Chlorarachniophytes are marine unicellular algae that live widely in the coastal and oceanic waters of temperate to tropical zone. They possess green plastids (chloroplasts) that have originated from a green algal endosymbiont via a secondary endosymbiosis. The plastid is accompanied by a reduced nucleus of the endosymbiont, called a nucleomorph, which still contains a highly reduced and compacted eukaryotic genome.

Keywords: algae; Cercozoa; Chlorarachniophyceae; nucleomorph; secondary endosymbiosis

Figure 1.

Three types of chlorarachniophyte cell: (a) amoeboid cells of Lotharella amoebiformis, (b) coccoid cells of Lotharella vacuolata and (c, d) flagellate cells of Bigelowiella longifila. F, flagellum; P, plastid; Fp, filopodium and N, nucleus.

Figure 2.

Transmission electron micrograph of a chlorarachniophyte cell. P, plastid; M, mitochondrion; N, nucleus and Py, pyrenoid.

Figure 3.

Three examples of chlorarachniophyte life cycles. (a) Life cycle of Lotharella vacuolata. (b) Life cycle of Bigelowiella longifila. (c) Life cycle of Lotharella globosa. A, amoeboid cell; C, coccoid cell; Cy, Cyst; DC, daughter cells; FC, flagellate cell (zoospore); VD, vegetative division and WA, walled amoeboid cell. Broken lines show predicted processes.

Figure 4.

Schematic drawing that explains the process of the primary and secondary endosymbioses. CB, cyanobacterium‐like organism; P, plastid; M, mitochondrion; N1, symbiont nucleus; N2, host nucleus and Nm, nucleomorph.

Figure 5.

Transmission electron micrograph of Lotharella sp., showing a plastid and a nucleomorph in the periplastidal compartment. Arrow indicates gap in the nucleomorph envelope membranes. Nm, nucleomorph; P, plastid and asterisk (*), periplastidal compartment.



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Further Reading

Pickett‐Heaps JD and Pickett‐Heaps J (2006) The Kingdom Protista: The Dazzling World of Living Cells. Australia: Cytographics [DVD].

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How to Cite close
Ota, Shuhei, and Ishida, Ken‐ichiro(Apr 2008) Chlorarachniophytes. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0003060.pub2]