Protozoans

 

1) Protozoa Phyla: members Protista kingdom Protozoa are united by a "negative" characteristic not multicellular; not considered members of animal kingdom.

2) Kingdom Protista : unicellular animal-like organisms.

3) Animal-like characteristics of Protozoa

a) Unicellular (negative) are not true animals (zygotes of animals are).

b) Microscope (actually a lot of multicellular, true animals).

c) Lots of diversity regard shape and symmetry.

d) Some actually have reproductive, subcellular structures, even though no true germ line or sex cells (gametes are absent but different, reproductive "forms" are present in some spp. of protozoa.

e) No true organs, but do have sub-cellular organ-like structures called organelles; lots of specialization with regard to these organelles. Cellular-grade levels of organization.

f) Change form free living, unicellular forms to colonial forms which are no truly multicellular but do show some division of labor which makes them appear and function as though multicellular; to symbiotic forms that require a host organism to complete the life cycle.

g) Motile (move by specialized structures or by changing their cellular shape.) Some are non-motile (sessile).

h) Some have specialized endoskeleton (cytoskeleton of all cells) and exoskeleton (shells -tests- inorganic material.)

i) Nutritionally - ingestive (actively taking in food & digestive food particles) and/or adsorptive heterotrophs (passively taking food insoluble form).

j) Aquatic and terrestrial spp. of protozoa.

k) Both asexual and sexual modes of reproduction.

 

Classification: Seven different phyla of protozoa

1) Sarcomastigophoros - motile by flagella and organelles protozoa (specialized structure motility) and amoeba (motile by changing cellular shape - pseudopodia foot "false cellular protrusion). Sarco-skin; masti-flagella; phoros-bearing.

2) Internal structure - nucleus of genetic material (DNA-genus-chromosomes) cytoplasm of organelles, cytoskeleton, anchors for extracellular structures vesicles and vacuoles-storage &/or digestive (even some excretory structures).

3) Nutrition - specialized structures for food uptake in the ingestive heterotrophs.

1) intake food particles through specialized opening in flagellates-oral groove.

2) in amoeba-pseudopodia will extend and surround food particles &/or bacteria or small protozoa and form a phagosome. Pha-"eat"; some-internal body structure.

3) removal solid waste products: by the cytoproct.

4) Reproduction:

a) asexual : fission -mitosis and cytokinesis to result in clones (identical daughter cells).

b) sexual: conjugation-exchange of genetic material (DNA) followed by recombination and formation of a new genetically distinct daughter cell.

Amoeba spp. - technical genus name

4) Extracellular Locomotion

a) pseudopodia of socodines (amoeba)-common name.

b) flagella : extracellular structures of flagellates; composed of long, whip-like fibers of tubulin (protein subunit of flagella), usually only one or two flagella or cell.

 

Phylum Ciliophora - ciliated protozoa such as ciliated structures (cilia) EX: Paramecium spp.

1) Extracellularly: Locomotion by cilia-short extracellular structures used for movement; many cilia present on entire external surface of organism-also create currents in aqueous media which bring food particles (small organisms) to "oral groove" for ingestion of food material.

Protozoa = "1st animal". 1st or primitive (simple).