Now I'm going to move into some of the eukaryotic algae. I don't know what your background is with regards to algae but there are lots of different groups of algae and many of them are represented in the soil. Some of them are sort of surprises to us. This is not a surprise. This is a green alga, Gloeocystis. I show this picture because I want to indicate that they have this huge mucous sheath around them. They really pump out the polysaccharide. This is significant because it is this mucilage material both from cyanobacteria and from green algae that is probably instrumental in sticking the soil particles together. So the reason we get a crust on the surface of the soil and the reason the crust is biotic in origin is because of the polysaccharides these things pump out of their cells.

Here is another one that is very mucilaginous. You can tell because the cells are spaced out rather evenly. It's all mucilage in the clear interspaces. This is Palmella texensis. I wanted to point out something else about this. Many of the green algae have orange pigments in them. They are carotenoid pigments and my guess is that they also help in protecting the photosynthetic apparatus.

Mymecia is a very common soil algae that most phycologists never see. We have at least two phycologists in the audience and I thought I'd show something new for them. This is Chlorosarcinopsis. We have a whole group of green algae that have this specialized growth form (packet formation) that essentially show up only in this habitat.

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