ALGAE

Seaweed, easily confuse with seagrass (photo by Selma P.)

The word algae represents are large group of different organisms from different photosynthetic groups, representing many taxonomic divisions. In general algae can be referred to as plant-like organisms that are usually photosynthetic and aquatic, but do not have true roots, stems, leaves, vascular tissue and have simple reproductive structures. They are distributed world wide in the sea, in freshwater and in water waste. Most are microscopic, but some are quite large, example, some marine seaweeds that can exceed 50 m in length.

Seaweeds include members of the red, green and brown algae. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in land plants. For that reason they are currently excluded from being considered plants.
The green algae are the most diverse group of algae, with more than 7 000 species growing in variety of habitats. The green algae are a paraphyletic group because it excludes the plantae. Like the plants the green algae contains two types of chlorophyll, which they use to capture light energy to fuel the manufacture of sugars, but unlike plants they are primarily aquatic.

Seaweed (Photo by Selma P.)

Red algae are red because of the presence of the pigment phycoerythrin; this pigment reflects red light and absorbs blue light. Because blue light penetrates water to a greater depth than light of longer wavelengths, these pigments allow red algae to photosynthesize and live at somewhat greater depths than most other "algae". Some rhodophytes have very little phycoerythrin, and may appear green or bluish from the chlorophyll and other pigments present in them.
Some rhodophytes are also important in the formation of tropical reefs, an activity with which they have been involved for millions of years; in some Pacific atolls, red algae have contributed far more to reef structure than other organisms, even more than corals. These reef-building rhodophytes are called coralline algae, because they secrete a hard shell of carbonate around themselves, in much the same way that corals do.

Algae are an extremely important species. For one, they produce more oxygen than all the plants in the world, put together! For another, they form an important food source for many animals such as little shrimps and huge whales. Thus, they are at the bottom of the food chain with many living things depending upon them.
With the recent research and interest into using algae for producing bio-diesel, they have the potential to become even more important. So everything that seems useless has its values.


Different types of Seaweeds (Photo by Selma P.)