Ostreococcus tauri

Ostreococcus tauri is a unicellular species of marine green alga about 0.8 micrometres (μm) in diameter, the smallest free-living (non-symbiotic) eukaryote yet described. It has a very simple ultrastructure, and a compact genome.

As a common member of global oceanic picoplankton populations, this organism has a major role in the carbon cycle in many areas and often uses light receptors called phototropins to sense external light. Recently, O. tauri has been the subject of studies using comparative genomics and functional genomics, as it is of interest to researchers because of its compact genome and green lineage.