Title
Monterey Bay Aquarium Research Institute
Marine Botany

Phytoplankton


CYANOBACTERIA QuickFacts

 

Figure 1.  A light micrograph of Synechocystis sp. - a common bloom-forming marine cyanobacterium.  These cells are only about 2 um.  Photo used with permission from owners: Jeff Johansen (John Carroll University), Mark Schneegurt (Wichita State University) and Cyanosite (http://www-cyanosite.bio.purdue.edu/index.html). 

 

Cyanobacteria - also known as "blue-green algae" - are the most ancient life form known to inhabit earth, with a fossil record of over 3.5 billion years.  They are procaryotic cells, so do not have organelles the way eucaryotic cells do.  In fact, eucaryotic plants are the product of endosymbiosis between ancient relatives of extant cyanobacteria ("cyanocyte" below) and non-photosynthetic cells ("phagocyte" below), which engulfed or phagocytosed them.  

 

ENDOSYMBIOSIS MOVIE

Figure 2. Endosymbiosis occurs between a phagocyte, a cell 

that incorporates another cell into its cytosol, and a cyanocyte, 

a hypothetical relative of the extant cyanobacteria.   

(Movie file size: 120 kb)

 

Cyanobacteria can be found as solitary cells, as shown in the image above, or in long filaments.  Often, the filamentous forms can produce large mats which can be attached to the benthos or float in the water.  If you have a filament, look for the occasional heterocyst cell, which is larger than the simple vegetative cells.  Heterocysts are the specialized cells of nitrogen fixing cyanobacteria that convert diatomic atmospheric nitrogen (N 2 ) into biologically available forms, nitrate and nitrite. 

Figure 3. Thick-walled nitrogen-fixing heterocyst,

 flanked by vegetative cells.

 

Cyanobacteria are very important members of aquatic ecosystems.  To find out more about them, go to Cyanosite, a website devoted to the fascinating world of cyanobacteria.  

 

Cyanobacteria QuickFacts:

Cell size: ~ 2 m m

Cell wall: peptidoglycan

Chloroplasts: none, single thylakoid membrane

Photo-pigments: chlorophyll a, phycobilins, carotenoids

Reproduction: simple cell division, filament fragmentation, spores

Ecological roles: nitrogen fixation, toxin producers, blooms

Common genera:   Oscillatoria, Synechococcus, Spirulina

back to the top of page


 wpeF.jpg (16876 bytes)wpe11.jpg (6061 bytes)silico4_small.jpg (64518 bytes)cocco-Emiliania.gif (21926 bytes)wpe3.jpg (46852 bytes)wpe13.jpg (7588 bytes)