Kingdom Protista Chapter 18

Outline Introduction Features of Kingdom Protista Algae Phylum Chlorophyta – The Green Algae Phylum Chromophyta – The Yellow-Green Algae, Golden- Brown Algae, Diatoms, and Brown Algae Phylum Rhodophyta – The Red Algae Phylum Euglenophyta – The Euglenoids Phylum Dinophyta – The Dinoflagellates Phylum Cryptophyta – The Cryptomonads Phylum Prymnesiophyta (Haptophyta) – The Haptophytes Phylum Charophyta – The Stoneworts Human and Ecological Relevance of the Algae

Outline cont’d. Phylum Myxomycota – The Plasmodial Slime Molds Phylum Dictyosteliomycota – The Cellular Slime Molds Phylum Oomycota – The Water Molds

Introduction < 1 bya, organisms confined to oceans Protected from drying out, UV radiation, and large fluctuations in temperature Absorbed nutrients directly from H2O Ca. 400 mya, green algae began making transition from H2O to land Gave rise to green plants Coleochaete probably indirect ancestor of land plants Shares features with land plants: parenchyma-like cells, cell plate and phragmoplast during mitosis, protective covering for zygote, and production of lignin-like compound Coleochaete

Features of Kingdom Protista Domain Eukarya - all members have eukaryotic cells Includes Kingdoms Protista, Plantae, Fungi, Animalia Organisms in Protista diverse and heterogeneous Nutrition varied: photosynthetic, ingestion of food, absorption of food Individual life cycles vary considerably Reproduction generally by cell division and sexual processes Algae in Kingdom Protista Grouped into several phyla based on form of reproductive cells, and combinations of pigments and food reserves

Phylum Chlorophyta Green Algae Unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves Greatest variety in freshwater lakes, ponds, and streams Have chlorophylls a and b Store food as starch Most have single nucleus per cell Most reproduce both sexually and asexually

Phylum Chlorophyta Chlamydomonas Common in freshwater pools Unicellular Pair of whip-like flagella 2 or more vacuoles at base of flagella Regulate H2O content of cell and remove waste Single, cup-shaped chloroplast with 1 or 2 pyrenoids inside Pyrenoids - proteinaceous structures associated with synthesis of starch Red eyespot near base of flagella Allows alga to swim toward light

Phylum Chlorophyta Chlamydomonas

Phylum Chlorophyta Chlamydomonas asexual reproduction: Nucleus divides by mitosis, and cell contents become 2 daughter cells within cellulose wall Each develop flagella and swim away No change in chromosome number; all cells 1n

Phylum Chlorophyta Chlamydomonas sexual reproduction:

Phylum Chlorophyta Ulothrix Filamentous with holdfast cell at one end Single, wide, curved, somewhat flattened chloroplast, with 1-several pyrenoids

Phylum Chlorophyta Spirogyra (watersilk) Filaments of cylindrical cells Frequently floats in masses on surface of quiet freshwater Chloroplast ribbon-shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals Asexual reproduction by fragmentation of filament

Phylum Chlorophyta Spirogyra (watersilk) cont’d. Sexual reproduction by conjugation

Phylum Chlorophyta Oedogonium Epiphytic filamentous green alga with holdfast Large netlike chloroplast with pyrenoids at intersections of net Asexual reproduction by fragmentation or by zoospores Zoospores produced singly in cells at tips of filaments and have ca. 120 flagella forming fringe at one end Sexual reproduction by oogamy - 1 gamete motile and other stationary and large

Phylum Chlorophyta Oedogonium sexual reproduction

Phylum Chlorophyta Other green algae Chlorella - widespread green alga composed of tiny spherical cells Only reproduce asexually by forming either daughter cells or autospores through mitosis Used in research; may become important as food source Desmids - mostly free-floating and unicellular Reproduce by conjugation Closterium, a desmid

Phylum Chlorophyta Other green algae cont’d. Hydrodictyon (water nets) - net-like, tubular colonies with hexagonal or polygonal meshes Asexual reproduction and isogamous sexual reproduction Isogamous - 2 flagellated gametes

Phylum Chlorophyta Other green algae cont’d. Acetabularia (mermaid’s wineglass) - consists of single, huge cell shaped like delicate mushroom Used in classic experiments demonstrating influence of nucleus on form of cell Isogamous sexual reproduction

Phylum Chlorophyta Other green algae cont’d. Volvox - colonial green algae held together in secretion of gelatinous material, resembling hollow ball Reproduction asexual or sexual Smaller daughter colonies formed inside parent colony

Phylum Chlorophyta Other green algae cont’d. Ulva (sea lettuce) - multicellular seaweed with flattened green blades and basal holdfast to anchor blades to rocks 1n and 2n blades 2n blades produce spores developing into 1n blades 1n blades bear gametangia - form gametes Zygotes grow into 2n blades 1n and 2n blades indistinguishable = isomorphic

Phylum Chromophyta Yellow-green algae (Xanthophyceae) Mostly freshwater, with few marine and terrestrial species 2 flagella of motile cells oriented in opposite directions Vaucheria - Oogamous, coenocytic, filamentous species Aplanospores formed during asexual reproduction Sexual reproduction rare Stipitococcus, a yellow-green algae Sexual reproduction in Vaucheria

Phylum Chromophyta Golden-brown algae (Chrysophyceae) Most occur in plankton of fresh H2O Motile cells have 2 flagella of unequal length inserted at right angles to each other Photoreceptor on short flagellum

Phylum Chromophyta Diatoms (Bacillariophyceae) Unicellular Fresh and salt H2O, particularly abundant in cold marine habitats Dominate algal flora on damp cliffs, tree bark or buildings Look like ornate, glass boxes with lids 95% of wall silica Chlorophylls a and c and fucoxanthin Food reserves = oil, fats or laminarin

Phylum Chromophyta Diatoms (Bacillariophyceae) cont’d.

Phylum Chromophyta Brown algae (Phaeophyceae) Relatively large; none unicellular or colonial Most marine; majority in cold, shallow H2O Many have thallus differentiated into holdfast, stipe, and blades Blades may have gas-filled bladders Chlorophylls a and c, fucoxanthin Food reserve = laminarin Algin in cell walls Nereocystis, a kelp

Phylum Chromophyta Brown algae (Phaeophyceae) cont’d. Sargassum - floating brown seaweed Asexual reproduction by fragmentation or autospores Sargassum

Phylum Chromophyta Brown algae (Phaeophyceae) Fucus (Common rockweed) Sexual reproduction

Phylum Rhodophyta Red algae In warmer and deeper waters than brown algae Most filamentous with filaments so tightly packed they appear to have flattened blades or branched segments

Phylum Rhodophyta Red algae cont’d. Relatively complex life cycle involving 3 types of thallus structures Nonmotile reproductive cells

Phylum Rhodophyta Red algae cont’d. Colors mostly due to phycobilins Similar to those of cyanobacteria Red algae may have been derived from cyanobacteria Chlorophylls a, c, and sometimes d Food reserve - Floridean starch Numbers of species produce agar

Phylum Euglenophyta Euglenoids No cell wall; pellicle = plasma membrane and underlying strips that spiral around cell Flagellum Gullet ingests food Ca. 1/3 of species have disc-shaped chloroplasts Red eyespot for light detection Paramylon food reserve Asexual reproduction by cell division. Sexual reproduction not confirmed

Phylum Dinophyta Dinoflagellates Red tides - sudden multiplication of dinoflagellates Some produce neurotoxins that accumulate in shell fish Cellulose “armor plates” inside cell membrane 2 flagella in intersecting grooves One acts as rudder Other gives cell spinning motion

Phylum Dinophyta Dinoflagellates cont’d. Most have disc-shaped chloroplasts Contain xanthophyll pigments Chlorophylls a and c Ca. 45% non-photosynthetic Chromosomes remain condensed and visible throughout life of cell Food reserve = starch Many have tiny projectiles that fire when irritated

Phylum Cryptophyta Cryptomonads Marine and freshwater 2 flagella Plates on inside of plasma membrane Single, 2-lobed chloroplast with starch granules surrounding central pyrenoid Nucleomorph - estigial nucleus of primitive symbiotic organism Gullet with ejectosomes - aid in propulsion Sexual reproduction unknown

Phylum Prymnesiophyta (Haptophyta) Haptophytes Fresh and saltwater; major component of marine plankton Most unicellular, with 2 smooth flagella of similar length inserted at apex Pigments and food reserve similar to Chromophyta Haptonema – 3rd flagellum located between 2 flagella Aids in food capture Often covered in scales 2 disc-shaped chloroplasts

Phylum Charophyta Stoneworts Shallow, freshwater lakes and ponds Often precipitate Ca salts on surfaces Axis with short lateral branches in whorls Sexual reproduction is oogamous Multicellular antheridia

Human and Ecological Relevance of Algae Protistan algal phyla at bottom of food chain Diatoms Oils sources of vitamins Diatomaceous earth Filtration Polishes, toothpaste Paint that reflects light Other algae Chlorella Potential human food source

Human and Ecological Relevance of Algae Algin Produced by giant kelps and other brown algae Ice cream, salad dressing Latex paint, textiles, ceramics Regulates H2O behavior Controls development of ice crystals Regulates penetration of water Stabilizes suspensions Vessel harvesting kelp

Human and Ecological Relevance of Algae Minerals and food Iodine from kelp Red algae Food - Dulse, nori Carrageenan - thickening agent Agar Produced by red alga Gelidium Solidifier of nutrient culture media Retains moistness in bakery products Base for cosmetics

Phylum Myxomycota Plasmodial slime molds Without chlorophyll Feed on bacteria and other organic particles Consist of plasmodium Protoplasm containing many 2n nuclei No cell wall Flows rapidly and rhythmically Found on damp forest debris, under logs, on dead organic material Plasmodium

Sporangia from various plasmodial slime molds Phylum Myxomycota Plasmodial slime molds cont’d. Sexual reproduction: Plasmodium converts into separate small sporangia containing spores Sporangia from various plasmodial slime molds

Phylum Myxomycota Plasmodial slime molds cont’d. Sexual reproduction of plasmodial slime mold:

Phylum Dictyosteliomycota Cellular slime molds Individual amoebalike cells feed independently, dividing and producing separate new cells periodically Clump together to form mass called pseudoplasmodium Crawls like a garden slug Eventually transforms into sporangium-like mass of spores Human and ecological relevance of the slime molds Break down organic particles to simpler substances

Phylum Oomycota Water molds Cottony growths on fish; often found on dead insects Range in form from single spherical cells to branching, threadlike, coenocytic hyphae Coenocytic hyphae not divided into individual cells and may form large thread masses (mycelia) Share features with brown algae, including oogamy, cellulose in cell walls, predominantly 2n lifecycle, and zoospores with 2 flagella Asexual reproduction: Crosswalls form at tips of hyphae Zoospores produced inside and emerge through pore

Phylum Oomycota Water molds cont’d. Sexual reproduction: Meiosis takes place in oogonia and antheridia Zygotes formed in oogonia give rise to new mycelia Human and ecological significance of water molds: Downy mildew on grapes Potato blight

Review Introduction Features of Kingdom Protista Algae Phylum Chlorophyta – The Green Algae Phylum Chromophyta – The Yellow-Green Algae, Golden- Brown Algae, Diatoms, and Brown Algae Phylum Rhodophyta – The Red Algae Phylum Euglenophyta – The Euglenoids Phylum Dinophyta – The Dinoflagellates Phylum Cryptophyta – The Cryptomonads Phylum Prymnesiophyta (Haptophyta) – The Haptophytes Phylum Charophyta – The Stoneworts Human and Ecological Relevance of the Algae

Review cont’d. Phylum Myxomycota – The Plasmodial Slime Molds Phylum Dictyosteliomycota – The Cellular Slime Molds Phylum Oomycota – The Water Molds