World Builders™
World Builders™
Session Five  --  Seaweeds
Session Five  --  Seaweeds


The Eukayrotes have been divided into Four Kingdoms:  Protists, Fungi, Plants and Animals.

   When eukaryotic cells evolved, their size, use of oxygen, and their complexity suddenly opened a whole universe of possibilities to them.  What could they become?

     There must have been a time of experiments -- eukaryotes that were a little different from their parents, that metabolized a little differently, that moved or gathered energy in ways not seen before.  However, as in all experimental ventures, we can guess that not all these organisms flourished: many probably died and simply disappeared a long time ago.  However, many of these organisms are still with us, and they have been gathered together into a kingdom called the Protists.  The experimentation is still going on!

     Scientists are studying the protists, and the more they study them, the more different groups of protists they find.  They are amazing varied.  Scientists are examining the DNA of these organisms and figuring out how the different groups are related.  Much of what we learn about them now will probably be refined and modified in the years ahead.

    We can only see the organisms that still survive today. The protists are eukaryotes, so they have nuclei in their cells, and many of them are single celled organisms.  Some have plant-like characteristics, some animal-like characteristics, some are fungi-like and others do not fit into any of these groups.  It is believed that animals, plants, and fungi evolved from protists.  We will look at a few characteristics of the protists and the plants, animals, and fungi that evolved from them.  

    At this part of the course, we are looking for the larger life forms that would be immediately obvious to us as we explore the world that we are discovering.  All of them are descended from protists, and in this lesson we are looking at the algae, who are still classified as protists.  Later, as the algae evolve into land plants, they will have their own kingdom.

    When we read about microbiology, we learned that there are three domains: Eukaryotes, Archaea, and Bacteria

     Now we are moving up to the next level:  the Five Kingdoms.  Here they are listed

Three Domains Five Kingdoms  Comments
Eukaryotes Protists

Plants --------------
Fungi ---------------
Animals -----------

These three kingdoms evolved from Protists but are sufficiently distinctive and robust to be kingdoms themselves now

Monera            (Includes all Prokaryotes)

Study Tip:  I know that this naming of domains and kingdoms is rather confusing, but the confusion represents our human process of trying to understand the natural world.  Do not worry about it -- the scientists are working on making sense of what they are finding out, and the listing will be clarified when more is known..

The natural world is comprehensible and coherent.  It does make sense -- all the way.  When you are studying it you should try and make sense of what you learn, and to find examples or experiences that tie the knowledge to what is in your mind already.  When you glimpse the beauty of the Big Picture it will take your breath away!

However, there are times when you should just shut your eyes and memorize.  These naming conventions should be memorized, as they will help you to make sense of what you will be learning soon.  They make sense in part.  As persons and as a species we have much to learn, and the joy of discovery is out there -- Boldly go!

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© 1996,1997, 1998, 1999, 2000, 2002, 2003.   Elizabeth Anne Viau. All rights reserved. This material may be used by individuals for instructional purposes but not sold. Please inform the author if you use it at .