“Animal-Like” Protists: Protozoans

“Animal-like” Protists: Protozoans Kingdom Protista Four phyla of “animal-like” protists differentiated by locomotion All heterotrophs Protists that live primarily by ingesting food are called protozoans.

Phylum Zoomastigina - Flagellates Move by flagella – long, whip-like structures Absorb food through cell membranes No shell Some free-living, some parasites Most reproduce asexually by binary fission = genetically identical. Some reproduce sexually as well – gametes formed by meiosis = new combination of genetic information.

Phylum Sarcodina - Sarcodines Best known sarcodina is amoeba Move and feed by use of pseudopods – temporary projections of cytoplasm No body shape, the “blob” Move by amoeboid movement – cytoplasm of the cell streams into the pseudopod, and the rest of the cell follows Food vacuole temporarily stores food Reproduce by binary fission

Amoeboid Movement

Amoeba Anatomy Food vacuole Nucleus Contractile vacuole Pseudopods

Other Sarcodinas Heliozoans and radiolarians – these both produce shells of SiO 2 (silica) Foraminifers – produce shells of CaCO 3 (calcium carbonate), used in dating rocks and chalk

Phylum Sporozoa - Sporozoans Do not move, all are parasitic Live in worms, insects, fish, birds, and humans Very complex life cycles Reproduce by means of spores (groups of cells which invade a new host) Also known as Apicomplexans Plasmodium killing red blood cells

The Life Cycle of Plasmodium Plasmodium undergoes several stages of development in mosquito’s body Mosquito bites human, injecting saliva that contains Plasmodium sporozoites Plasmodium sporozoites Sporozoites infect liver cells Liver Infected liver cells burst, releasing Plasmodium cells that infect red blood cells Plasmodium cells Red blood cells Infected red blood cells burst, releasing Plasmodium cells; some can infect other red blood cells, and others can infect mosquitoes Anopheles mosquito bites infected human and picks up Plasmodium cells

Phylum Ciliophora – Ciliates Cilia – short, hair-like projections used in feeding and/or locomotion Found in fresh and saltwater Most are free-living Genus Paramecium one of the most studied protists

Anatomy of Typical ciliate Pellicle – “skin” Trichocysts – small, bottle-shaped structures used for defense and protection Macronucleus – daily genetic material Micronucleus – contains “reserve copy” of cell’s genes/reproduction genetic material Gullet – indentation in one side of organism to trap food Food vacuole – food storage and digestion Anal pore – excretion Contractile vacuoles – collect water and when full, contracts, pumping water out –W–Why is this necessary?

Paramecium Anatomy Anal pore Gullet Oral groove Trichocysts Lysosomes Food vacuoles Contractile vacuole Micronucleus Macronucleus Cilia

Reproduction of Ciliates Under most conditions, ciliates reproduce asexually by mitosis and binary fission – cell splits lengthwise, forming 2 genetically identical cells When placed under stress, conjugation may occur Conjugation allows for a crossover of genetic information, but in the end, the two cells are genetically the same – the two cells simply swapped half of each other’s genetic information. This does make new combinations of genes though = genetic diversity

Conjugation Macronucleus Micronucleus

Conjugation Macronucleus Micronucleus

Conjugation Macronucleus Micronucleus

Conjugation Macronucleus Micronucleus

“Animal-like” Protists and Disease Sporozoans – Plasmodium – malaria, Toxoplasma – damages nervous system Zoomastigina – Trypanosoma – African sleeping sickness Sarcodina – Entamoeba – amebic dysentery

Ecology of “Animal-like” Protists – Helpful Serve as food at the base of the food chain Trichonympha – live inside termites and help break down cellulose in wood for termites to then digest