- They are unicellular and microscopic organisms. Some are single cells while others are colonial.
- The nuclear material is not enclosed within cellular membrane hence they are said to be prokaryotic
- They have cell wall but not made up of cellulose
- They have few organelles. They are not membrane bound. Mitochondria are absent
- Most of them are heterotrophic, feeding saprophyticaly or parasitically, some are autotrophic.
- Reproduction is mostly asexual through binary fission.
- Most of them are anaerobes but some respire aerobically.
- They move by flagella.