Protista & Fungi
EXERCISE 8
The protists and fungi are extremely diverse groups of organisms that we present together in order to introduce a variety
of life cycles in addition to biodiversity. For each specimen we examine, pay close attention to the nucleus condition,
haploid (n) vs. diploid (2n); where in its life cycle does gamete production, fertilization, meiosis, and spore production
occur; and any specialized stuctures assiciated with the processes.
Kingdom Protista
The diversity of protists is so great that they posses few characteristics in common. They are eukaryotic and represent
the Þrst group to evolve intracellular structures such as the true nucleus, golgi apparatus, endoplasmic reticulum, chloroplast, and mitochondrion. Moreover, ancient members of this group gave rise to the plants, animals, and fungi. Other
characteristics common to the protists are: almost all are found aquatic or semi-aquatic environments, most require aerobic conditions, most possess ßagella or cilia at some point in their life history, many are unicellular, and most are capable of producing cysts at some point in their life cycle that are resistant to drought of freezing.
Phyllogenetic relationships among many members of this Kingdom are uncertain and the subject of much debate. At
present, inclusion in the Kingdom Protista is a matter of convenience rather than representing distinct evolutionary
lines. However, protists can be grouped into three basic catagories based on morphological and life cycle traits: the protozoans, algae, and fungus-like protists. It is important to note, however, there is no clear distinction among these
groups. As an example, many ßagellated protozoans are closely related to the algae and even members of the same
genus have both colorless and chloroplast-containing members.
Protozoa
The name ÒprotozoaÓ means ÒÞrst animalsÓ, attributed because most orgamisms of this group engulf their food.
TABLE 52. Summary
of characteristics and examples of protozoan phyla.
Phylum
Characteristcs
Examples
Rhizopoda
possess pseudopods (false feet); lack
meisois and sexual reproduction; naked
or have shells; unicellular
Ameoba, Entamoeba histolytica (causes
amoebic dysentery) Entamoeba coli ( a
common gut commensal); Difßugia
Actinopoda
possess axopodia; usually have silica
skeletons and spines; unicellular
heliozoans (mostly freshwater) and
radiolarians (mostly marine)
Foraminifera
possess a calcareous shell; many with
commensal algae; unicellular
Apicomplexa (= Sporozoa)
mostly parasitic; complex life cycle;
unicellular
Plasmodium (causes malaria)
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TABLE 52. Summary
of characteristics and examples of protozoan phyla.
Phylum
Characteristcs
Examples
Zoomastigina
possess ßagella; unicellular or colonial
Trypanosoma (causes African Sleeping
Sickness, ChagasÕ disease), Trichomonas vaginalis; Giardia; ßagellates of
termite guts
Ciliophora
possess cilia for locomotion and feeding; unicellular or colonial
Stentor, Paramecium, Vorticella;
rumen ciliates
Algal Protists
These are the eukaryotic algae, which form the base of the food chain for most aquatic habitats.
TABLE 53. Character
Division (=
Phylum)
summary and examples of the major algal divisions.
Pigments
Cell Wall
Food
Store
Flagella
Body form
Other
Examples
Chrysophyta
(Golden
Algae)
chl a, chl c ,
b carotene
lorica of silica & cellulose
lipids &
laminarin
2; unequal
length
unicellular,
colonial
Fall dominant
Dinobryon,
Mallomonas
Bacillariophyta (Diatoms)
chl a, chl c ,
b carotene
silica
oils &
leucosin
none;
gametes Ð 2
unequal
unicellular,
Þlamentous, colonial
high
diversity
centrics &
pennates
Euglenophyta
chl a, chl c ,
b carotene
reinforced
pellicle
paramylon
2(1,3)
unicellular
stigma;
some colorless
Euglena,
Phacus
Pyrrophyta
(dinoßagellates)
chl a, chl c ,
b carotene
internal cellulose plates
starch
2 unequal,
in grooves
unicellular
red tides
Ceratium,
Gymnodiniun
Rhodophyta
(Red Algae)
chl a, biliproteins, a &
b carotene
ÔagarÕ
a glycan
none
unicellular,
Þlamentous, thallus
deep
tropical
marine
Batrachospermum, Rhodymenia.,
Polysiphonia
Phaeophyta
(Brown Algae)
chl a, chl c,
b carotene
cellulose,
other
polysaccharides
laminarin
none;
gametes Ð 2
unequal
thallus
cold
marine
Laminaria,
Fucus, Sargassum
Chlorophyta
(Green Algae)
chl a, chl b,
b carotene
cellulose
starch
0,2,4,many;
equal
unicellular,
Þlamentous, colonial
mostly
freshwater
Chlamydomonas, Volvox,
desmids, Spirogyra
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Kingdom Fungi
Fungus-like Protists
The slime molds and water molds resemble true fungi but they are not closely related to them. Slime molds are decomposers of rotten logs and leaf litter in forested ecosystems, while water molds decompose algae, leaves, and dead animals
in aquatic ecosystems. Some water molds are parasitic and grow on the skin of Þsh and amphibians or on plants.
TABLE 54. Summary
of characteristics and examples of fungus-like protists.
Phylum
Characteristics
Examples
Myxomycota (Plasmodial
Slime Molds)
ceonocytic, plasmodial feeding stage;
reproductive stage forms sporangia
Physarum, Stemonitus
Acrasiomycota (Cellular
Slime Molds)
solitary cells in feeding stage; reproductive aggregate forms sporangia
Dictyostelium
Oomycota (Water Molds)
hyphae have cellulose cell walls; diploid condition dominates
Phytophthora (causes potato blight),
ÔIckÕ infection on Þsh
Kingdom Fungi
The fungi are important decomposers of terrestrial environments as well as parasites of plants and animals. The basic
structure of multicellular fungi includes a thread-like net of hyphae (each thread), which collectively is called mycelium.
Hyphae of most fungi have cross walls, called septae, that divide the thread into cells. Other fungal hyphae are coenocytic, i.e., they lack cross walls.
TABLE 55. Summary
of characteristics and examples of true fungi.
Division
Characteritics
Examples
Zygomycota
asexual spores on sporangia; sexual spores:
zygospores
Rhizopus
Ascomycota
asexual spores: conidia; sexual spores Ð 8 ascospores
in ascus; fruiting body: ascocarp
Morchella, yeast
Basidiomycota
sexual spores: basidiospores on basidium; friuting
body: basidiocarp
Agaricus, toadstools, shelf
mushrooms
Deuteromycota
no sexual reproduction
Penicillium
Lichens
Lichens are an integrated symbiotic relationship between a fungus, usually an ascomycete, and a green or blue-green alga.
They can live in some of the most inhospitable habitats because each supplies what the other canÕt obtain on its own. The
fungus-part may supply moisture and nutrients, while the algae-part supplies the food source via photosynthesis.
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Exercises
1.
Examine the Mixed Protozoa culture under a compound microscope. Search for rhizopds such as Amoeba; ciliates
such as Paramecium, Vorticella, or Stentor; and ßagellates. Sketch and label your observations below:
2.
Examine the prepared slide of Actinosphaerium, an actinopod. Sketch the organism and label the axopodia.
3.
Examine the prepared slide of Trypanosoma lewisi, a parasitic ßagellate of rats. Sketch the ßagellate and a few blood
cells. How big are red blood cells and the trypanosome?
116BS/LBS 158H
Exercises
4.
View the demonstration of of termite gut ßagellates and rumen ciliates. Sketch two kinds of ßagellates and ciliate
from each sample.
5.
Examine the living culture of Mixed Diatoms and Desmids. Diatoms are bacillariophytes and can be recognized by
their golden chloroplasts and glass cell walls; whereas desmids are chlorophytes and have bright green chloroplasts.
Each desmid is composed of two semi-cells conjoined at the center. Can you differentiate the two types of algae?
Sketch and label one or two individuals of each type.
6.
Ask the TA to demonstrate a prepared slide of diatoms. Sketch several pennate and centric diatoms.
7.
View the specimen of Ceratium, a dinoßagellate, on demonstration. Sketch and label the cell wall, grooves, and ßagellae.
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8.
Observe cultures of Chlamydomonas and Volvox. Also obtain a prepared slide of Volvox sexual stages and note the
zygotes. Sketch your observations and label the chloroplast, mother and daughter colonies,
9.
Ask the TA to demonstrate various algae and protozoans in a pond water sample. (You may wish to observe the pond
water sample on your own too.) Be able to identfy the specimens to division and phylum levels. Sketch a few of the
organisms you Þnd.
10.
View the live specimens of Rhodophyta: Batrachospermum, cold-water stream, Þlamentous algae, and Rhodymenia, a
tropical marine thallus. Sketch your observations.
View the specimens of marine Phaeophyta on demonstration: Laminaria (a kelp), Fucus (rockweed), and Sargassum
(gulfweed). Identify holdfasts, ßoats, blades, and reproductive structures.
12. View cultures of Physarium, a myxomycete, under a stereo microscope. Note plasmic streaming of the plasmodium
and the fruiting structures.
11.
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Exercises
13.
Observe the moldy bread (Rhizopus) on display under the stereo microscope. Note the mycelium, sporangia, and sporangiophores. Place a small amount of the Rhizopus culture on a slide and sketch and label your observations. See also
prepared slides of Rhizopus conjugation and note the zygospore.
14.
Observe the Morchella, an ascomycete, on demonstration. Obtain a prepared slide of a Morchella cross-section and
sketch and label the mycelium, asci, and ascospores of the ascocarp.
15.
Observe various specimens of basidiomycetes on demonstration. Obtain a prepared slide of a Coprinus section and
sketch and label the mycelium, basidia and basidiospores of the basidiocarp.
16.
Observe the various lichen specimens on display. Obtain a prepared slide of a lichen section. Note the algal layer.
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120BS/LBS 158H