Kingdom Chromista
The Alveolata
Protozoan Biodiversity
A guide to the major groups
Species seen in lab are marked with a
Alveolata
Alveolata
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All alveolates have tiny sacs (alveoli) beneath the
plasma membrane
All single-celled
Have tubular inner membranes (cristae) in their
mitochondria (Tubies).
Three major taxa with very different adaptive
strategies
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Dinozoa
 Dinoflagellates – some photosynthetic, others not
 Important in nearshore oceans
Apicomplexa
 (Mostly) medically important parasites; non-motile
Ciliophora
 Ciliates – conjugation
Dinoflagellates
Phylum Dinozoa = Dinoflagellata
Dinoflagellates
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Often classed with algae
Cell complexity
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How are their cells organized?
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Mesokaryotes – permanently condensed chromosomes
Mitotic spindle located outside of the nucleus (which
remains intact during mitosis)
What pigments do they possess?
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Single cells or chains of cells.
Chlorophyll a, Chlorophyll c and Peridinin.
What storage product is made?
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Starch and oils.
Dinoflagellates
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Cell wall features?
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Most dinoflagellates are encased in plates of
armor.
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Some are “naked” and lack these plates
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Thick cellulose plates encased in vesicles beneath the
cell membrane
Gymnodinium
2 flagella present.
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One trails behind
One lies in groove around center of cell
Cell spins slowly like a top as it swims
Ceratium
Gonyaulax: an armoured
dinoflagellate. Cell wall is
subdivided into multiple polygonal
vesicles filled with relatively thick
cellulose plates
A “naked” dinoflagellate. Cell wall does not have
thickened cellulose armour plates.
Armored dinoflagellate: Know: cingulum, sulcus, epitheca,
hypotheca, flagella
Dinoflagellates
Dinoflagellates
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Some have elaborate eyespots called ocelli, which
have a pigmented portion and a lens-like refractive
portion.
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Some have trichocysts, which are ejectile organelles
similar to the nematocysts in Cnidarians.
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What other group of protists has these?
Ceratium
Ceratium
Note: nuclei with permanently
condensed chromosomes
Dinoflagellates
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Mature dinoflagellates are haploid (1n)
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meiosis
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Dikaryotic nuclei – 2 haploid nuclei
Permanently condensed chromosomes
Reproduction
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Mostly asexual
Reproduce by fission
A few can reproduce sexually
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Gametes formed by mitosis (not meiosis) because the cells
are already haploid.
Gametes (1n) are motile
Zygotes (2n) formed by fusion of gametes also motile
Dinoflagellates
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Ecology
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90% are marine
10% freshwater
About 50% are photosynthetic; the rest are heterotrophs
(parasites)
Photosynthetic dinoflagellates are second only to
diatoms as primary producers in coastal waters.
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May be free-living or symbiotic
 Zooxanthellae - symbionts of cnidarians and others
 Vital to the growth and survival of coral reefs
Zooxanthellae
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Dinoflagellate endosymbionts of animals and
protozoa
Coral reef builders
Zooxanthellae
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Symbiotic dinoflagellates found in many marine
invertebrates
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Genus Symbiodinium
Sponges, corals, jellyfish, Tridacnid clams and flatworms
Also found within protists, such as ciliates, foraminiferans,
and colonial radiolarians.
Zooxanthellae
Zooxanthellae
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Endosymbionts of animals and protozoa
In coral polyps zooxanthellae are found in the
second layer of cells below the epidermis; one algal
cell per animal cell.
Important components of reef building corals*
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Provide them with nutrients
Remove waste
Contribute to the production of calcium carbonate
skeletons
* More about this when we study Cnidarians
Zooxanthellae
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Mutualism
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Host organism ingests the dinoflagellate and incorporate it
into its own tissues without harming it.
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Dinoflagellate divides repeatedly, and begins to
manufacture carbohydrates which are provided to the
host.
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Many corals get all their food from the zooxanthellae;
build reefs much faster with the dinoflagellates present in
their tissues.
Zooxanthellae
Zooxanthellae
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Recall observations on zooxanthellae in tissues of
Aiptasia anemones from S219 aquarium
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Cassiopeia jellyfish (aquarium) also have
zooxanthellae and typically rest upside down in
shallow mangrove beds.
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This provides maximum sun exposure for symbionts
Jellyfish also feeds on passing zooplankton
Blue structures are vesicular appendages that hold
zooxanthellae
Aiptasia anemone with zooxanthellae
The upper layer of the Acropora sp. is the
epidermis. The lower layer is the gastrodermis.
Within the cells are round to oval golden
spheres. These are the zooxanthellae.
Cassiopeia, the Upside-Down Jelly or Mangrove Jelly (Figure 7),
generally lies on upside-down on the substrate where it tends its
internal garden of zooxanthellae, which give it a greenish
color. While there, the bell margins pulsate creating a current
across the oral surface where plankton and other particles are
subdued by nematocysts and caught in a gelatinous coating. The
captured particles are carried to the mouth or to other secondary
mouths that occur on the oral arms. These are animals of warm,
shallow water of the West Indies, the Pacific, and the Indian Oceans.
Coral Bleaching = loss of zooxanthellae
Causes – discussed with Cnidarians
Bioluminescent
Dinoflagellates
Bioluminescence
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Some dinoflagellates are capable of producing
light - bioluminescence
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Molecules made by the organism produce light in
a chemical reaction.
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Luciferin and luciferase
 Same reaction that occurs in fireflies
Health Issues
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Many dinoflagellates produce neurotoxins
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Poisons that injure the nerves of marine life that feed on
the dinoflagellates
May cause massive kills of fish and shellfish, as well as
other forms of marine life.
If animals containing these toxins are eaten by humans,
the result may be illness or even death.
 Neurotoxins affect muscle function, preventing
normal transmission of electrochemical messages
from the nerves to the muscles by interfering with the
movement of sodium ions through the cellular
membranes
Health Issues
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These toxins in the water can blow inland in sea
spray and cause temporary health problems for
people who live near the coast.
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The toxin from Gonyaulax catenella is so toxic that
an aspirin sized tablet of the poison could kill 35
people; it is one of the strongest known poisons
Neurotoxins
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Saxitoxin - most common dinoflagellate toxin
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Brevitoxin
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100,000 times more potent than cocaine
Found in North American shellfish from Alaska to
Mexico, and from Newfoundland to Florida
Causes fish kills
May also cause poisoning in humans when it accumulates
in the tissues of shellfish
Red Tides
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Population explosions of dinoflagellates that can color the
water red.
Shellfish contain high levels of toxins during these times
Boat
Gonyaulax and views of red tides
A red tide results from a population
explosion of dinoflagellates (an algal
bloom). Cell densities are so high
that they turn the water a red color.
Bioluminescent
Red Tide
Noctiluca
Noctiluca - a bioluminescent
marine dinoflagellate; also
causes red tides. Can feed
heterotrophically by using its
longer posterior flagellum to
capture prey.
Neurotoxins
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Humans may be poisoned:
 By eating contaminated fish - Ciguatera
 Or by eating shellfish, such as clams or mussels paralytic shellfish poisoning or PSP.
Poisoning is serious but not usually fatal.
 Lethal concentrations lead to death from respiratory
failure and cardiac arrest within twelve hours of
consumption
 Old rule of thumb was that shellfish should only be
eaten during months with an "R" in them, and not
during May to August. Summer brings runoff of
nutrients and blooms of dinoflagellates. NOT VERY
RELIABLE!
Pfiesteria piscicida
Note the long flagella
Ulcers on fish caused (?)
by Pfiesteria
Pfiesteria and some of its relatives cause
death in fish and respiratory and neurological
complications in humans
Ciliates
Phylum Ciliophora
Functional groupings of ciliates
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Holotrich- uniform ciliation
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Heterotrich- possess membranes &/or cirri
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Peritrich- cilia only around the cytostome
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Colonial-living in colonies
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Suctorian- a clade of Ciliophora possessing
hollow feeding tentacles
An assortment of freshwater ciliates- biodiversity!
This figure shows 167 species- about 9500 species are known
Ciliophora (ciliates)
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A major clade within the Alveolates.
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Synapomorphies* of ciliates include:
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Ciliated pellicle and associated kinetodesmata
Dimorphic nuclei
Conjugation
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Primarily holotrophic - few parasitic.
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Many can form cyst stage (resting stage).
*Shared, derived characteristic – something NEW!
c
Ciliates
Paramecium
Paramecium bursaria
Stentor coeruleus
Vorticella
Stylonychia
Cirri
ciliary organelles used for food handling and locomotionform membranes or bundles
Ciliophora
Euplotes
a heterotrich ciliate
showing complex
cirri used for
feeding and
locomotion
Euplotes
Spirostomum
Didinium
http://www.uga.edu/protozoa/portal/images/movies/didinium.mov
Acineta
Sphaerophrya
Acineta
Acineta
Balantidiasis – Balantidium coli
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Most cases are asymptomatic.
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Diagnosis is based on detection of trophozoites in
stool specimens or in tissue collected during
endoscopy.
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Clinical manifestations, when present, include persistent
diarrhea, occasionally dysentery, abdominal pain, and
weight loss.
Symptoms can be severe in debilitated persons.
Repeated stool samples necessary to find trophozoites
Treatment: Tetracycline with metronidazole
and iodoquinol as alternatives
Trophozoites
Cyst
B. coli trophozoites
Ichthiopthirius multifilis (Ich)
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Common parasite of
freshwater and marine
fishes
Trophozoite burrows in
skin
Mature trophozoite
leaves fish and encysts.
Multiple mitoses produce
hundreds of “swarmers”
that reinfest fish.
Ich trophozoite in fin of
freshwater drum
M. C. Barnhart