Algae are a large group of diverse organisms, ranging from microscopic to macroalgae. In general, the term algae refers to any plant-like species which are aquatic and usually photosynthetic. These lack true roots, stems and leaves. They occur in both sea and fresh water. 

 

There are three main groups of algae:

 

 

The Brown Algae- Phaeophyta

 

 

 

 

 

 

 

 

 

Brown algae group comprise of the largest algae. They are generally brown to yellow in colour, and have chlorophyll c and fucoxanthin as photosynthetic pigments.

 

Examples include Sargassum spp.

 

 

The Red Algae- Rhodophyta

 

 

 

 

 

 

 

 

 

The photosynthetic pigment, phycoerythrin gives these algae there characteristic coloration. These algae are capable of living at greater depths than the other two groups as they can absorb blue light for photosynthesis. Some red algae have less phycoerythrin and therefore may appear green or blue. 

 

Examples include Peysonnelia spp.

 

 

The Green Algae- Chlorophyta

 

 

 

 

 

 

 

 

 

 

These algae contain the photosynthetic pigments, chlorophyll a and b in the same proportions as in higher plants. These algae may be unicellular, multicellular and colonial.

 

Examples include Ulva spp.