Transcript Paramecium
Kingdom Protista Kingdom Protista • Kingdom Protista - 65,000-200,000 species (est.), fr. Greek protos = first, ktistos = established - algae, protozoans • Also called Kingdom Protoctista • Taxonomic “grab bag”, primitive organisms only distantly related (polyphyletic) Kingdom Protista • All protists are eukaryotes • All protists are aquatic • Unicellular or multicellular • Some are colonial - cells specialize in different function (feeding, reproduction) = division of labor, communication Kingdom Protista • Some are autotrophs = algae • Some are heterotrophs = protozoa • Reproduce either sexually or asexually (by binary fission) • Complex life cycles Kingdom Protista • Protists are so small they don’t need special organs to exchange gas or excrete wastes • They rely on diffusion - passive movement of molecules from area of higher concentration to area of lower concentration • Diffusion results from the random movement of molecules Kingdom Protista • Diffusion is a two edged sword • Protists don’t need to invest in complex respiratory or excretory tissue • They have to stay tiny - diffusion only works if you’re very small • Most protists are single cells Kingdom Protista • Size is also limited by means of locomotion • Many protists are propelled by cilia or flagella, tiny movable hairs • Protists eat by phagocytosis > Engulf food in cell membrane > Pinch off membrane to form a vacuole > Vacuoles store food, water, enzymes, wastes Phagocytosis Didinium devours Paramecium Kingdom Protista • All of these traits are primitive - similarities may be due to convergent evolution • Protists are mainly defined by what they are not > Not bacteria, archaea, or fungi… > Not plants or animals… Kingdom Protista • Protists gave rise to all other plants and animals • Phylogeny of protists still a real mess • We assume they rose from certain groups of archaeans, but which? Kingdom Protista • Protists are so different from one another, most may represent several early independent lineages of eukaryotes • First evolved ~ 1.2 billion years ago • As many as 50 phlya recognized • We’ll focus on several typical phyla Kingdom Protista • Protozoa - heterotrophs > Motile – Cilia – Ciliophora – Flagella – Dinoflagellata, Euglenozoa – Pseudopodia – Amoebozoa, Foraminifera > Non- motile - Apicomplexa • Gave rise to higher animals Kingdom Protista Phylum Euglenozoa • 800 sp. - Euglena • Plant or animal? Heterotrophs, but 1/3d are also photosynthetic • May have formed by endosymbiosis, engulfed green algae cell Euglena Euglena Kingdom Protista Phylum Dinoflagellata • Dinoflagellates - 3,000 species, fr. Greek dinos = whirling, Latin flagellum = whip Ceratium, Gonyaulax • About half are photosynthetic Dinoflagellates Kingdom Protista Phylum Dinoflagellata • Two flagella, one like a belt, one like a tail • Many have armor of cellulose plates encrusted with silica Dinoflagellates Kingdom Protista Phylum Dinoflagellata • Importance > Zooxanthellae, dinoflagellates that have lost flagella & armor, live as symbionts in mollusks, sea anemones, jellyfish, coral > Make coral more productive, limits coral to shallow water Kingdom Protista Phylum Dinoflagellata • Importance > Algal blooms of dinoflagellates are the cause of red tide - 20 species produce potent toxins > 1987 outbreak killed half the Western Atlantic population of bottlenose dolphin! > Could make La. oysters an unforgettable experience… Red Tide 2010 Breton-Chandeleur Kingdom Protista Phylum Apicomplexa • Apicomplexa are spore-forming parasites • One end has an apical complex, apparatus designed to let them invade a host cell • Sometimes called sporozoans, many form non-motile spores Kingdom Protista Phylum Apicomplexa • Plasmodium – causes malaria • Spores are passed from one host to the next by vectors (mosquitoes etc.) • Typical parasite life cycle, with intermediate hosts Kingdom Protista Phylum Ciliophora • 8,000 species, fr. Latin cilium = eyelash, Greek phorein = to bear - Paramecium, Blepharisma • Complex little critters - many organelles and specialized structures Blepharisma Kingdom Protista • Paramecium (and many other protists) have a contractile vacuole • Complex vacuole that drains wastes from the cell Contractile Vacuole of Paramecium Kingdom Protista Phylum Ciliophora • Move by numerous cilia • Many ciliophorans defend themselves by discharging little toxic threads or darts Paramecium, with cilia stained Kingdom Protista Phylum Ameobozoa • Over 300 species – true amoeba • Move by pseudopods - extend part of cell to form a “false foot”, then flow into it (cytoplasmic streaming) • Eat other protozoans, algae, even tiny multicellular creatures Amoeba Kingdom Protista Phylum Ameobozoa • Many amoeba are parasites > Entamoeba histolyca - amoebic dysentery, infects ~10 million Americans, 50% of population in the tropics Kingdom Protista Phylum Ameobozoa • Many amoeba are parasites > Primary Ameobic Meningoencephalitis (PAM) Naegleria fowleri enters the nostrils (frequently during swimming), attacks the brain, can be fatal within one week of symptoms > PAM is relatively rare -120 U.S. cases in 25 years Kingdom Protista Phylum Ameobozoa • PAM cases include two people in La. in 2011 who died from nasal irrigation with infected water (has to go way up the nose) • PAM killed a 4 year old child in LA in 2013 who got it from playing on a Slip ‘n Slide • Later found in the municipal water supply in Arabi and Violet (a first) – easily killed by chlorination Kingdom Protista Phylum Foraminifera • Foraminifera > Marine forms, sculpted shells (calcium carbonate) > Extend cytoplasmic podia out along the spines > Spines function in feeding, swimming Kingdom Protista Phylum Foraminifera • Importance > So abundant, they formed most of the world’s limestone, marble, and chalk > Great Pyramids composed of billions upon billions of foraminiferan shells > Abundant in fossil record, used by geologists to help identify layers of rock - indicator species Foraminiferan shells Great Pyramids of Egypt Kingdom Protista • Algae – autotrophic protists > Photosynthetic > Many referred to as “seaweeds” > Gave rise to higher plants • Phaeophyta, Bacillariophyta, Rhodophyta, Chlorophyta Brown Algae - Fucus - rockweed Kingdom Protista Phylum Phaeophyta • Brown algae - 1,500 species, fr. Greek phaios = brown - Fucus, Sargassum, kelp • Mostly marine Kelp Kingdom Protista Phylum Phaeophyta • Largest protists, kelp up to 100 meters long • Blades lack conducting tissue, rely on diffusion - can be large but must be thin Brown Algae - Kelp Brown Algae - Saccorhiza polyschides Kingdom Protista Phylum Phaeophyta • Importance > Kelp forms the basis for major ecosystem along the Pacific Coast and in other cool waters > Sargassum forms large floating mats in the Atlantic, northeast of the Caribbean, a major ecosystem - Sargasso Sea once thought to trap ships Kelp Kingdom Protista Phylum Baccilariophyta • Diatoms - 11,500 species • Golden-brown pigment Kingdom Protista Phylum Baccilariophyta • Abundant in freshwater and marine habitats • Shells made of organic compounds impregnated with silica (CD jewel case) Kingdom Protista Phylum Baccilariophyta • Importance > So abundant they account for a large percentage of the oxygen added to the atmosphere > Shells form deposits called diatomaceous earth, used in abrasives, talc, and chalks > Lompoc CA quarry - 270,000 metric tons/year, Santa Monica bed is over 900 meters thick! Kingdom Protista Phylum Rhodophyta • Red algae - 4,000 species, fr. Greek rhodos = red - Polysiphonia, Nemalion • Mostly marine, closely related to green algae • Red algae dominate in salt water, green algae dominate in fresh water • Elaborate life cycles Kingdom Protista Phylum Rhodophyta • Red algae plastids (rhodoplasts) similar to certain cyanobacteria, acquired through endosymbiosis • Brown algae formed in similar fashion, eukaryotic protist swallowed a red algae Red Algae - Scinaia furcellata Kingdom Protista Phylum Rhodophyta • Importance > Agar from cell walls used for culture plates > Carrageen, thickening agent also extracted from red algae, used in making ice cream, lunch meats, cosmetics, paint, beer and wine! Kingdom Protista Phylum Chlorophyta • Green algae - ancestral to land plants • Recently recognized as sister taxon to land plants • Now “bumped up” to Kingdom Viridiplantae (algae + land plants) Chlorophyta