Furthermore the book divides all these kingdoms into many phyla. Humans belong to the phylum Chordata. Rotifers that are also animals have their own phylum Rotifera. More about this subject can be read in David Goldstein's Micscape article Classification of Living Things . Scientists decided to use the term Protoctist instead of Protist since protist was always used for single celled creatures.
Several Protoctists are multi-celled or large.
I n our identification kit we often use the term 'green algae'. But many organisms that look very similar to these green algae are put in other phyla, like desmids and the Spirogyra-like filamentous algae. These are both placed in the phylum Gamophyta, the 'conjugating green algae'. We did not mention Phyla like Cryptophyta, Chrysophyta or Xanthophyta since they are difficult to keep apart. Scientists are still making new classifications as well.