Phylum Protozoa
What are Protozoa?
The
protozoa (proto=first, zoa=animals). Protozoa are the oldest known group of
heterotrophic life-that consume and transforms complex food particles into
energy. Although protozoans are only made up of a single cell these organisms
manage to perform all the basic tasks of life.
What do they eat?
Protozoa
eat some bacteria from the human body and sometimes harm us. Protozoa also eat
fungi and other protozoa. Protozoa mainly feed on bacteria, but they also eat
other protozoa, and sometimes fungi. Some protozoa absorb food through their
cell tissues. Others, surround food and engulf it. Others have openings called
mouth pores into which they sweep food. All protozoa digest their food in
stomach-like compartments. As they digest, they make and give off nitrogen,
which is an element that plants and other higher creatures can use.
How do they reproduce?
Many protozoans
reproduce both asexually and sexually during their lifetime. The move to sex is
often either controlled by an internal clock or by the arrival of harsh
environmental conditions. The majority of protozoans reproduce asexually by
binary fission. However, some are endosymbionts (species that live within
another organism) often engage in multiple fission with many tiny cells
produced from a single parent cell released to search out a new host. Sexual
reproduction is common in ciliates, but rare in heliozoans and amoebas, and
absent in flagellates. The three basic types of sex are gametogamy, autogamy,
and conjugation—all of which are explained on the reproduction strategies page.
Ciliates reproduce sexually through conjugation which involves the exchange of
haploid nuclei between two joined protists. Once the genetic information is
exchanged each of the ex-conjugants clones itself. These resulting daughter
cells go through a long period of "sexual immaturity" where they will
only reproduce asexually.
Where do they live?
They live in
a wide variety of moist habitats including fresh water, marine environments and
the soil.
What are the general Characteristics
of Protozoa?
- With the exception of crysts,
all are confined to watery or moist places
- Single-celled or acellular
organisms which combine normal cellular functions with those like food
capture, locomotion, etc. for which higher organisms possess special
tissuses or organs.
- Lack tissue and organs
- The functionally differentiated
parts are the organelles.
- A periode of encystment is
commonly part of the life-cycle.
What are the groups or type of Protozoa?
The four
groups of Protozoa are Amoebas, Ciliates, Flagella and Sporozoans. They differ
in theis size and their shape and the way they move and feed.
What
the examples of Phylum Protozoa?
- Examples
of Rhizopods
- Amoeba proteus (common amoeba)
- Entamoeba histolytica (causes
amoebic dysentery)
- Radiolarians (internal
glass-like skeletons)
- Foraminifera (large shelled amoeboid belonging to Sarcodina)
- Examples
of Flagellates
- Trypanosoma gambiense (sleeping
sickness)
- Trichonympha
- Examples of Ciliates
- Paramecuim
(Paramecium caudatum)
- Stentor (Stentor coeruleus)
- Examples
of Sporozoans
- Plasmodium vivax (Causes Malaria)
- Monocystis agilis
