Chromera velia: Coral symbiont or parasite?

[Extract] The discovery of a novel alga, Chromera velia, has generated much interest because it is a missing link between the non-photosynthetic apicomplexan parasites and dinoflagellates, which includes the coral endosymbiont Symbiodinium (Moore et al. 2008). Janouskovec, this new algal species has only been found in association with corals, having now been isolated from multiple coral species from a range of reefs worldwide (Moore et al. 2008; Cumbo et al. 2012; Janouskovec et al. 2012). C. velia can be endosymbiotic in coral larvae (Cumbo et al. 2012), and can also persist in culture, however, due to its close relationship to apicomplexans it may become parasitic under some conditions (Obornik et al. 2011). In support of this potential shift to parasitism, organelles putatively specialised for cell or host invasion are formed when C. velia is free-living and motile (Obornik et al. 2011).