Kingdom Protista
Main

Eubacteria / Archaebacteria

Protista

Animalia

Fungi / Plantae

Viruses

Life Cycles

General Characteristics


  • Most are singled celled; some are multicellular organisms; some are eukaryotic.
  • Some are autotrophs, some heterotrophs, some both
  • reproduce sexually and asexually
  • live in aquatic or moist habitats

 

Protista is made up of three distinct groups: plantlike protists, animal-like protists, and fungilike protists. Their Anatomical and Physiological Characteristics are seen below under each specific heading.
 

 

PLANTLIKE PROTISTS

  • contain chlorophyll
  • traditionally are called algae
  • flagellated protists reproduce asexually (longitudinal fission)
 
  • euglenids are unique 

o       they obtain nourishment by means of photosynthesis but during periods of darkness

o       become heterotrophic and take in solid food, a trait commonly associated with animals

 
  • Green Algae = Chlorophyta
  • Brown Algae = Phaeophyta (seaweed)
  • Red Algae = Rhodophyta (sea weed)

o       Algae are well adapted to wet or moist environment but can be found in soils, on the lower trunks of trees, and on rocks.

o       They are primary food producers in aquatic food chains.

o       Supply 67% of the world’s oxygen

o       Excessive algae growth can lead to a problem
 

 

ANIMAL-LIKE PROTISTS

  • All protozoa are heterotrophs
  • Most protozoa are said to be holozoic because they engulf their food.
  • Others, called zaprozoic absorb predigested or soluable nutrients directly through the cell membranes.
  • They occupy a diverse range of moist habitats
  • The classification of Protozoa is based on their type of locomotion, type of organelle, mode of reproduction, nutrition, and whether the organism is free-living or parasitic.
  • Protozoans rival bacteria in population numbers and number of species.

  • Phylem Sarcodina

o       Most sarcodines are free-living except a few species found in animal intestines.

o       Moves by repeatedly extending and retracting its pseudopods.

o       Cytoplasm has 2 layers - ectoplasm and endoplasm

o       Feeds by phagocytosis

o       Reproduces by binary fission

 
  • Phylum Masigophora

o       Have one or more flagella

o       Free living types mainly live in freshwater or marine habitats

o       Parasitic types live inside other organisms

 
  • Phylum Ciliophora 

o       Possess hairlike structures called cilia

o       Free-moving ciliates swim and other ciliates attached to a surface

o       Most advanced of protozoans

o       Inhabit freshwater and marine habitats

o       Can periodically produce sexually by conjugation

 
  • Phylum Sporozoa

o       Lack any means of independent locomotion.

o       Most have nothing except a few types have flagella while maturing.

o       Exclusively parasitic

o       Have reproductive cells which can reproduce without fertilization

o       Sometimes two or more hosts are involved, in which case the parasite reproduces sexually in one host and asexually in the other.
 

 

FUNGILIKE PROTISTS

  • A.K.A. slime moulds are placed in phylum gymnomycota
  • Prefer cool, shady, moist places and are usually found under fallen leaves or on rotting logs
  • Resemble protozoans during some stage of their life cycle and become amoebalike or have flagella
  • They produce spores much like fungi do at other times.
  • Spend some of its life cycle as a single-celled amoebalike organism but can converge into a large slimy mass plasmodium.

o       This mass acts like an organism itself

o       It extends into a slugllike form and begins to creep and feed on organic matter.

o       If it runs into an object, it retracts and slithers around it.