Kingdom Protista

Kingdom Protista - 65, ,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

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