Why is "VOLVOX" not considered to be in PROTOZA?

Question

Volovox is an Algae, but it moves with the help of Flagella. Protozoa has members that move by Flagella. Why is Volovox taxonomically in the Algae instead of Protozoa?

Answer 1

Volvox can actually be considered both an algae and a protozoan.

A key thing about protozoa is it is not a monophyletic group. To be considered a protozoan, an organism just has to be a single-celled eukaryote that is not a plant, animal, or fungus (as algae, Volvox is not a land plant and can still be considered a protozoan). So you can have protozoans all over the tree of life.

What makes Volvox an algae in addition to a protozoan?

1) It uses chlorophylls and other pigments for photosynthesis

2) It stores starch inside plastids

3) It has a cellulose cell wall

4) It has a flagellum structure characteristic of green algae

5) Its genetic information is more similar to green algae than other clades