Protozoa Animal-like protists

A Brief History Oldest protist fossil Oldest protist fossil –1.5 billion years old –Larger than bacteria –Membrane-bound structures All modern protist phyla present during Cambrian Period All modern protist phyla present during Cambrian Period

Organizing 6 Polyphyletic super groups of protists 6 Polyphyletic super groups of protists 4 super groups contain protozoa 4 super groups contain protozoa –Animal-like –Heterotrophic

A little vocab Protozoa – chemoorganotrophic protists Protozoa – chemoorganotrophic protists Protozoologists – study protozoans Protozoologists – study protozoans Protozoan – “first animal” Protozoan – “first animal”

Protozoan Characteristics Complete organism in a single plasma membrane Complete organism in a single plasma membrane No cell wall No cell wall Eukaryotic organization Eukaryotic organization Simple to complex colonies Simple to complex colonies

Maintaining homeostasis Pellicle Pellicle –microtubules beneath plasma membrane –maintains shape but is flexible Cytoplasm Cytoplasm –Ectoplasm – just beneath pellicle, clear & firm –Endoplasm – granular and more fluid

Maintaining homeostasis Marine: outside = inside Marine: outside = inside Freshwater Freshwater –maintain concentrations through osmosis –Contractile vacuoles

Maintaining homeostasis Eating Eating –Active transport –Endocytosis –Mouth-like cytopharynx Digestion Digestion –food vacuoles –Enzymes and acidity changes

Maintaining homeostasis Gas exchange Gas exchange –Acquiring O 2 and expelling CO 2 –Diffusion Excretion Excretion –Expelling N-based wastes (ammonia) –Diffusion

Reproduction Asexual Asexual –Binary fission –Budding –Multiple fission (schizogony)

Reproduction Sexual Sexual –Mature protozoa are haploid –Form gametes through mitosis –Meiosis follows union of gametes

Symbiotic lifestyles Symbiosis – close relation w/another organism Symbiosis – close relation w/another organism –Parasitism – live in or on host, hurting host Definitive host – harbors sexual stages Definitive host – harbors sexual stages Intermediate host – asexually reproducing offspring Intermediate host – asexually reproducing offspring –Commensalism – 1 helped, 1 neutral –Mutualism – both helped

Assignment Name of Group Name of Group –Habitat –Feeding –Movement –Reproduction –Interaction w/humans