WB01343_.gif (599 bytes)    Cyanobacteria   WB01345_.gif (616 bytes)
Link to Dr. Smith's Web Page on Cyanophyta WB01436_.gif (236 bytes)

Link to "Seaweeds of Hawaii" by William H. Magruder and Jeffrey W. HuntWB01436_2.gif (236 bytes)

Color = Blue Green - Rust - Black

OscillatoriaHand.jpg (29244 bytes)
Oscillatoria au natural
BGAHabitatLassen240.jpg (50854 bytes)
Unknown Cyanobacterium from a warm spring near Mt. Lassen (CA)

PigmentationLyngbib200Lab.jpg (53960 bytes)

Chlorophyll (a)

Diversity = Species 200 - 7500


Fresh Water -> Greatest Abundance & Diversity

Salt Water Lyngbya majuscula is the most common Marine Species in Hawaii.Reef-3D-Lab.jpg (81644 bytes)

Planktonic (few species) Important source for fixed Nitrogen

Intertidal Reef Platform

Fringing Reef Platform

Rubble Intertidal Zone in "Ooid Sand Grains"


Surface Crusts which appear lifeless, are revived following significant rains. These dry to a brittle crust as theCyanoMiCrust.jpg (91063 bytes) substrate looses water. These can be ecologically significant because they add biomass and Nitrogen to barren areas. This is a long-term process, however. These crusts can be seen in places like Arches National Park (Utah) where it is very dry & there is little ground cover or litter.

This can also be seen locally on abandoned,NostocNodules240.jpg (23852 bytes) dry lots. Heavy rains allow desiccated Cyanobacteria to flourish. They form undulating to round hydrated masses. These gradually shrink and crack as the substrate dries. They sometimes appear spherical.

Some Cyanobacteria (CBs) are also found in "green snow" which appears in the springtime on semi-permanent snowfields and glaciers.

Endolithic (Inside Rocks)

Cyanobacteria have recently found in the most barren area of Antarctica where no other life has been found. Similar observations have been made in the high Arctic. They live just below the surface of rocks. This sounds unbelievable but it is true.

Cyanobacteria can also inhabit carbonatic substrates like Limestone. (http://bio.bu.edu/~golubic/marine-cyano.html).

Some species inhabit the Calcium Carbonate secreted by Coralline Algae.

CyanoHyellaStella300Crop.jpg (30898 bytes)
Hyella stella: a Cyanobacterium that lives in Marine Limestone

ScytonemaEndolithicum.jpg (83799 bytes)

Scytonema endolithicum

Organisms like this can live in Coral Rubble which rolls about as "sand". Consequently, they inhabit a reef zone that would otherwise be unavailable to them, due to the absence of a stable substrate and the presence of vigorous wave action which would be unfavorable for Planktonic algae. These areas are often turbid due to wave & wind action and from soil runoff.

OoidGrain300Lab.jpg (38886 bytes) "Ooid" sand grain containing Endolithic Cyanobacterium (CB).

The presence of these organisms in limestone & coral reefs can lead to erosion. This is caused by grazing animals who eat the Cyanobacteria and consequently decrease the amount of limestone present. The effect of this is illustrated below.

IntertidalNotchHue400Lab.jpg (125092 bytes)
Erosion caused by Endolithic Cyanobacteria
Biokarst.jpg (33814 bytes)
This can sometimes produce fantastic "Biocarst" shapes.

Cyanobacteria that live in hot springs can deposit limestone therein. This accounts for the various cascading "sculptures" that can be seen in some of these areas (Yellowstone Park). Some Marine species precipitate Calcium Carbonate (Limestone). Consequently, they become a part of the reef building biota.

YellowstoneBGA.jpg (99488 bytes) YellowSyong.jpg (155888 bytes)
Hot Spring at Yellowstone Park: The dark color is due to the presence of Cyanobacteria. Limestone deposit at Yellowstone Park. The localized areas of green are  due to the presence of Cyanobacteria

Stromatolites (Stromatoliths) StromatolyteThinSection.jpg (19511 bytes)are large columnar Calcium Carbonate structures produced by Cyanobacteria. They accumulate slowly over immense time-spans. These were abundant in primeval times and constitute some of the oldest fossils. They can still be found today, particularly in Australian Tidal Flats. They are multilayered deposits that form in shallow pools where the climate is warm. The oldest Stromatolites are from the Precambrian and are 2.7 Billion Years-old!

CBs are thought to be the oldest Oxygen producing organisms. They profoundly changed the earth's atmosphere and allowed for the evolution of organisms that can use oxygen for respiration.

CyanoFossil.jpg (19447 bytes)
Fossil Cyanobacteria

Stromatoliths400.jpg (75126 bytes)
Illustration showing Fossil Stromatolites
FossilBGA400.jpg (146811 bytes)
Limestone deposit from ancient Cyanobacteria

(Glacier Park, Montana)
StromatolytesBeach.jpg (92174 bytes)
Living Stromatolites on the Beach
ThromboheadsUnWater.jpg (32764 bytes)
Stromatolites under water.

Life Modes

Most species are Autotrophic

Some are Epiphytic or Epizooic (Polar Bear)

Some are Symbiotic

Cyanobacteria are involved in several symbioticBlueLichen.jpg (189449 bytes) associations.  CBs can fix atmospheric N which becomes available for its symbiotic partner.

Lichens: Cyanobacteria are frequently the Photosynthetic partners of Fungi that compose Lichens. Lichens are important pioneer organisms which inhabit extremely difficult sites that may be dry, hot, cold,windy or all of the above.

Hornworts: (Anthocerophyta) have EndophyticHornwortdendrocerosnostoc.jpg (73080 bytes) (inside-plant) Cyanobacteria which reside in mucilage filled chambers within the thallus. Hornworts are colonizers and inhabit wet, unstable sites. The ability to get N from the CBs is extremely advantageous because N is usually a limiting element in terrestrial environments. As they decay Hornworts release their N which becomes available for more complex plants. Species in the Anthocerophyta can be seen near eroded and trampled areas in the local mountains.

Azolla: The aquatic fern Azolla (Pterophyta) forms aAzolla.jpg (191161 bytes) symbiosis with Nostoc species. These inhabit a cup-shaped area formed by the ventral leaves of the fern. The CBs fix nitrogen and release nitrogen-rich metabolites into the leaf cavity. These are absorbed by the Azolla which releases carbohydrates that are absorbed by the CBs. It is almostAnabaenaAzollaCrop.jpg (23125 bytes) impossible to separate the symbiotic partners once they become established. This relationship has been used for centuries in rice cultivation because it provides a cheap, renewable and pollution-free source of fertilizer.

Cycads: (Cycadophyta) form an interesting symbiosis with Nostoc. The CBs live in a circular zone that develops in upward growing root nodules. The nodules develop a special tissue layer that undergoes mitosis and autolysis in the presence of the CBs. Cycads occupy poor habitats and are almost extinct. Their symbiotic relationship with CBs is one reason why they still can be found in nature.

CycafMegaStrobOver300.jpg (136958 bytes)
CoralloidRootsLargeNature.jpg (75052 bytes)
Upward Growing Root Nodules
CycadNoduleX-S300.jpg (70625 bytes)
Cross Section through a root nodule showing the dark zone that contains Cyanobacteria.
CycadNodLSMacro400.jpg (83941 bytes)
Long Section through a Root Nodule: The dark areas contain Cyanobacteria.
NodAZCycasXSCommercLowMagLab.jpg (152965 bytes)
Commercial Cross Section showing the "Algal Zone" which contains CBs
AZLMSectTolBlLab.jpg (136109 bytes)
Thin section showing the Cyanobacteria in the "Algal Zone".

Gunnera: (Anthophyta) is a genus of flowering plants. These produce papillose outgrowths near the base of their enormous leaves. CBs are able to colonize these areas and even penetrate the cells in this structure. At least one Gunnera species grows in Hawaii. One of Dr. Lamoureux's former students worked on these plants.

GunneraLeavesPeople.jpg (285570 bytes) GunneraPetioles.jpg (244125 bytes)
Gunnera growing in Hawaii

Growth Forms

Single Cells -> Colonies -> Filaments -> Branched Filaments

Synechococcus.jpg (42395 bytes)
ChrococcusNihonCrop.jpg (23977 bytes)
Anacystis.jpg (44283 bytes)
Cells of Anacystis
Anacystir.jpg (53631 bytes)
Anacystis Colony
NostocNodulesCropHueLab.jpg (33078 bytes)
Nostoc Ball (Colony)
NostoColony.jpg (184307 bytes)
Microscopic View of a Nostoc Colony
NostocNihon500.jpg (64936 bytes)
Nostoc Filaments seen with Phase Microscopy
NostocFilamentsPhase240.jpg (80012 bytes)
Individual Noctoc Filaments from a large Colony

(Phase Microscopy)


AnabaenaBest.jpg (30865 bytes)
OscilatoriaLongNihon400Ctrast.jpg (30106 bytes)
OscillatoriaColony240Lab.jpg (74474 bytes) OscillatoriaEmbos.jpg (71073 bytes)
Planktothrix.jpg (31457 bytes)
Planktothrix sp.
Lyngbia.jpg (55196 bytes)
Lyngbya sp.
SpirulinaB.jpg (4316 bytes) SpirulinaClose300.jpg (27345 bytes)
Spirlina sp. have a Spiral filament Morphology but the individual cells resemble those of Oscillatoria.

Filaments may be Branched, Unbranched or Clustered

Calothrx.jpg (34830 bytes)
Tolypothrix.jpg (27979 bytes)
GleotrichiaColony240.jpg (15496 bytes)

Gleotrichia Colony

GleotrichiaHue.jpg (51065 bytes)
Gleotrichia Individuals
GloetricLab.jpg (44961 bytes)

Cell DivisionCellInvaginationLab.jpg (47388 bytes)

Plasma Membrane & Inner 2 Wall Layers

Invaginate & form a

Septum which grows

Grows Inward and

Separates the cells.

Intercellular Communication

Microplasmodesmata connect adjacent cells in the filament.

MicplasmLab.jpg (24624 bytes)

Cell Shape

Uniform -> Tapering -> Narrow Apical

Growth = General (No Apical Meristems)

Cell Types

Cyanobacteria are Prokaryotes.
They have No Nuclear Envelope &
No Membrane-Bound Organelles

AnabaenaBest300Lab.jpg (66267 bytes)

Vegetative Cell -> Photosynthesis

Typbgaem.jpg (60326 bytes)

Heterocysts have a Round Shape & Thick Cell Walls. They often appear to be devoid of contents at the light microscope level.

They have Photosynthetic Thylakoids which contain Chlorophyll a and the other photosynthetic pigments.

These are Invaginations of the Plasmalemma.

Cyanophycin Granules (CPG) contain Amino Acids carbohydrates.

AnabaenaPhaseContrast.jpg (46434 bytes)

NostocNihonCropHet.jpg (20294 bytes)
Heterocysts seen with different types of Light Microscopy
Heterocyst.jpg (60034 bytes)
Heterocyst seen with an Electron Microscope


Heterocysts are the sites for the fixation of atmospheric Nitrogen.

They are Vegetative cells that are converted into Heterocysts.

An Oxygen-free Anaerobic Environment is Required because Oxygen inhibits Nitrogenase

The Thick Cell Walls are relatively impervious to Oxygen and this helps to create an anaerobic environment inside the Heterocyst.

The internal Membranes are thylakoids that have lost Chlorophyll. They provide the sites for Nitrogenase.

Other cell contents are generally lost. This helps to explain the lack of detail seen with the light Microscope.

SEM of Rivularia sp. showing the Pore (arrow) that connects the Heterocyst (H) to a Vegetative cell (V) RivulariaSEMConnectHeteroVeg.jpg (27676 bytes)

Heterocysts are connected to the Vegetative Cells through a special pore in their end walls. These are much larger than the Microplasmodesmata.

AkineteHeterocystLMHigh300Lab.jpg (15127 bytes) AkineteEM400Lab.jpg (22711 bytes)

AkineteEMBlue400.jpg (133744 bytes)
Larger Image of an Akinete


Akinetes are Asexual Propagules.

These are also derived from Vegetative Cells.

These tend to be Elliptical in shape.

They have very thick walls.

Survive unfavorable Conditions

Many thylakoids can be seen with an Electron Microscope.
The Thylakoids  are NOT Not Organized
for Photosynthesis.

They contain Storage Products

Cyanophycin Granules (Amino Acids)


Cell Structure Ultrastructure-Prokaryote

Size = Small vs Eukaryotic

Smallest = 1u

Complex Cell Sheath & Wall


AnabaenaSheathHCystSheathLab.jpg (39461 bytes)
Anabaena with a nearly translucent Sheath: Identify the Round Smooth-looking Cell.
SolentiaAchromaticaSheathLab250.jpg (55584 bytes)

Some = Thin Watery

Others -> Thick & Fibrous

Composition = Acidic Polysaccharides similar to Pectins

Inner Layer is called the Glycocalyx due to the presence of Glycoproteins. These are proteins that contain Sugars as Sugar Amides.
A Glycocalyx is not present in all cases!

Provides a Buffering Microenvironment.


Observed in Some Species (Synechococus - Nostoc)

Extend from Wall through Sheath

Tubular - Protein Composition

60 nm x 1000 nm

Function Unknown - Secretion?

Surface Spines (Spinae)

Seen in some Marine Forms
(i.e. Synechococus) ->

Conical & Project from Surface

Helical Construction

Function ? Defense? ? Buoyancy?

Wall-1-300Lab.jpg (46161 bytes)

Cell Wall

Gram Negative Bacteria

Four Layers  - (100 A each)

Layer 4 = Outer Membrane - Enzymes

Some are Digestive Enzymes.

Layer 3 = Electron Transparent

Layer 2 = Mucopolymer (Glycoproteins)

Thicker in Certain Species  like Oscillatoria sp.

Akinetes -> This layer is Thicker

Provides Protection from the Environment this aids in
Asexual Reproduction

Layer 1 = Electron Transparent

Immediately Outside Plasmalemma


Present in Transverse & Lateral Walls

Associated with Gliding Movements

Function =Secretory?

Absence of Nuclear Envelope

Bacterial "Chromosome"

Center of Cell

Photosynthetic Apparatus

ThylakoidsThylakoidsAnabaena300Lab.jpg (42378 bytes)

Invagination of Plasmalemma

Number - Responds to Light Intensity

Low light -> ManyThylakoids.jpg (46140 bytes)

High Light -> Few

Oscillatoria Thylakoids = 20% Dry Weight

Principally Found - Peripheral Area of CellThylakoidsNostocLab.jpg (29208 bytes)

Various Appearances

Series of Layers




Freeze Etch -> Reveals Surface Particles (Fluid Mosaic Model)

Photosynthetic Pigments

Principal Light Harvesting Pigment Chlorophyll a

Accessory Pigments

Carotenoids B-Carotene & Zeaxanthin

Thylakoids have a Precise Spacing

This is partly due to Phycobilisomes300Lab.jpg (31193 bytes)the Phycobilisomes which are attached to the   Surface of the Thylakoids

Phycobilisomes contain Accessory Pigments for Photosynthesis

These are Water Soluble and are stabilized by bonds to Proteins.

phycobilisome.jpg (28474 bytes)

These include the following Pigments.

C-Phycocyanins Absorb Green-Yellow Light (615-620A).

Allophycocyanins Absorb Orange-Red (650-670A)

C-Phycoerythrin Absorbs Green Light  (495-570)

The Visible Spectrum

Light Reaching The Surface of the Earth

Peak approx. 500 nm

Drops Off at Higher & Lower Wavelengths

SpectrumLab500.jpg (106148 bytes)

Chlorophyll & Carotenoids

Broad Absorbency in the Blue

Drops Off in Green

Good Absorbency in Red Light

Poor Absorbency at 550-650 nm

Phycobillin Pigments

Phycoerythrin Good Absorbency 500 - 600 nm

Phycocyanin Good Absorbency 550 - 650 nm

Allophycocyanin Good Absorbency 600 - 675

If we combine al of these, including Chlorophyll there is good light absorption across the Visible Spectrum!

SpectrumLab500Combined.jpg (86828 bytes)

Good Coverage except at 500nm

Absorption of Light by Water

SpectrumWaterDepth450Lab.jpg (57961 bytes)

Red & Blue -> Preferentially Absorbed

Wavelengths 500 - 600nm Absorbed Least

This region of the Spectrum corresponds with
Absorption Spectra of Phycobillins.

Gas Vacuoles

Bacteria (Common)GasVacuoleCell240Lab.jpg (93521 bytes)


Common in Nature but Lost in Culture.


Membrane Bound

Proteinaceous Walls

(10% Cells' Protein)

Long CylindersGasVesicleLab.jpg (66229 bytes)

Conical Ends

Regulates Density of Cells

Controls Position in Water Column

Vesicles Fill with Gas <--> Collapse

Regulated by Photosynthesis

Ecological Significance

Algal Blooms (Gas Vacuoles NOT Regulated)

CB Float to Surface

Massive Reproduction

Toxins -> Kill other Organisms

BloomMicrocystsiAir.jpg (34951 bytes)
Aerial View of a Large Cyanobacterial Bloom
BloomMicrocystisB.jpg (18001 bytes)
Microcystis Bloom
MicrocystisLab.jpg (147108 bytes)
CyanophytaBloomHue.jpg (102493 bytes)
Cyanophyte Bloom

Nitrogen Fixation

Nostocaceae -> HeterocystsHeteroCloseLM.jpg (3077 bytes)

Marine Species with Heterocysts

Calothrix & Scytonema


These have enlarged Thick Walls -> The outer envelope is Bilayered.Heterocyst240.jpg (28953 bytes)

Outer Layer contains mostly Polysaccharide.

Inner Layer is composed of Glycolipids.

Internal Membranes have a
concentric to Reticulate Pattern

Lack Photosystem II
(Oxygen Releasing Step)

Nitrogenase is Sensitive to Oxygen which inhibits N-fixation.

N Fixation = Anaerobic

N Levels regulate Heterocyst Production`Low N levels stimulate heterocyst formation.

NonHeterocystic N-Fixation

Oscillatoria (Planktonic)

Fix N - Low Oxygen  (Paerl & Bebout 1988)

Associated with Movement (10 microns/Second)

Gliding & Rotating

Secretion -> Pores

Contractile Waves Mucilage

ReproductionAkineteHeterocystLMHigh300Lab.jpg (15127 bytes)


Hormogonia Gliding Fragment

Akinetes ->

Some Species

EnlargedAkineteEM400Lab.jpg (9321 bytes)

Thick Walls

Resist Heat - Drought - Cold





Ecological Roles

Terrestrial Environments

Pioneering Organisms contribute fixed nitrogen & some biomass.

They may be Free Living

Nostoc Balls can grow on bare soil including Volcanic Sites.

They can be Epiphytic and even Epizooic.

Their Symbiotic relationships with Lichens is ecologically important.

Other symbiotic relationships are significant of the plants which have them.

Azolla can carpet the surface of small lakes and ponds. This can be a major, local ecological effect.

The symbiosis with Hornworts (Anthocerophyta) may have ecological significance in Hawaii because Hornworts colonize disturbed sites like pig runs and runoff streams.

Fresh Water

Cyanobacteria can grow in thermal Hot Springs where algal photosynthetic organisms can't survive. They deposit limestone in the process. However, this is an extremely slow process.

They can grow in low light environments due to their Phycobillin pigments.CalothrixPairCropHue200.jpg (65118 bytes)

They Release Carbon & Nitrogen Metabolites which can stimulate the growth of other organisms.

They can grow at low Oxygen levels and may enrich the local Oxygen concentration because the produce O2.

Resist Grazing by Protists this can lead to enhanced Cyanobacterial populations that can lead to "blooms".

Their relatively high tolerance to heat can lead to "blooms" caused by thermal pollution.

Tropical Reefs

Reef-3D-BGA-Lab.jpg (95207 bytes)

They are abundant in the Fringing Reef Platform

They are also Part of Opportunistic Filamentous Algae which cling to larger organisms.

This can be a Highly Productive/Area

N-Fixation (Calothrix)

Their ability to Fix Atmospheric Nitrogen contributes Significantly to productivity of Benthic Communities.

They also can have associations with Macroalgae & Corals.

Their N-Fixation Rates Parallel those of Terrestrial Systems like the Alfalfa-Rhizobium symbiosis.

Some Hawaiian Marine Cyanobacteria

Link to Hawaiian Cyanobacteria from WB01436_1.gif (236 bytes)

"Seaweeds of Hawaii" by William H. Magruder and Jeffrey W. Hunt

Hormothamion enteromorphoides

Green Color - Delicate Filaments - Tangled with Other Species - Filaments 2 - 8 cm - Tidepools & Reef Flats

LyngmaMajuskla.jpg (12814 bytes)

Lyngbya majuscula

Black - Dark Gray - Red - Green - Yellow - Filaments 5 - 10 cm - Tangled with other species


Symploca hydnoides

Upright Triangular Shoots - Common Holdfast - Color = Black - Gray - Reef Flats

WB01342_.gif (412 bytes)