The Chlorarachniophyceae are a recently described class of amoeboid unicells with cytoplasmic extensions (filose pseudopods) that hold them together in a loose colony and also capture bacteria Hibberd and Norris 1984).  They are mixotrophic, both photosynthetic and heterotrophic (ingesting bacteria).

Chloroplasts are surrounded by four membranes indicating a primary and secondary endobiosis.  A nucleomorph - remains of the nucleus of an endobiont - is located between the two pairs of membranes.

Motile cells occur with a single emergent flagellum and a second basal body indicating a biflagellate ancestry.  Cysts may be formed from the motile cells (Moestrup and Sengco 2001).

Hibberd, D.J. and R.E. Norris  1984.  Cytology and ultrastructure of Chlorarachnion reptans (Chlorarchniophyta Divisio nova, Chlorachniophyceae Classis nova).  Journal of Phycology 20(2): 310-330.

Moestrup, Ø. and M. Sengco  2001. Ultrastructural studies on Bigelowiella natans, gen. et sp. nov., a Chlorarachniophyte flagellate. Journal of Phycology 37(4):624-646,