Rapaza

Rapaza
Differential interference contrast microscopy of R. viridis capturing a Tetraselmis phytoplankton (arrowhead) with the anterior part of its cell. Scale bar: 10 μm
Scientific classification
Domain:	Eukaryota
Phylum:	Euglenozoa
Class:	Euglenida
Clade:	Euglenophyceae
Order:	Rapazida Cavalier-Smith, 2016
Family:	Rapazidae Cavalier-Smith, 2016
Genus:	Rapaza Yamaguchi, Yubuki & Leander, 2012
Species:	R. viridis
Binomial name
Rapaza viridis Yamaguchi, Yubuki & Leander, 2012[1]

Rapaza viridis (Latin for 'green grasper') is a species of single-celled flagellate within the Euglenophyceae, a group of algae. It is the only species within the genus Rapaza, family Rapazidae and order Rapazida. It was discovered in a tide pool in British Columbia and described in 2012.

Rapaza viridis is the first known mixotroph (an organism that combines photosynthesis and ingestion of food) and kleptoplastic species within the phylum Euglenozoa. It eats microalgae by engulfing them—a process called phagocytosis—and then uses the chloroplasts from these algae to perform photosynthesis, altering the chloroplasts' structure in the process. In particular, Rapaza viridis can only feed on Tetraselmis cells native to their original environment, and will reject any other prey.

Due to its unique mode of nutrition and phylogenetic position, Rapaza viridis is considered an evolutionary step between phagotrophs and phototrophs with permanent chloroplasts. Scientists consider that the common ancestor of all Euglenophyceae (a group of algae) was similar to R. viridis. It likely stole chloroplasts from its prey—just like R. viridis—a behavior supported by the discovery of genes in Euglenophyceae that came from different types of algae through a process called horizontal gene transfer. After the divergence of R. viridis, the remaining Euglenophyceae acquired permanent plastids from Pyramimonas.