Plantlike Protists: Algae
• Four phyla of unicellular algae
• Three phyla of multicellular algae
Plantlike -unicellular
• Cellular characteristics used to classify:
– Types of chlorophyll (a,b & c)
– Accessory pigments
– Absorb different wavelengths of light
– Reflect different wavelengths giving algae a
wide color range
Plantlike -unicellular
• Phylum Euglenophyta
– Freshwater lentic (still, ponds & lakes)
– Chloroplasts
– Paired flagella
– Swim & can live as heterotrophs!
– Reproduce by binary fission
Euglena
Euglena can become so
numerous it may turn
the water of a pond
bright green.
If you keep Euglenids in
the dark they start
feeding on organic
matter and may loose
their pigment. There
are many species
without chloroplasts.
Phylum Pyrophyta or
dinoflagellates
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~ 50% autotrophs, 50% heterotrophs
Most have two flagella
Cellulose “plates”
Many are luminescent
Genetic mystery
Phylum Pyrophyta or
dinoflagellates cont.
 Dinoflagellates (Dinophyta) are flagellated
protists.
 Many species have a beautiful textured
armor made of cellulose plates.
 One of their two flagella runs as a spiral
through a groove along the cell.
Pyrophyta or dinoflagellates:
It is not just protists that use
flagella for locomotion. Even
our own spermatozoa have
a flagellum.
Much of the bioluminescence in the sea comes from algae similar to this
tropical algae, Pyrocystis fusiformis.
Phylum Chrysophyta
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“Golden plants”
Have gold chloroplasts
Store food as oil not starch
Cell walls may contain pectin
Reproduce sexually and asexually
Phylum Chrysophyta
Phylum Bacillariophyta
the diatoms
 Diatoms
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One of the most abundant organisms
Cell wall of silicon (shells or tests)
Shaped like a pill box
Remains build up on ocean floor called:
Diatomaceous earth – has many uses
 Filters, abrasives (polishes), plastic products
 Also produces oil not starch
Phylum Bacillariophyta
the diatoms
Phylum Bacillariophyta
the diatoms
Important roles of unicellular algae
 Phytoplankton produce ~ 50% of Earth’s
O2 by photosynthesis
 Phytoplankton are the foundation of the
food web in most marine ecosystems
 Symbionts with coral animals
(dinoflagellates)
 Negative role: HAB- harmful algal blooms
3 (mostly) Multicellular Phyla
 Red algae - Phylum Rhodophyta
 Brown algae – Phylum Phaeophyta
 Green algae – Phylum Chlorophyta
RED ALGAE, Phylum Rhodophyta
 Red algae live at great depths up to 260M
Efficient light gathering pigments absorb
blue wavelength of light – reflect red
wavelength
 Range in oceans from polar areas to
tropics
 Most are multicellular with a complex life
cycle
Red Algae,P. Rhodophyta cont.
 Coralline algae helps stabilize coral reefs
Use CaCO3 in cell walls
 Important food source in Asia
Brown algae – Phylum Phaeophyta
 The largest size and most complex of all
algae
 Kelp “forests” individuals grow up to 60M
long
 Sargasso Sea – huge floating mats of
brown algae in the Atlantic near Bermuda
 Fucus or rockweed has holdfast, stipes (a
stem-like structure), bladder, & blades
Brown algae – Phylum Phaeophyta
Kelp
• Kelp forests are found
in cold waters
• Our Pacific Northwest
coastline has kelp
forests.
Green algae – Phylum Chlorophyta
 The most diverse group of algae ~ 7,000
species
 Many species unicellular
 Marine and freshwater habitats, even
moist areas on land
Green algae – cont.
 Likely ancestors to terrestrial plants
-Same type of chlorophyll a & b
-Cell walls with cellulose
-Store food in the form of starch
Green algae – cont.
 Unicellular
Reproduction of chlamydomonas
Green algae – cont.
 Colonial green algae
 Called volvox
Green algae – cont.
 Colonial green algae
 Filamentous algae
 Spirogyra: note
chloroplasts form
spirals
Green algae – multicellular
sea lettuce