Phylum: protozoa
March 12, 2018
- First animals, solitary or colonial and protoplasmic grade of organization.
- Simple, unicellular microscopic organisms.
- Generally free living found in fresh water, salt water and damp soil.
- Some are parasitic and commensal.
- Body is naked or covered by pellicle, exoskeleton or internal skeleton may be present in some forms.
- Locomotory organs are pseudopodia, whip-like flagella and hair like cilia in some forms and absent in sporozoa.
- Protoplasm divided as ectoplasm and inner endoplasm.
- Nutrition is holophytic, holozoic and parasitic.
- Digestion is intracellular and occurs in food vacuoles.
- Respiration by diffusion through general body surface.
Image source: byjus
- Excretion by general body surface, temporary opening in the ectoplasm, permanent opening called cytopyge or contractile vacuoles.
- Reproduce asexually as well as sexually.
- Sexual reproduction by conjugation of adults (hologamy), or by fusion of gametes (syngamy).
- Life cycle complicated with alternation of generation.
- Resistant cysts formation under unfavourable condition and also for dispersal.
They are classified into four sub-phylum. They are:
Image source: thebiologynotes
Sub-phylum: Sarcomastigophora
- Presence of both flagella and pseudopodia for locomotion.
- Only one type of nucleus (monomorphic).
- No spore formation.
- Sexual reproduction by syngamy.
- It includes three super classes.
- Examples: Euglena, Ceratium, Trypanosoma, etc.
Sub-phylum: Sporozoa
- Locomotory organs are absent in adult stage.
- All are parasitic.
- Cilia or flagella may be present in gametes.
- Sexual reproduction occurs by syngamy.
- The spores are simple and contain one to many sporozoites.
- The sporozoites are infective phase.
- The nucleus is only one type.
- It includes three classes.
- Examples: Plasmodium, Nematocystis, Toxoplasma, Sarcocystis, etc.
Image source: thebiologynotes
Sub-phylum: Cnidospora
- Spores are multicellular.
- All members are parasitic in cold blooded vertebrates and in invertebrates.
- Zygotes give rise to one or more trophozoids without sporogony.
- It includes two classes.
- Examples: Ceratomyxa, Nosema, etc.
Sub-phylum: Ciliophora
- Have rows of cilia.
- Unique nuclear dimorphism i.e two types of nuclei are present.
- Nuclei are micronucleus and macronucleus.
- Possess a cell mouth or cytostome.
- Specialized superficial zone of cytoplasm is called pellicle.
- It includes only one class.
- Examples: Paramecium, Coleps, Colpidium, etc.
References:
i) https://www.ncbi.nlm.nih.gov/books/NBK8325/