to the phylum Actinopoda due to their elaborate siliceous skeletons that surround an organic central capsule with pores from which axopodia emerge. However, phylum Actinopoda is polyphyletic and in disuse. Instead, Phaeodaria are now assigned to the class Thecofilosea within the phylum Cercozoa, on the basis of molecular phylogenetics, while the rest of Radiolaria belong to the phylum Retaria. Both Cercozoa and Retaria are part of the eukaryotic supergroup Rhizaria.[1][2] The following cladogram shows the phylogenetic position of all groups of "Actinopoda" (highlighted in bold).[4][6]

Diaphoretickes

Phylogeny

Through phylogenetic analyses it has been discovered that Phaeodarea is a monophyletic clade, but the historical orders and families comprising it aren't. Instead, the clade consists of 11 subclades defined by morphological and phylogenetic values that do not correspond with the traditional orders and families:[9]

clade A

clade B

clade C

clade D

clade E     

clade F

clade G

clade H

clade I

clade J

clade K

Despite this, the current taxonomy by Cavalier-Smith maintains the original classification of suborders[10] divided between two new orders:[11][12]

Modern classification

The modern classification is the following, with the subclass containing a total of 2 orders, 7 suborders,[11][12] 16 families and 39 genera.[13]

References

  1. ^ a b c d e f g Boltovskoy D, Anderson OR, Correa NM (2017). "Radiolaria and Phaeodaria". In Archibald JM, Simpson AGB, Slamovits CH (eds.). Handbook of the Protists (2nd ed.). Springer International Publishing AG. pp. 731–763. doi:10.1007/978-3-319-28149-0_19. ISBN 978-3-319-28149-0.
  2. ^ a b Adl SM, Simpson AGB, Lane CE, Lukeš J, Bass D, Bowser SS, Brown MW, Burki F, Dunthorn M, Hampl V, et al. (2012). "The revised classification of eukaryotes". Journal of Eukaryotic Microbiology. 59 (5): 429–493. doi:10.1111/j.1550-7408.2012.00644.x.
  3. ^ Polet S, Berney C, Fahrni J, Pawlowski J (2004). "Small-subunit ribosomal RNA gene sequences of Phaeodarea challenge the monophyly of Haeckel's Radiolaria". Protist. 155 (1): 53–63. doi:10.1078/1434461000164. PMID 15144058.
  4. ^ a b Nikolaev SI, Berney C, Fahrni JF, Bolivar I, Polet S, Mylnikov AP, Aleshin VV, Petrov NB, Pawlowski J (2004). "The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes". Proceedings of the National Academy of Sciences. 101 (21): 8066–8071. doi:10.1073/pnas.0308602101. ISSN 0027-8424. PMC 419558. PMID 15148395.
  5. ^ Moreira D, von der Heyden S, Bass D, López-García P, Chao E, Cavalier-Smith T (2007). "Global eukaryote phylogeny: Combined small- and large-subunit ribosomal DNA trees support monophyly of Rhizaria, Retaria and Excavata". Molecular Phylogenetics and Evolution. 44 (1): 255–66. doi:10.1016/j.ympev.2006.11.001. PMID 17174576.
  6. ^ a b c Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, et al. (2019). "Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes". Journal of Eukaryotic Microbiology. 66 (1): 4–119. doi:10.1111/jeu.12691. PMC 6492006. PMID 30257078.
  7. ^ a b Nakamura, Yasuhide; Suzuki, Noritoshi (2015). "Chapter 9. Phaeodaria: Diverse Marine Cercozoans of World-Wide Distribution". In Ohtsuka, Susumu; Suzaki, Toshinobu; Horiguchi, Takeo; Suzuki, Noritoshi; Not, Fabrice (eds.). Marine Protists: Diversity and Dymanics. Springer Japan. pp. 223–249. doi:10.1007/978-4-431-55130-0_9. ISBN 978-4-431-55130-0.
  8. ^ Swanberg N, Bennett P, Lindsey JL, Anderson OR (1986). "The biology of a coelodendrid: a mesopelagic phaeodarian radiolarian". Deep Sea Research Part A. Oceanographic Research Papers. 33 (1): 15–25. doi:10.1016/0198-0149(86)90105-6.
  9. ^ Nakamura Y, Imai I, Yamaguchi A, Tuji A, Not F, Suzuki N (2015). "Molecular Phylogeny of the Widely Distributed Marine Protists, Phaeodaria (Rhizaria, Cercozoa)". Protist. 166 (3): 363–373. doi:10.1016/j.protis.2015.05.004. PMID 26083083.
  10. ^ Calkins GN (1926). The biology of the Protozoa. Lea & Febiger, Philadelphia, New York.
  11. ^ a b Cavalier-Smith T, Chao EE (2012). "Oxnerella micra sp. n. (Oxnerellidae fam. n.), a Tiny Naked Centrohelid, and the Diversity and Evolution of Heliozoa". Protist. 163 (4): 574–601. doi:10.1016/j.protis.2011.12.005. ISSN 1434-4610. PMID 22317961.
  12. ^ a b Cavalier-Smith T, Chao EE, Lewis R (2018). "Multigene phylogeny and cell evolution of chromist infrakingdom Rhizaria: contrasting cell organisation of sister phyla Cercozoa and Retaria". Protoplasma. 255 (5): 1517–1574. doi:10.1007/s00709-018-1241-1. PMC 6133090. PMID 29666938.
  13. ^ Takahashi K, Anderson OR (2000). "Class Phaeodaria" (PDF). In Lee JJ, Leedale GF, Bradbury P (eds.). Illustrated Guide to the Protozoa. Vol. II (2nd ed.). Society of Protozoologists, Lawrence, Kansas. pp. 981–994.
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