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Dr. Celia Smith's Reef Algae Website

Link to "Seaweeds of Hawaii" by W. H. Magruder and J. W. Hunt

Diversity = Large compared to other algae.GreenAlgalMatFalls.jpg (36916 bytes)

Genera = 450 & Species = 7,000

Color

The colors of Chlorophyta range from Green to Orange. The orange color is due to Carotenoids which form the Accessory Pigments for this Division.

Their Photosynthetic Pigments are Similar to those of Vascular Plants.

Chlorophyll a, b are typically present Ulva_habitCrop.jpg (46350 bytes)along with

a, b Carotene plus Xanthophylls.

The Cell Wall is very similar to that of terrestrial plants because its main components are Cellulose & Pectins.

Some species deposit Calcium Carbonate in their walls.

Halimeda is a good example of this.HalimedaOpuntia.jpg (24715 bytes)

Occurrence

This Division has a larger number of Freshwater species than Marine species. Marine species tend to be larger than those found in freshwater. However, the Chlorophyta do not produce organisms that approach the size of large Kelps

A few species exist on snow fields andAlgaeAntarcticSnow.jpg (23037 bytes) Glaciers. They tend to have high concentrations of Carotenoids which are responsible for the red hue of their cells. These are called "Snow Algae". They can be found in the Rocky Mountains, the Cascades, the Arctic and Antarctic, as well as most areas where there are permanent or semi-permanent snow-fields. It would be interesting to see if they occurred on the volcanic peaks of Hawai'i.

This was the first research project I elected to study when I was in graduate school. Long hikes with a backpack filled with bottled smow algae and 100+ degree temperatures in the laboratory converted me into a lab-scientist.

RedSnowClean.jpg (20946 bytes)
Untroden Red Snow		 RedSnowstreak.jpg (44077 bytes)
Red Snow containing footprints of a Yeti named David Webb

A few species are Terrestrial.

trentepohlia-eljunque500.jpg (291254 bytes)
Trentepohlia eljunque is Terrestrial

Life Modes - They are predominately Autotrophs.FlagelatedCellHue.jpg (11097 bytes)

Some species form Symbioses with Lichens, Hydras & Mollusks.

Ultrastructure

They are Eukaryotes and have the "Usual Suspects" when it comes to organelles.ChlamydomonasEMLab300.jpg (86379 bytes)

Some species form Cell Plates during Mitosis, that are similar to those found in land plants.

Some species have Flagella. However, flagellated cells are usually Gametes or Spores

Chloroplasts have the typical Double Boundary Membrane. This is similar to land plants.

The Thylakoids can produce Parallel Bands of Three, Irregular
Stacks as well as Grana.

ChlpStack3.jpg (21025 bytes) IrregChlpShape260.jpg (31404 bytes) ChlpGrana260.jpg (18290 bytes)
Chloroplast with Irregular Bands of  Stacked Thylakoids Chloroplast Bands of 3 Thylakoids Chloroplasts with Grana

Chloroplast Shape varies. The trend is towards an increase in Surface Area.

Common Chloroplasts Shapes include

Cup     Filament    Star    Reticulate (Net)     Banded

A few have the Discoid Shape of most Terrestrial Plants
Spirogyra-2-200.jpg (10916 bytes)
Spirogyra has spiral Chloroplasts		 UlothrixLgCrop.jpg (72988 bytes)
Ulothrix has band-shaped Chloroplasts		 Zygnema240.jpg (28562 bytes)
Zygnema has Star-shaped Chloroplasts
ChlamyYTsukiNihon300.jpg (6380 bytes)
Chalmydomonas has one cup-shaped Chloroplast		 CladophoraCPlasts300.jpg (41534 bytes)
Cladophora has many small oval Chloroplasts		 MougeotiaLarge300.jpg (32932 bytes)
Mougeotia has a flat Chloroplast. The disk-like areas are Pyrenoids.

Pyrenoids occur in most species.

Starch is the major storage product. Starch is stored in the Stroma of the Chloroplast. This is similar to land plants.

This is unusual for Algae. It tends to make the Chloroplasts have a lumpy appearance.  Note the Chalmydomonas above.

Most Algae store Starch in the Cytoplasm.

MougeotiaLargeChlplastMax.jpg (46090 bytes)

 PyrenoidChlamyLab.jpg (55954 bytes)
Light Microscope Photo of Pyrenoids in Mougeotia Chloroplast EM Photo of a Pyrenoid in Chlamydomonas

Morphological Diversity

There is a wide range of morphological diversity .

There are Unicellular, Filamentous, Siphonous, Multicellular, Colonial, Parenchymatous, Motile, Nonmotile types.

golenkinia2.jpg (5235 bytes)
Golenkinia a Unicellular Form

VolvoxComboVis.jpg (101699 bytes)
Volvox is a Colonial Alga

 MicrothamnionLg500.jpg (112008 bytes)
Microthamnion is a Filamentous Alga

Microthamniop300.jpg (136062 bytes)
ColeochGood.jpg (97896 bytes)
Coleochaete is Parenchymatous

Their Size Ranges from microns to meters (8m=the largest).

The Chlorophyta have been divided into several Classes by Taxonomists. There is no, one absolute classification system at this time. I will present a more traditional scheme to organize these lectures. I am not going to stress Taxonomy. However, I will mention some of the major groups as we study their morphological and reproductive adaptations. I want you to see the major morphological and reproductive trends for this division as well as the progression of traits which could have led to the first truly land plants. Dr. Smith offers several courses which look critically at algal Taxonomy, Ecology & Physiology.

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