Protozoan means first animal. There are 65,00 species - many of which are parasites. Protozoans are grouped according to their means of locomotion. None are photosythetic. Flagellated There are free living and parasitic forms.
Cysts contaminate the water supply.
Amoeboid All use a pseudopod for locomotion or for feeding. Sporozoan All are parasites. They have a spore-like stage in the life cycle. Many need vectors to transmit the spores to the host during part of the life cycle. Plasmodium - Four of this group cause malaria in humans and birds.