The Seventh Kingdom: Chromista
By 1981, Cavalier-Smith had divided the domain Eukaryota into nine kingdoms. By 1993, he reduced the total number of eukaryote kingdoms to six. He also classified the domains Eubacteria and Archaebacteria as kingdoms, adding up to a total of eight kingdoms of life:
- Plantae,
- Animalia,
- Protozoa,
- Fungi,
- Eubacteria,
- Archaebacteria,
- Chromista, and
- Archezoa.
Cavalier-Smith's new classification scheme retained the plant, animal and fungal kingdoms from the traditional five kingdom model. It also split the kingdom Monera into the two groups, eubacteria and archaebacteria, as proposed by Woese and Fox. In addition it split the kingdom protists into three new kingdoms: archezoa, protozoa, and chromista.
Most chromists are photosynthetic. This distinguishes them from most other protists. In both plants and chromists photosynthesis takes place in chloroplasts. In plants, however, the chloroplasts are located in the cytosol while in chromists the chloroplasts are located in the lumen of their rough endoplasmic reticulum. This distinguishes chromists from plants.
Read more about this topic: Thomas Cavalier-Smith, Classification of Life
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