Editing Chloroplast (section)

==== Chlorarachniophytes ====
{{See also|Chlorarachniophyte}}
[[File:Chlorarachnion reptans.jpg|thumb|left|''[[Chlorarachnion reptans]]'' is a chlorarachniophyte. Chlorarachniophytes replaced their original [[red algal]] endosymbiont with a [[green alga]].]]

[[Chlorarachniophytes]] are a rare group of organisms that also contain chloroplasts derived from green algae,<ref name="Keeling-2004" /> though their story is more complicated than that of the euglenophytes. The ancestor of chlorarachniophytes is thought to have been a eukaryote with a ''red'' algal derived chloroplast. It is then thought to have lost its first red algal chloroplast, and later engulfed a green alga, giving it its second, green algal derived chloroplast.<ref name="Keeling-2010" />

Chlorarachniophyte chloroplasts are bounded by four membranes, except near the cell membrane, where the chloroplast membranes fuse into a double membrane.<ref name="Kim-2009" /> Their thylakoids are arranged in loose stacks of three.<ref name="Kim-2009" /> Chlorarachniophytes have a form of polysaccharide called [[chrysolaminarin]], which they store in the cytoplasm,<ref name="Keeling-2010" /> often collected around the chloroplast [[pyrenoid]], which bulges into the cytoplasm.<ref name="Kim-2009" />

Chlorarachniophyte chloroplasts are notable because the green alga they are derived from has not been completely broken down—its nucleus still persists as a [[nucleomorph]]<ref name="Keeling-2004" /> found between the second and third chloroplast membranes<ref name="Kim-2009" />—the [[periplastid space]], which corresponds to the green alga's cytoplasm.<ref name="Keeling-2010" />