Chroococcales

Aphanothece (a-fan-owe-theek-ee) blue green alga in which many coccoid or cylindrical cells share a common mucus sheath. Phase contrast.

Aphanothece (a-fan-owe-theek-ee) blue green alga in which many coccoid or cylindrical cells share a common mucus sheath. Differential interference contrast.

Microcystis aeruginosa (Kützing, 1833) F.T. Kützing, 1846.Collected from a freshwater aquaculture tub near Boise, Idaho December 2005. DIC

Of the genus Microcystis (Cyanobacteria, chroococales), M. wesenbergii is the easiest species to identify: the spherical cells are relatively large (5-8 µm) and are embedded in thick colorless homogeneous mucilage with clearly defined contours. It is generally less abundant in Lake Kinneret than M. aeruginosa and M. flos aquae.

Microcystis flos-aquae together with Microcystis aeruginosa is common in Lake Kinneret throughout the year, and blooming periodically. The cells at the border and at the center of Microcystis colony looks different by chlorophyll and gas vesicles concentrations. The specimen was sampled from the shore of the lake in March 2006.

Microcystis flos-aquae (Cyanobacteria, Chroococcales) is a together with Microcystis aeruginosa are common in Lake Kinneret throughout the year, occasionally forming blooms with surface scums in winter or spring. The individual cells in a M. flos-aquae colony are 3-4 um in diameter, the colony is spherical or lens-shaped, with varying degree of spacing between cells within a colony. The dark spots clearly showing in the individual cells in this picture are due to the reflection of light from the gas vesicles. A bunch of choanoflagellates are attached at the upper left side of the colony.

Chroococcus turgidus, (Cyanobacteria, Chroococales), from Lake Kinneret pelagic waters, April 2006, showing 2 daughter cells after division by simple binary fission – as characteristic for most Chroococcales species. This species is common in the plankton of Lake Kinneret throughout the year. Usually there are 2 – 8 cells in a colony. Clearly delimited colorless mucilaginous envelopes surround the individual cells following their contours, and the entire colony. Cell diameter: 8 – 11 µm.

Chroococcus turgidus (Cyanobacteria, Chroococcales) is common in Lake Kinneret in recent years. In this unusual photograph a choanoflagellate is attached to its outer shell.

Chroococcus (crow-o-cock-us), large cyanobacterium, typically two (but sometimes one) cells enclosed within a mucus sheath. Photosynthetic pigment distributed through cytoplasm, which may have a granular texture, but does not have subcompartments (organelles). Differential interference contrast.

Chroococcus (crow-owe-cock-us) coccoid cyanobacteria, adhering to each other to form extensive flat sheets, no evident mucus sheath or heterocysts. Differential Interference Contrast.

Chroococcus (crow-o-cock-us), large cyanobacterium, typically two (but sometimes one) cells enclosed within a mucus sheath. Photosynthetic pigment distributed through cytoplasm, which may have a granular texture, but does not have subcompartments (organelles). Differential interference contrast.

Chroococcus (crow-owe-cock-us) tentative identification. Coccoid blue green algal cells. Found as one of several cyanobacterial epibionts on the leaves of the moss Hygrohypnum, a site which seems to be a focus for nitrogen fixation. In this case the cyanobacterial cells have occupied one of the cortical cells of the plant. Differential interference contrast.

Chroococcus (crow-owe-cock-us) tentative identification. Coccoid blue green algal cells. Found as one of several cyanobacterial epibionts on the leaves of the moss Hygrohypnum, a site which seems to be a focus for nitrogen fixation. Differential interference contrast.

Chroomonas. Cell observed in freshwater sediments in the vicinity of Broome, Western Australia in September 2003. This image was taken using differential interference contrast optics. Â Â This work was supported by the Australian Biological Resources Study.

Variously sized individuals - some species have been reported with at least a five fold size range - so these may be of a single species. Nomarksi, diferential interference contrast optics.

Large blue-green algal (cyanobacterial) cells in mucus sheath. Differential interference contrast optics. 

Blue green algae in a mucus sheath. Differential interference contrast optics.

Most Chroococcus cells are quite large. Some empty capsules can be seen to the right of the living cells. Differential interefence contrast optics.

The chroococcus cells are to the right, and the cells of a similar size but a brighter green colour to the left are cells of an unidentified chlorophycean green alga (a eukaryote). This image illustrates the blue-green colour from which the blue-green algae get their name. Differential interference contrast optics.

Typical arrangement with paired cells inside a mucus sheath. Differential interference contrast optics.

Anacystis (a-na-cyst-is) is a cyanobacterium in which globular cells are located within a gelatinous matrix. Some of the cyanobacteria with this form can be toxic. Differential interference contrast.

Anacystis (a-na-cyst-is), a cyanobacterium or blue green algae, in which the cells are clumped together within a mucus material. The clusters have to be compressed so that the individual cells can be observed. This genus adopts a variety of forms. Some Anacystis species are known to produce toxins. Phase contrast.