Protists II: Algae and Fungus-like Protists

Algae

• "Normative" forms are haploid, diploid forms are often restricted to a single cell.
• Diploid zygote may be adapted to surviving winter conditions, as in freshwater green algae.
• Different groups of algae differ in types of chlorophyll that cells possess. All forms possess chlorophyll a.

Common name	Phylum	Morphology	Reproduction	Example
Euglenoids	Euglenophyta	Unicellular	Asexual by longitudinal cell division; sexual reproduction has never been observed.	Euglena
Dinoflagellates	Dinoflagellata	Unicellular; some colonial	Primarily asexual, by longitudinal cell division; sexual reproduction has been observed in a few spp. Gonyaulax spp. is responsible for toxic red tides in estuarine habitats.	Gonyaulax
Diatoms	Bacillariophyta	Unicellular; some colonial	Asexual, with progressive reduction in cell size. Sexual reproduction is triggered when the cells reach a certain minimal size.	Dinobryon
Golden algae	Chrysophyta	Unicellular; some colonial	Primarily asexual, and involves the production of flagellated, motile spores called zoospores.	Synura
Brown algae	Phaeophyta	Multicellular	Reproductive cells, both asexual zoospores and sexual gametes, are usually flagellated. Most have life cycles with an alternation of generations.	Fucus
Green algae	Chlorophyta	Unicellular, coenocytic; colonial; multicellular	Both asexual and sexual reproduction occur. Many species show alternation of generations.	Spirogyra
Red algae	Rhodophyta	Most multicellular; some unicellular	Alternation of sexual and asexual generations	Botryglossum farlowianum

Fungus-like Protists

· In many species, cells spend much of the time in unicellular form;

· Environmental or other cues cause cells to merge to form a flat thallus;

· Fruiting body then emerges, and is negatively geotactic.

Common name	Phylum	Morphology	Reproduction	Example
Plasmodial slime molds	Myxomycota	Multinucleate plasmodium	Flagellated or amoeboid reproductive cells. These reproduce by spores in sporangia. Asexual and sexual phases	Physarum sp. Physarum on water surface: http://www.youtube.com/watch?v=t8OpYx0dGI8 Slime mold formation: http://www.youtube.com/watch?v=hpHpBHJZQvU&feature=related
Cellular slime molds	Acrasiomycota	Unicellular feeding stage; multicellular (slug & fruiting body)	Asexual and sexual phases.	Dictyostelium sp. Chemotaxis of a population of Dictyostelium: http://www.youtube.com/watch?v=Ql7i_TLUurM “Dicty”, in German, but you can get the gist of the development of the fruiting body: http://www.youtube.com/watch?v=VWGA7kIeE0Q&feature=related
Water molds	Oomycota	Coenocytic mycelium	Biflagellate zoospores. Asexual and sexual phases; saprobe of dead aquatic organisms, detritus; parasites of fish eggs & diseased fish.	Saprolegnia sp.