Protists Domain: Eukarya • Protists are singled cell organisms like Chapter 20 bacteria and archaea. But they are EUKARYOTIC organisms. • Classifications are still difficult due to the huge variations of traits in Protista. “Kingdom” Protista “Kingdom” Protista • Protists are “any eukaryote that is not a • Most protists reproduce plant, animal or fungus.” by simple cell division Most are single cells, or colonies of a single cell (mitosis) type… • Some protists also exchange genetic material across cytoplasmic bridges “Kingdom” Protista “Kingdom” Protista • Diatoms! • Dinoflagellates Key feature: encased in silica Key feature: two whip-like flagella (glass) shells A key type of phytoplankton Some are phytoplanton Important primary producers in aquatic ecosystems Some are mutualistic symbionts within marine organisms Phytoplankton is responsible for Some cause toxic blooms that kill fish and poison >50% of all primary production seafood. on earth! One coastal species, Pseudonitzschia , produces domoic acid (a toxin) Filter-feeders concentrate toxin, making them toxic to their predators and animals higher on food web. Image courtesy of the Santa Barbara Museum of Natural History 1 “Kingdom” Protista “Kingdom” Protista • Dinoflagellates (cont.) Some cause red tides • Apicomplexans (sporozoans) Some red-tide causing dinoflagellates are highly toxic Parasitic; form • Like the diatom infectious “spores” Pseudonitzschia , render filter- feeders toxic to vertebrates. • Example: Increased temperatures increase Plasmodium the chances of red tides and their harmful impacts. Malaria is People used to avoid seafood in becoming resistant June, July and August. to traditional medications. Malaria life cycle “Kingdom” Protista • Plasmodium Gametocytes • Ciliates develop into gametes and Possess many cilia unite in mosquito (=sexual (short, hairlike reproduction) outgrowths) used for Larvae develop movement Plasmodium larvae injected into humans via mosquito saliva • Example: Paramecium Larvae reproduce asexually in humans “spores” Note how it carries out One spore millions of spores key functions of an Causes bursting of liver and red animal, even though it is blood cells not one! Some gametocytes produced Mosquito gain gametocytes by biting a host Paramecium “Kingdom” Protista • Contractile vacuole : • Ciliates control of water balance Some ciliates prey on other ciliates! kidney-like • Oral groove and food vacuole : food intake, digestion 2 “Kingdom” Protista “Kingdom” Protista • Slime molds • Euglenoids Key decomposers • Example: Euglena Dry conditions/lack of food development of “fruiting bodies” that produce spores No cell wall; Spores disperse; some will end up in favorable conditions highly motile • Has plant & animal characteristics. euglenoids Zooflagellates • Zoo- => animal like • Use flagellum for movement • Flagellum used for propulsion and/or food • Many are photosynthetic capture Note chloroplasts Giardia : • Notice “eyespot” for causes intestinal disorders detecting light direction Found in unfiltered freshwater Affects 2.5 million people each year in the US Trypanosoma “Kingdom” Protista • Causes African sleeping sickness • Brown algae Transmitted by tse-tse flies Infects blood Algae superficially resemble plants, but lack Will lead to death if untreated key plant features. One symptom is excessive daytime sleeping; also causes other physical/neurological problems Brown color: Pigments No vaccine that absorb colors of light Treatment in later stages not always successful that penetrate water (green/blue) Chlorophyll reflects green! Example: giant kelp! Entire ecosystem thrives due to giant kelp. 3 “Kingdom” Protista Edible Red Algae • Red algae • Nori Multicellular Used as wraps in Multiple cell types sushi. Red color: Like brown algae, have pigments that absorb colors of light that penetrate water (i.e. green/blue) More effective than chlorophyll or pigments in brown algae at • Agar absorbing green/blue light Delicacy in the Can be found relatively deep Philipines and Japan in ocean “Kingdom” Protista “Kingdom” Protista • Green algae • Some Protista move with Contain the same pseudopods photosynthetic pigments as Flexible plasma plants No additional pigments for membranes allow better absorption through extension of cell in all water directions Found in shallow water Amoebas Some are multicellular Heliozoans (unusual for Protista) Forminifera & Radiolaria Some green algae are ancestors to Kingdom – Construct elaborate “shells” Plantae 4.