cy_titleTsukuba.jpg (16744 bytes)

 

I. Diagnostic Characters of the Blue-green Algae.

bullet How many are there? about 150 genera with about 2000 species.
bullet How old are they? 2.8 to 2.5 billion years old with stromatolites as living fossils.
bullet Where are cyanobacteria found?
bullet Many species in freshwater habitats including thermal springs and soil.
bullet Many species in marine habitats as well.
bullet In Hawai'i, Lynbya majuscula is probably our most common marine species.
bullet How are their cells organized? Bacterial organization.
bullet What pigments do they possess?
bullet Chlorophyll a and phycobilins assembled as a phycobilisome on thylakoid membranes.
bullet How is the chloroplast constructed?
bullet Thylakoids do not stack at all; they form NO grana.
bullet There are no chloroplasts.
bullet What storage product is made? 
bullet Cyanophycin starch {with alpha 1,4 linked glucans}.
bullet Cell wall features?
bullet These are gram negative bacteria with a 4 layered cell wall; murein (peptidoglycan)  as rigid structure.
bullet Many also possess polysaccharide matrix that envelopes cells (Anacystis) or sheath that cover cells in filaments (Lyngbya).
bullet Cells diversity and complexity is surprising for "bacteria". 
bullet A few species remain as unicells but show no sexual reproduction.
bullet Aggregations of cells into "trichomes" occurs  (Lyngbya).
bullet Filaments occur when trichomes are surrounded by a sheath.
bullet Cell differentiation results in "spores", akinetes and heterocysts.
bullet Take a look at this sampling of Cyanophytes.

II. Simple cell construction.

Anacystis

There is no sexual reproduction cycle know for this alga.

III. Developmental lineages.

Simple to increasingly complex (Order Chroococales).

bullet Anacystis
bullet Coccochloris
bullet Agmenellum

All of these genera reproduce asexually.

Increasing complexity but single cell that produces "spores" (Order Chamaeosiphonales).

bullet Entophysalis

Increasingly complex  morphologies (Order Nostocales) with   cell differentiation into heterocysts and false branching in some genera.

bullet Anabaena
bullet Calothrix
bullet Cylindrospermum
bullet Rivularia
bullet Tolypothrix

All of these genera reproduce asexually

Most complex morphology result in the most advanced order, the Order Stigonematales. This group of  bluegreens exhibits multicellular growth via true branching.  Heterocysts still occur.

bullet Stigonema
bullet Hapalosiphon

All of these genera reproduce asexually.

IV. Recap major themes.

Increasing complexity shown in morphologies and cell differentiation.

V.  Hot Links

Stromatolites, as living fossils Archaebacteria
Images of Mars - early Earth environments? Other  planets  as cyanophyte niches?
Azolla and Anabaena;   Nostoc Nitrogen fixation and history
Cyanotech web site Cyanotech at Natural Energy Lab
Acid river for cyanophyte niche? Local Cyanotech makes good
Geologic time table Lake Erie blue green algae

This page is maintained by Celia Smith and intended for use by undergraduates and graduates, Botany Dept, Univ Hawai'i at Manoa.