The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters.[3] They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally they have the form of small amoebae, with branching cytoplasmic extensions that capture prey and connect the cells together, forming a net. These extensions are dependent on the presence of light and polymerization of the actin cytoskeleton.[4] They may also form flagellate zoospores, which characteristically have a single subapical flagellum that spirals backwards around the cell body, and walled coccoid cells.

Quick Facts Chlorarachniophytes, Scientific classification ...
Chlorarachniophytes
Thumb
Chlorarachnion reptans
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Cercozoa
Subphylum: Reticulofilosa
Class: Chlorarachniophyceae
Hibberd & Norris, 1984
Orders & Families
Synonyms
  • Chlorarachnea Cavalier-Smith, 1993, orth. zool.
  • Chlorarachniophyta Hibberd & Norris, 1984[1]
Close
Thumb
A cultured chlorarachniophyte, Lotharella globosa LEX01 strain [2]

The chloroplasts were presumably acquired by ingesting some green alga.[5] They are surrounded by four membranes, the outermost of which is continuous with the endoplasmic reticulum, and contain a small nucleomorph between the middle two, which is a remnant of the alga's nucleus. This contains a small amount of DNA and divides without forming a mitotic spindle. The origin of the chloroplasts from green algae is supported by their pigmentation, which includes chlorophylls a and b, and by genetic similarities. The only other groups of algae that contain nucleomorphs are a few species of dinoflagellates, which also have plastids originating from green algae,[6] and the cryptomonads, which acquired their chloroplasts from a red alga.

The chlorarachniophytes only include five genera, which show some variation in their life-cycles and may lack one or two of the stages described above. Genetic studies place them among the Cercozoa, a diverse group of amoeboid and amoeboid-like[clarification needed] protozoa.

The chlorarachniophytes were placed before in the order Rhizochloridales, class Xanthophyceae (e.g., Smith, 1938), as algae, or in order Rhizochloridea, class Xanthomonadina (e.g., Deflandre, 1956), as protozoa.

So far sexual reproduction has only been reported in two species; Chlorarachnion reptans and Cryptochlora perforans.[3]

Morphology

Thumb
Representation of a Chlorarachniophyte
  1. Filopodium
  2. Extrusomes
  3. Mitochondrion, creates ATP (energy) for the cell (flat cristae)
  4. Capping vesicle
  5. Golgi apparatus, modifies proteins and sends them out of the cell
  6. Nucleomorph
  7. Plastid membranes (4, secondary green)
  8. Stacked thylakoid, site of the light-dependent reactions of photosynthesis
  9. Pyrenoid, center of carbon fixation
  10. Globules
  11. Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell
  12. Nucleolus
  13. Nucleus
  14. Prey in phagosome
  15. Digestive vacuole

Phylogeny

Based on Shiratori et al. 2024.[7]

Chlorarachniophyceae
Chlorarachniales

Amorphochlora amoebiformis

Viridiuvalis adhaerens

Gymnochlora dimorpha

Gymnochlora stellata

Lotharella

L. globosa

L. oceanica

L. reticulosa

L. vacuolata

Partenskyella glossopodia

Chlorarachnion reptans

Norrisiella sphaerica

Bigelowiella natans

Bigelowiella longifila

Chlorarachnida
Minorisida

Minorisa minuta

Minorisa fusiformis

Minorisa megafusiformis

Minorisa magna

Rhabdamoeba marina

Chlorarachnea

Taxonomy

  • Class Chlorarachniophyceae Hibberd & Norris 1984[8] [Chlorarachnea Cavalier-Smith 1998; Chlorarachniophyta Hibberd & Norris 1984; Chlorarachnia Cavalier-Smith 1993]
    • Order Minorisida Cavalier-Smith 2017[10]
    • Order Chlorarachniales Ishida & Hara 1996 [Chlorarachniida Hibberd & Norris 1984]
      • Family Chlorarachniaceae (Pascher 1939) Ishida & Hara 1996
        • Genus Amorphochlora Ishida, Yabuki & Ota 2011
          • Species Amorphochlora amoebiformis (Ishida & Hara 1996) Ishida, Yabuki & Ota 2011 [Lotharella amoeboformis Ishida & Hara 1996]
        • Genus Bigelowiella Moestrup 2001
          • Species B. longifila Shuhei, Kunihiko & Kenichiro 2007
          • Species B. natans Moestrup 2001
        • Genus Chlorarachnion Geitler 1930
          • Species Chlorarachnion reptans Geitler 1930
        • Genus Cryptochlora Calderon-Saenz & Schnetter 1987
          • Species Cryptochlora perforans Calderon-Saenz & Schnetter 1987
        • Genus Gymnochlora Ishida, Nakayama & Hara 1996
          • Species G. dimorpha Ota 2011
          • Species G. stellata Ishida, Nakayama & Hara 1996
        • Genus Lotharella Ishida & Hara 1996
          • Species L. scrobicolata Ishida & Hara
          • Species L. polymorpha Dietz et al. 2003
          • Species L. vacuolata Ota & Ishida 2005
          • Species L. oceanica Ota 2009
          • Species L. reticulosa Ohta 2012
          • Species L. globosa (Ishida & Hara 1994) Ishida & Hara 1996 [Chlorarachnion globosum Ishida & Hara 1994]
        • Genus Norrisiella Ota, Ueda & Ishida 2007
          • Species Norrisiella sphaerica Ota, Ueda & Ishida 2007
        • Genus Partenskyella Ota et al. 2009
          • Species Partenskyella glossopodia Ota et al. 2009
        • Genus Viridiuvalis T.Shiratori, S.Fujita, T.Shimizu & K.Ishida 2017[11]
          • Species Viridiuvalis adhaerens T.Shiratori, S.Fujita, T.Shimizu & K.Ishida 2017

References

Wikiwand in your browser!

Seamless Wikipedia browsing. On steroids.

Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.

Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.