Cavalier-Smith's Six Kingdom Models
By 1998, Cavalier-Smith had reduced the total number of kingdoms from eight to six : Animalia, Protozoa, Fungi, Plantae (including red and green algae), Chromista and Bacteria.
Five of Cavalier-Smith's kingdoms are classified as eukaryotes as shown in the following scheme:
- Eubacteria
- Neomura
- Archaebacteria
- Eukaryotes
- Kingdom Protozoa
- Unikonts (heterotrophs)
- Kingdom Animalia
- Kingdom Fungi
- Bikonts (primarily photosynthetic)
- Kingdom Plantae (including red and green algae)
- Kingdom Chromista
Eukaryotes are divided into two major groups: unikonts and bikonts. Uniciliates are cells with only one flagellum and unikonts are descended from uniciliates. Unikont cells often have only one centriole as well. Biciliate cells have two flagella and bikonts are descended from biciliates. Biciliates undergo ciliary transformation by converting a younger anterior flagellum into a dissimilar older posterior flagellum. Animals and fungi are unikonts while plants and chromista are bikonts. Some protozoa are unikonts while others are bikonts.
The Bacteria (= prokaryotes) are subdivided into Eubacteria and Archaebacteria. According to Cavalier-Smith, eubacteria is the oldest group of terrestrial organisms still living. He classifies the groups which he believes are younger (archaebacteria and eukaryotes) as neomura.
Read more about this topic: Thomas Cavalier-Smith
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