Example Organisms

Protists

Giardia intestilanis

• A diplomonad parasite that can infect people when they drink water contaminated with feces containing the cysts of the parasite. Drinking such water – even from a seemingly pristine stream – can cause severe diarrhea. Boiling the water kills the parasite.

CC image via http://abouthealt-h.com/wp-content/uploads/2011/10/Giardia-Intestinalis5.jpg

• Protists of the kinetoplastids have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast. These protists include species that feed on prokaryotes in freshwater, marine, and moist terrestrial ecosystems, as well as species that parasitze animals, plants, and other protists. One example, Trypanosoma brucei causes sleeping sickness in humans, a neurological disease that is invariably fatal if it is not treated. The trypanosomes infect humans via the bite of a carrier organism, the African tsetse fly.

Trypanosoma brucei

CC image via http://en.wikipedia.org/wiki/File:Trypanosoma_sp._PHIL_613_lores.jpg

Trichomonas vaginalis

• CC image via http://www.sciencephoto.com/image/148029/530wm/C0085110-Trichomonas_Vaginalis_SEM-SPL.jpg

• Trichomonas vaginalis is the best known parabasalid (Excavates that have reduced mitochondria and generate some energy anaerobically, releasing hydrogen gas as a by-product). T. vaginalis is a sexually transmitted parasite that infects some 5 million people every year. It moves along the mucus-coated lining of the human rproductive and urinary tracts by moving its flagella and by undulating part of its plasma membrane.

Plasmodium malariae

• CC image via http://en.wikipedia.org/wiki/File:Mature_Plasmodium_malariae_schizont_PHIL_2715_lores.jpg

• This important pathogen is part of the Chromalveolata supergroup. It is significant because it causes malaria among humans. It causes fevers of three-day intervals; hence it is commonly called quartan malaria.

Phytophthora infestens

• CC image via http://botit.botany.wisc.edu/toms_fungi/images/phy-oo.gif

• This oomycete is part of the Chromalveolata supergroup. It is known for causing a potato disease known as “late blight” which turns the stalk and stem of potato plants to black slime. Late blight contributed to the devastating potato famine in 19th century Ireland, in which millions of people died and were forced to leave Ireland.

Pfiesteria shumwayae

• CC image via http://www.vims.edu/research/departments/eaah/programs/pfiesteria_research/resources/images/index.php

• Pfiesteria shumwayae is a dinoflagellate that beats its spiral flagellum, which lies in a groove that encircles the cell, makes this alveolate spin. The dinoflagellates are characterized by cells that are reinforced by cellulose plates. Two flagella located in perpendicular grooves in this “armor” make dinoflagellates spin as they move through the water.

Globigerina falconensis

• CC image via http://skepticwonder.fieldofscience.com/2009/11/sunday-protist-assorted-forams.html

• This radiolarian’s “needles” are thin pseudopia. The pseudopia of these mostly marine protists radiate from the central body and are reinforced by bundles of microtubules. The microtubules are covered by a thin layer of cytoplasm, which engulfs smaller microorganisms that become attached to the pseudopodia. In some species, during the day, the algae are transported to the tips of the pseudopia where they can photosynthesize, and drawn back in for the night.

Postelsia palmaeformis

• CC image via http://www.botany.ubc.ca/martone/postelsia.jpg

• More commonly known as the sea palm, Postelsia palmaeformis lives on rocks along the coas of the northwestern United States and Western Canada. The term thallus refers to an algal body that is plantlike, but lacks true roots, stems, and leaves. The thallus of this brown alga is well adapted to maintaining a firm foothold despite the crashing surf.

Porphyra yezoensis

• CC image via http://en.wikipedia.org/wiki/File:Nori.jpg

• Porphyra is a multicellular red algae, commonly referred to as seaweed, in the Archaeplastida supergroup. Porphyra (Japonese “Nori”) are the paper-thin, glossy sheets used to make a mineral-rich wrap for rice, seafood, and vegetables in sushi. The harvested seaweed is spread on bamboo screens to dry into the crispy sheets.

Chlamydomonas nivalis

• CC image via http://www.nicerweb.com/bio1903/Locked/media/ch28/28_29WatermelonSnow.jpg

• The simplest chlorophytes of green algae are unicellular organisms such as Chlamydomonas, which resemble the gametes and zoospores of more complex chlorophytes. Some chlorophytes have even adapted to snowy habitats. Chlamydomonas nivalis can form dense algal blooms on high-altitude glaciers and snowfields, where its reddish pigments produce an effect called “watermelon snow”.

Ulva lactuca

• CC image via http://en.wikipedia.org/wiki/File:Ulva_lactuca.jpeg

• This edible seaweed has a multicellular thallus differentiated into leaflike blades. Its rootlike holdfast anchors the alga against turbulent waves and tides. The formation of true multicellular bodies by cell division and differentiation demonstrates how larger size and greater complexity evolved in choroplasts.

Caulerpa prolifera

• CC image via http://www.reefcorner.com/images/FeatherCaulerpa.jpg

• Caulerpa, is an intertidal chlorophyte in the green algae subgroup of Archaeplastida. The branched filaments lack cross walls, and thus are multinucleate. In effect, the thallus is one huge supercells. This repeated division of nuclei with no cytoplasmic division contributed to the evolution of larger and more complex choropytes.

Entamoeba Histolytica

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• Humans are host to at leas six species of Entamoeba, but only one, E. Histolytica, is known to be pathogenic. E. Histolytica causes amebic dysentery and is spread via contaminated drinking water, food, or eating utensils. Responsible for up to 100,000 deaths worldwide every year, the disease is the third-leading cause of death due to eukaryotic parasites, after malaria and schistosomiasis.

Dictyostelium discoideum

• CC image via http://en.wikipedia.org/wiki/File:Dictyostelium_Fruiting_Bodies.JPG

• Dictyostelium, a cellular slime mold, is an individual organism. The feeding stage of these organisms consists of solitary cells that function individually, but when food is depleted, the cells form an aggregate that functions as a unit. Cellular slime molds differ from plasmodial slime molds in being haploid organisms.

Fuligo septica

• CC image via http://en.wikipedia.org/wiki/File:Dog_vomit_slime_mold.jpg

• Fuligo septica, better known as the dog vomit slime mold, is part of the subgroup Amoebozoans. Plasmodial slime molds form a single mass of cytoplasm, called a plasmodium, that is undivided and that contains many diploid nuclei. This supercell is the product of mitotic nuclear divisions that are not followed by cytokinesis.