Haematococcus pluvialis (Flotow, 1844)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: cattle trough


Phylogenetic tree: Haematococcus pluvialis



  • cell spherical or ellipsoidal
  • cell covered by large, spherical envelope
  • spherical envelope limited by distinct membrane
  • cell connected to membran with fine filaments
  • two flagella guided in tubes through spherical envelope
  • length 10–50 µm (of cell)
  • one eyespot in anterior third
  • several, scattered contractile vacuoles
  • nucleus central with spherical nucleolus
  • one chloroplast, cup-shaped with many pyrenoids
  • central part of cell filled with orange or red haematochrome granules
Haematococcus pluvialis

Haematococcus pluvialis is an extremely common, volvococcal alga. It is found in small and very small bodies of water, such as rock puddles, cattle troughs or bird baths, which can dry out regularly and are exposed to intense sunlight in summer. The algae can therefore cope with the most extreme conditions. When the water points dry out, the cells encyst and form red-orange coatings.


The most striking feature of Haematococcus pluvialis is the large, spherical envelope with a distinct membrane in the middle of which the cell is located. It is attached to cytoplasm filaments, which are connected to the outer membrane. These cytoplasm filaments are often dichotomously branched at the distal end. Apically, the cell has a nose-shaped projection from which the two flagella extend. They are guided outwards through the sphere by two hollow tubes. The cell is thus completely shielded from the environment by this construction. Another characteristic feature is the large amount of orange-red haematochrome granules (a mixture of carotinoids) that accumulate around the central nucleus. One can assume a function as UV protection.


Many small contractile vacuoles are distributed over the entire cell. The cell has a cup-shaped chloroplast with several pyrenoids (usually more than 4). This distinguishes Haematococcus pluvialis from the similar species Haematococcus droebakensis and Haematococcus Bütschlii, which have only two pyrenoids.


Haematococcus pluvialis is one of the few industrially utilized algae. It produces the carotenoid astaxanthin, which is used as a colorant in the fish (salmon), food and cosmetics industries. The increased formation of astaxanthin in direct sunlight is exploited.


Fig. 1 a-b: Haematococcus pluvialis. L = 34 µm (of cell). Two focal planes of a freely swimming specimen. Obj. 100 X.


Fig. 2 a-b: Haematococcus pluvialis. L = 38 µm (of cell). Two focal planes of a second, freely swimming specimen. ES = eyespot, F = flagellum, Nu = nucleus. Obj. 60 X.


Fig. 3 a-b: Haematococcus pluvialis. Two focal planes of a slightly squashed specimen. Note the scattered contractile vacuoles (CV) and pyrenoids (PY). The nucleus (Nu) is located centrally and surrounded by an accumulation of orange-reddish haematochrome granules (HC). The cell is connected via cytoplasm filaments (PF) with the outer membrane . Obj. 100 X.


Fig. 4: Haematococcus pluvialis. Two cells in a common spherical envelope after cell division. Obj. 60 X.


Fig. 5: Haematococcus pluvialis. In a strongly squashed specimen the scattered pyrenoids (PY) are visible and the nucleus (Nu) with a central nucleolus. One of the tubes (TU) is in the focal plane, which guides the flagellum (F) through the spherical envelope and membrane. CV = contractile vacuole, ES = eyespot, HC = haematochrome granules, SM = spherical membrane. Obj. 100 X.