Protists II: Algae and Fungus-like Protists

Algae

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.