! Protists live wherever there is water. So they
have contractile vacuoles.
Chapter 15 Protists!
! Kingdom Protista is probably the most diverse
group of living things.
! They can be plant-like, animal-like, or funguslike.
! Protists range in size from microscopic algae
to giant seaweeds.
! The one characteristic that they all have
in common is that they are all
eukaryotes.
What is a Protist?!
! Most are unicellular."
! Some are colonial. A few colonies have
evolved into multicellular organisms with
specialized structures.
The Biology of Protists - 1:12
! The most common way to group protists
is by how they obtain nutrition.
! Plant-like - autotrophs
! Animal-like - heterotrophs
! Animal-like are
called protozoans.
! They are grouped
according to their
means of
locomotion. (how
they move)
! Fungus-like - heterotrophs
Animal-like Protists – 1:48
Sarcodines - pseudopods!
Amoeba!
! An example would be an Amoeba
! Some sarcodines are surrounded by a shell.
(foraminiferens and radiolarians)
! An amoeba extends lobes of cytoplasm called
pseudopods to move and obtain food.
! When conditions become unfavorable an
amoeba can develop into a cyst.
! A cyst can withstand drought, heat, famine, or
ingestion by other organisms.
! When humans drink water contaminated with
parasitic amoeba they can get amoebic
dysentery.
Amoeba – 1:51
Zooflagellates - flagella!
! These protozoans use a whiplike flagella for
locomotion.
! They might use the flagella to swim in a certain
direction or just to move in a spinning fashion.
! Some use their flagella to create currents to
bring food.
! Some zooflagellates inhabit other organisms in a
symbiotic relationship. Like Trichonympha living
in the intestine of termites.
Ciliophorans - cilia!
! The most numerous and diverse group.
! Ciliates are protozoans that are covered with cilia.
! Cilia are short hairlike projections used for movement.
! A paramecium is an example.
! A paramecium has a macronucleus (everyday
functions) and a micronucleus(sexual reproduction).
! Most live in freshwater and can form cysts to survive
unfavorable conditions.
Paramecium – 1:19
Sporozoans!
Sporozoans - nonmotile!
! This group has no means of movement.
! Most are parasitic.
! Their life cycles are complex and involve both sexual
and asexual phases.
! In fact, their life cycle might include multiple hosts.
! An example would be Plasmodium. It is transmitted by
mosquito and causes Malaria in humans.
Sporozoans – 1:44
Unicellular Algae!
! Plant-like are
called algae.
Dinoflagellates
! They are
categorized as
unicellular or
multicellular.
Plant-like Protists – 3:47
! They are covered with
cellulose plates.
! They use a pair of flagella
for locomotion.
! Most are free-living marine
organisms.
! One species causes a
green glow in the ocean.
! One species causes “red
tides”.
Unicellular Algae!
Diatoms
! These are unicellular algae that look like
and have the variety of snowflakes.
! They have glass-like cell walls containing
silica.
! The walls have two parts that fit together
like pill boxes.
! Pores in the cell walls allow materials to
pass into and out of the diatom.
Killer Algae – Pfiesteria Piscicida :3:21
Unicellular Algae!
Diatoms!
Diatoms
! They have thousands of different
shapes and patterns.
! They are among the most abundant
organisms in the ocean.
! They have a high oil content.
! When they die their shells accumulate at
the bottom of the ocean as
diatomaceous earth.
Diatoms – 1:27
Unicellular Algae!
Euglenoids!
Euglenoids
! They resemble both algae and
protozoans.
! They lack rigid cell walls.
! They move about by using a flagella.
! They do have chloroplasts and carry out
photosynthesis.
Euglenoids – 1:37
Chlorophyta - green algae!
! Multicellular algae were once considered plants
because they contained chloroplasts.
! They are now considered protists because few
of them have true tissues.
! They also reproduce more like protists.
! We classify them according to the color of their
pigments.
! This group most closely resembles plants
because of the cell wall and the structure
of their chloroplasts.
! Some are unicellular like Chlamydomans,
which grows abundantly in ponds and
moist soils.
Chlorophyta - green algae!
! Some are multicellular
like Ulva, which are
made of flat, leaf-like
sheets.
! Ulva is found in the
ocean.
! Some are colonies like
Volvox, which might
include a thousand
cells.
Colonial Protists – 1:11
Chlorophyta - green algae!
Chlorophyta - green algae!
! Some
multicellular algae
like Spirogyra,
grow as filaments
with cells linked
end to end.
! Commonly found
in ponds.
Chlorophyta!
! Most green algae live in fresh water or
in moist soil.
! Many green algae live in symbiotic
relationships with other organisms.
! For example, a lichen, which is a green
algae and a fungus.
Green Protists - :54
Rhodophyta - red algae!
! They grow in warm, saltwater
environments.
! Some live near the surface and some
live as deep as 260 meters.
! At this depth, few wavelengths of light
are available for photosynthesis.
Phaeophyta - brown algae!
! They are multicellular.
! They live in cool saltwater habitats.
! This group includes the largest organism
in the Protista Kingdom.
! Giant Kelp
Rhodophyta - red algae!
! Red algae contains an
accessory pigment
that enables them to
use the available light.
! Their pigments can
also appear green,
orange or almost
black.
Phaeophyta - brown algae!
! Giant kelp can grow to
100 meters and live in
deep water beyond the
intertidal zone.
! They have specialized
structures called air
bladders to keep the kelp
afloat near the surface to
absorb sunlight.
Fungus-like protists!
! Some multicellular algae have complex
life cycles that alternate between a spore
producing stage (called a sporophyte
generation) and a gamete producing
stage (called a gametophyte generation).
! This type of life cycle is called alternation
of generations.
! They are small and live in
damp or watery places.
! They break down dead
organic material.
! A protist that acts as a
decomposer is known as a
mold.
! Most taxonomists divide the
molds into three groups:
Fungus-like protists!
! Plasmodial slime molds.
! Cellular slime molds.
! Slime molds have a shiny, wet appearance and
a texture like gelatin.
Fungus-like Protists – 1:19
Fungus-like protists!
Plasmodial slime mold
! In its feeding stage it is called a
plasmodium.
! Water mold.
! It can weigh as much as 50 grams and
grow as large as the palm of your hand.
! Water molds are fungus-like and live mostly in
the water.
! It is a single cell with many nuclei.
(multinucleated)
Fungus-like
protists!
Plasmodial slime mold
! When conditions become unfavorable a
plasmodium either creeps to a different location
or enters a different stage of its life cycle.
! It forms a structure called a fruiting body.
! The fruiting body produces spores, which are
carried by wind or animals to different
locations.
Fungus-like protists!
Plasmodial slime mold
Fungus-like
protists!
Plasmodial slime mold
! They can remain dormant for years.
! When the conditions become favorable
the spores release gametes that fuse to
form a diploid zygote.
! This zygote develops into a new
plasmodium.
Fungus-like protists!
Cellular slime molds
! It also alternates between a spore
producing, fruiting body form and an
amoeba-like feeding form.
! The feeding stage consists of small,
single cells that move, engulf and ingest
food.
Fungus-like protists!
Cellular slime molds
Fungus-like protists!
Cellular slime molds
! When conditions become unfavorable, the cells
secrete a chemical attractant that causes
nearby cells to clump together to form a
pseudoplasmodium.
! It is still made of independent cells.
! The cells of a pseudoplasmodium are haploid, a
plasmodial cell is diploid.
! Its fruiting bodies then produce spores.
Fungus-like
protists!
Water molds
! They have the appearance of cotton or fluff.
! They are decomposers in freshwater
ecosystems.
! They might decompose plants or animals.
! They have cell walls made of cellulose.
! When they reproduce asexually they produce
spores with flagella.
Fungus-like protists!
Water molds
! Algae and protozoans are the most numerous
organisms in the ocean.
! These organisms are the beginning of the aquatic
food chains.
! Plankton is made up of
zooplankton and
phytoplankton.
! Zooplankton is the protozoans.
! Plankton are mostly microscopic organisms that
float near the surface of oceans and lakes.
! Even one of the largest animals on the planet
feeds on plankton.
! Phytoplankton is the algae.
! The phytoplankton carries out
more than 70% of Earth’s
photosynthesis.
! Many protozoans are predators of
bacteria, keeping their numbers in
check.
! Seaweed has three complex
carbohydrates used in food products.
! Farmers use seaweed as livestock
feed or fertilizer.
! Carrageenan - a thickner and flavor
enhancer added to many dairy
products, such as milkshakes and
chocolate milk.
! We use diatomaceous earth in
products such as insulation, filters,
detergent, abrasives and polishing
agents in toothpaste.
! Agar - is sometimes used to thicken
soups, puddings and cake frostings.
! Diatom shells are also used in road
paint to make it reflect car headlights.
! Algin - pie filling, ice cream, French
dressing, syrups, toppings and
purees.
! Some people eat seaweed for its
mineral components especially
iodine.
! In Japan, sheets of red algae called
nori, are used to wrap sushi.
! Protozoans also make great
bioindicators.
Diseases caused either directly or
indirectly by Protists.!
! Plasmodium - malaria
! People with malaria often
experience fever, chills, and
flu-like illness. Left untreated,
they may develop severe
complications and die.
! Each year 350-500 million
cases of malaria occur
worldwide, and over one
million people die, most of
them young children in subSaharan Africa.
Diseases caused either directly or
indirectly by Protists.!
Diseases caused either directly or
indirectly by Protists.!
! Trypansoma - African sleeping sickness
! The most common vector is the tsetse fly, which may
spread the parasite to humans and animals through bites"
! Symptoms include headache, weakness, and joint pain in
the initial stages; anaemia, cardiovascular problems, and
kidney disorders as the disease progresses; in its final
stages, the disease may lead to extreme exhaustion and
fatigue during the day, insomnia at night, coma, and
ultimately death"
! Giardia - is the most frequent cause of non-bacterial
diarrhea in North America.
! Normally illness lasts for 1 to 2 weeks.
! Ingestion of one or more cysts may cause disease.
! Signs posted in wilderness areas often warn
about Giardia in streams. Commonly found in wild
animals such as the beaver, this graceful,
flagellated organism may infect unwary hikers.
Diseases caused either directly or
indirectly by Protists.!
! Gonyaulax - is one of the dinoflagellates
responsible for red tides.!
! During red tides, many fishes, whales,
manatees, and shorebirds have died in
massive numbers because of the toxic
conditions produced by dinoflagellate
blooms.!
! Gonyaulax gives us the gift of
bioluminescence.!
Diseases caused either directly or
indirectly by Protists.!
! Phytophthora
infestans - causes
late blight in some
vegatables.
! In the mid 1800’s a
potato blight
devastated the
potato crop in
Ireland.
The Value of Kelp – 3:04
Oil From Algae – 5:27
Protozoa – 20:51