PHAEOPHYCEAE: Diversity and Systematics! @12 Orders based on! • Thallus organization: haplostichous vs. polistichous! • Growth mode: diffuse vs. meristematic! • Sexual reproduction: Iso-, aniso- or oogamy! • Life history: Isomorphic, Heteromorphic or monophasic! ORDER ECTOCARPALES! Thallus type: Uniseriate branched filaments! Cells with one to several band-shaped plastids with a stalked pyrenoid! Growth mode: Diffuse! Life-history type: Isomorphic! Plurilocs! Unilocs! ECTOCARPALES LIFE CYCLE! A. Algae crustose: Family Ralfsiaceae" 1. Ralfsia! B. Algae in tufts: Fam. Ectocarpaceae! !Ectocarpus: plastids band shape! Ralfsia! Ectocarpus! C. Algae ribbonlike, cylindrical and hollow or solid, or saccate: Fam. Scytosiphonaceae ! Petalonia, bladelike & solid" Scytosiphon, unbranched tubular " Hydroclathrus, perforated " Colpomenia, globose & hollow" Rosenvingea, branched cylindrical! Petalonia! Scytosiphon! ORDER SPHACELARIALES! Family Sphacelariaceae" Thallus type: Multiseriate filaments! Sphacelaria! Growth mode: Apical cell! Sexual reproduction: " !Iso-, aniso- or oogamy! Life-history type: Isomorphic! Epiphytic! Propagules! ORDER DICTYOTALES! Thallus type: Parenchymatic! Growth mode: Apical (single or !marginal)! Sexual reproduction: Oogamy! Life-history type: Isomorphic! Family Dictyotaceae! Dictyota, single apical cell" Dictyopteris, group of apical cells, with midrib" Padina, curled margin of apical cells! Dictyopteris! ORDER LAMINARIALES or KELPS! Thallus type: Small filamentous gametophyte, large parenchymatic sporophyte! Growth mode: Apical cell in gametophytes, intercalary & meristoderm in sporophytes! Sexual reproduction: Oogamy! Life-history type: Heteromorphic! Microscopic gametophytes! LARGE! sporophytes! LAMINARIALES MORPHOLOGY! Sporophyte thallus differentiated in holdfast, stipe and blade! Blades can be entire or divided in longitudinal splits. Pneumatocyst (floats) can be present in the base of the blades! Stipes can be single or branched or reduced! Holdfast are branched structures of thickened tissues known as haptera! LAMINARIALES ANATOMY! A-D: Transverse sections! A: Outer portion of stipe" me=meristoderm" cor=cortex" se=secretory cells" md=mucilage ducts! B: Inner portion of stipe" sc=sieve cells" fm=filamentous medulla" spl=sieve plate! C: Epidermis with meristoderm! D: Sieve plate! E-F: Longitudinal sections! E: Outer cortex with pitted cells! F: Filamentous medulla! LAMINARIALES LIFE CYCLE! LAMINARIALES DIVERSITY! Laminariaceae: stipe simple Laminaria and Agarum! LAMINARIALES DIVERSITY! Macrocystis" Nereocystis" Pelagophycus" Postelsia" Giant kelp! Bull kelp! Elkhorn kelp! Sea palm kelp! LAMINARIALES DIVERSITY! Egregia" Feather boa kelp! ORDER FUCALES! Thallus type: Parenchymatic! Growth mode: Apical cell! Sexual reproduction: Oogamy! Life-history type: Monophasic, diploid, gametic meiosis! FUCALES LIFE CYCLE! FUCALES DIVERSITY! Fucaceae, branching dichotomous Fucus! Fucus " Rockweed! FUCALES DIVERSITY! Fucaceae, branching dichotomous Fucus! Sargassaceae, branching radial and alternate Sargassum, Turbinaria! Sargassum! Turbinaria! ECOLOGY! •Marine benthic communities! •Higher diversity in colder oceans! •Dictyotales is common in tropical waters! •Submarine kelp forests have similar ecological role to that of trees in terrestrial forest! •Sargasso sea with S. fluitans and S. natans and a unique community of fishes and invertebrates! •Laminaria (kombu) and Undaria (wakame) are cultivated for food! •Kelps (Macrocystis) are harvested off US West Coast for alginates extraction! THE BIG FOUR FOR STRAMENOPILES" ! Pigments: Chlorophylls a & c, and diverse xanthophylls! Storage products: Chrysolaminarin, laminarin, lipids! Cell wall: Naked, silica/organic scales; cellulose, !alginates! Flagella: Heterokonts with tripartite hairs!.