The Chlorophyta are a division of almost 8000 species, most of which are fresh water species.. However some can be found in the most unexpected places... such as growing on snow packs, in soils, on trees, as symbionts in lichens or symbionts of protozoans & hydras. Calcified green algae are important components of marine sediments and beaches and can be found attached to bedrock over 150 meters deep.
Their fossil record extends back a Billion years ago with fresh water species evolving approximately 450 MYA. .
They are considered to be ancestral to land plants for their following attributes:
- Like land plants they have chlorophyll a & b, and cartenoids in their chloroplasts... thus appear green though some are more yellowish or black due to the addition of cartenoids ( accessory pigments)..
- They use starch as their storage product.. just like most of the angiosperm or higher plants you normally consider..
- Their flagella ( only motile stages) are 2 or more anterior or laterally inserted, of equal size and whiplash
- Their cell wall is made up of cellulose, hemicellulose and pectins ( think of the stuff you put into jellies to 'gel' them up.
Within the division, there are 3 classes:
- Chlorophyceae
- Charophyceae.. some taxonomists consider them to form their own phyta and designate them as the Charaphyta. For now we keep them downgraded as a subset of the Chlorophyta...
- Ulvophyceae
Before we go over these classes, let's review some primary concepts:
Evolution of colonial body types vs evolution of filamentous & parenchymatous morphology vs. coenocytic bodyLife cycles: sporic vs.gametic vs. zygotic meiosis
Placement of flagella and microtubules
Phragmoplasts/phycoplasts
Now, back to the groups:
Class Chlorophyceae
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