Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981). The species have mostly been known from the marine environment but also occur in fresh and brackish water. All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy. The characterisation is mostly done by rbcL gene and 18S rRNA sequence analysis.
The algae of the genus Nannochloropsis differ from other related microalgae in that they have chlorophyll a and completely lack chlorophyll b and chlorophyll c. In addition they are able to build up a high concentrations of a range of pigments such as astaxanthin, zeaxanthin and canthaxanthin.
They have a diameter of about 2 to 3 micrometers and a very simple ultrastructure with reduced structural elements compared to neighbouring taxa.
Nannochloropsis is considered a promising alg