There are three divisions of algae, which are red, brown and green seaweeds. Rhodophyta is the latin name for the division red algae. This division contain over 6200 species of algae and 90 % lives in the ocean. Rhodophyta is evolutionary the oldest, and it is now acknowledged that these photosynthetic groups evolved independently of each other. Actually, one way of separating the these groups from each other, is looking at the number of plastid membranes. Rhodophyta has two plastid membranes, Chlorophyta (green algae) has three and Phaeophyceae (brown algae) has four. A plastid membrane is the site of manufacture and storage of important chemical compounds used by the cell.

I am a part of the class Biology of Seaweeds, which is taught in Moss Landing Marine Labs in California, where we learn about all seaweeds and make seaweed herbariums. If you are more interested in the evolution of seaweeds and other organisms, I highly recommend you to check out “Cellmates”, a podcast by Radiolab. It can be found here: http://www.radiolab.org/story/cellmates/ . They reveal that humans and seaweeds actually have many things in common! We possess the same mitochondria, which are the energy-producing sites.  We also possess the same enzyme, which is called carbonic anhydrase. This enzyme has the power to catalyze or convert carbon dioxide and water to bicarbonate and protons.

The highest diversity of seaweeds are found within the reds, and this may be because they have had the longest time to evolve. Many of them are very pretty, and Callophyllis and Prionitis are among my favorites.

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I used the foldscope and I took a picture of another red seaweed, that I actually think is prettiest when it is magnified. This is a picture of a species within the genus Polysiphonia, which has 17 species from Alaska to Baja California, and 223 species worldwide. If you look closely, you can see the box-like structure. This is a radially branched seaweed, so when it is found in the intertidal, it looks fluffy.


The red seaweeds have such a huge variety, so if you like what you see I suggest you to look more closely the next time you are in the intertidal – so you can observe and admire all the shapes, colors and sizes seaweeds can have.


Written by Therese Meyer

One Comment Add yours

  1. Manu Prakash says:

    Beautiful post Therese. I think you have an issue with Folds on your foldscope.. Could you redo all the steps – you should get sharp images. See example of kelp cells here: https://microcosmos.foldscope.com/?p=9165

    You can go through the video tutorials here: https://microcosmos.foldscope.com/?page_id=243


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