Protozoa

Protozoa

• Protozoa or Cornelius protozoans (from Greek proton "first" and zoa "animals"; singular protozoon; (the word "protozoan" is originally an adjective, used as a noun) are microorganisms classified as unicellular eukaryotes.
• All Protozoans are heterotrophs and live as predators orparasites.
• They are believed to be primitive relatives of animals.
• They may be broken down into four primary categories, which are as follows:
  • Ciliated Protozoans:
    • They are mostly Aquatic animals.
    • They are actively moving organisms because of the presence of thousands of cilia.
    • They have a cavity (gullet) that opens to the outside of the cell surface.
    • The coordinated movement of rows of cilia causes the water laden with food to be steered into the gullet. Example- Paramecium.

• Amoeboid protozoans:
• They may be found in saltwater, as well as freshwater, and wet soil.
• They have pseudopodia (false feet) which help to change their shape and to capture engulf food. E.g. Amoeba.
• Marine forms have silica shells on their surface.
• Some of them such as Entamoeba are parasites.

• Flagellated protozoans:
• As the name suggests, the members of this group have flagella.
• They can be free-living as well as parasitic.
• Trypanosoma species can spread some dangerous diseases such as sleeping sickness.

Trypanosoma

• Sporozoans:
• This includes diverse organisms that have an infectious spore-like stage in their life cycle.
• The most notorious is Plasmodium (malarial parasite) which causes malaria which has a staggering effect on human population.

Plasmodium