Nicaragua 2011: Selva Negra - Green harvestman (Opiliones: Sclerosomatidae). The green colour is not actually part of the harvestman and not all individuals posses it. The colour is provided by a thin film of green photosynthetic cyanobacteria that have colonized its dorsal surface. Recent research suggests that this may be an example of a mutualistic partnership where both parties benefit. The cyanobacteria gets a mobile platform on which to grow, and the harvestman gets better camouflage.