Transcript Plant - like Protists

Algae – The Plant-like
Protists
Plant-like Protists
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Contain chlorophyll located in chloroplasts.
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Most make their own food through
photosynthesis.
Many have cell walls.
 Some have structures to hold them in
place.
 Some are one-celled, some are manycelled.
 Do not have roots, stems, or leaves.
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Importance of Algae
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Phytoplankton (photosynthesizing unicellular
algae) are the base of marine and fresh water
food chains.
Produce most of the oxygen on Earth through
photosynthesis.
Used as food and in industry.
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Examples:
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Carrageenan from cell walls of red algae is used in
toothpastes, pudding, cosmetics, and salad dressings.
Algin from the cell walls of brown algae is used in ice
cream, marshmallows, tires, and hand lotion.
Diatom shells are used in insulation, filters, toothpaste, and
road paint.
Six Main Groups of Plant-like Protists
Diatoms (phylum – Bacillariophyta)
 Dinoflagellates (phylum – Dinoflagellata)
 Euglenoids (phylum – Euglenophyta)
 Red algae (phylum – Rhodophyta)
 Green algae (phylum – Chlorophyta)
 Brown algae (phylum – Phaeophyta)
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Diatoms
Unicellular
 Photosynthetic
 Contain carotenoids along with
chlorophyll.
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Gives them a golden-brown color.
Found in both saltwater and freshwater.
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Make up a large component of the
phytoplankton population.
Diatoms
Store food as oil instead of starch which
lets them float near the surface of the
water.
 Secrete shells composed of silica, a glasslike substance.
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Each species has its own uniquely shaped shell
decorated with grooves and pores.
These shells drift to the bottom of the ocean
after the diatom dies, often forming thick
layers.
Diatoms
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Reproduce asexually by separating their shell in
half and then producing a new half to fit inside
each old half.
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This process produces offspring which are smaller than
the parent cells.
When the diatoms are ¼ of their original size,
they reproduce sexually, forming a full-size
diatom.
Dinoflagellates
Contain carotenoids and red
pigments, along with chlorophyll.
 Most are marine
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A major component of phytoplankton.
Most are photosynthetic though some are
also consumers.
 Move using two flagella that are at right
angles to each other.
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This causes the cell to spin slowly as the
flagella beat.
Dinoflagellates
Known as “fire algae” as many produce a
chemical that causes them to glow at
night.
 Many live symbiotically with jellyfishes,
mollusks, and corals.
 Several species produce toxins (such as
those that form red tides).
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Euglenoids
Have characteristics of both plants and
animals.
 Unicellular.
 Aquatic
 Do not have a cell wall but do have a
flexible pellicle made of protein that
surrounds the cell membrane.
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Euglenoids
Some use photosynthesis, some prey on
other organisms, and others use a
combination of both.
 Use one or more flagella to move toward
light or food.
 Have an eyespot, an adaptation sensitive
to light, that helps photosynthetic
euglenoids move towards the light.
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Red Algae
Commonly called seaweed.
 Most are multicellular.
 Contain chlorophyll and a red pigment.
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Can live up to 200 meters depth as the
pigments can absorb wavelengths of light
(green, violet, and blue) that can penetrate to
these depths.
Grow in tropical waters and along rocky
coasts in cold water.
 Use a structure called a holdfast to attach
to rocks.
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Green Algae
About 7,000 species have been classified
(most diverse algae).
 Contain large amounts of chlorophyll.
 Can be unicellular or multicellular.
 Most live in freshwater, but are also found
in oceans, moist soil, snow, on tree trunks
or in the fur of sloths.
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Green Algae
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May be unicellular, colonial, or
multicellular.
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May reproduce both asexually and
sexually through fragmentation.
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A colony is a group of cells that lives together
in close association.
During fragmentation, an individual breaks up
into pieces and each piece grows into a new
individual.
May be an ancestor of modern plants (due
to many similarities)
Brown Algae
Contain a brown pigment
along with chlorophyll.
 Live in cool saltwater.
 Multicellular and vary greatly in size.
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Kelp is the largest organism in the protist
kingdom.
Almost all brown algae live in salt water
along rocky coasts in cool areas of the
world.
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Many species have air bladders that keep their
bodies floating near the surface.