What Are Protists?
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Kingdom Protista
“odds and ends”
Eukaryotic organisms
Heterotroph, autotroph, or decomposer
• Several important characteristics:
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membrane-bound organelles
complex cilia and flagella
sexual reproduction with gametes
Multi – cellularity
Reproduction
• Asexually by binary fission, budding, and
fragmentation
• Sexually by fusion of gametes
Sexual Reproduction
• Occurs as a response to environmental stress
• Zygospore
– Adaptation that allows the zygote to survive freezing,
drying out, and sun exposure
• Multicellular protists can reproduce both sexually
and asexually via alternation of generations.
– consists of multi - cellular haploid and multi - cellular
diploid phases.
Classifying Protists
• How they they obtain nutrition
– Photosynthesis
– Breakdown organic material
– Capture and eat other protists
• Ecological role
Animal – Like Protists
• Protozoa “first animals”
• Ingest other organisms to obtain energy
• Unicellular, most can move, and most
reproduce asexually by binary fission
Amoeboid Protists
• Move by using extensions of their cells
called pseudopodia
– Pseudopodia are also used to surround and
engulf food particles
• Live in fresh water, in salt water, and in soil
• Free-living, but some are parasites
Ciliates
• Some of the most complex single - celled
organisms
• Most or all of the body is covered by short,
hair - like structures called cilia
• Move and hunt for food by beating their
cilia
Flagellates
• Protists that have whip-like structures called
flagella.
• Some flagellates also have cilia or form
pseudopodia.
• Can be free-living or parasitic
Sporozoans
• Animal-like protists that form spore – like
cells when they reproduce
• They lack flagella, cilia, and pseudopodia
and do not move.
• All sporozoans are parasitic and cause
diseases. (Malaria)
Plant – like Protists
• Include the organisms known as phytoplankton
and algae.
• Obtain energy through photosynthesis
• Vary in the types of pigments used in
photosynthesis and the kinds of molecules used
to store energy
• Diatoms, Dinoflagellates, algae
Diatoms
• Photosynthetic, unicellular protists with
unique double shells
• Their shells are made of silica or calcium
carbonate and have distinct patterns.
Dinoflagellates
• Unicellular protists that typically have two
flagella.
• Most are photosynthetic, but some are
heterotrophic
• Most have protective coats that contain silica.
Euglenoids
• Freshwater protists that have one or two
flagella.
• Many are photosynthetic, heterotrophic, or
both.
• Some have an eyespot that helps direct
them toward light.
Red Algae
• Most are multicellular and are usually found in
warm ocean waters.
• The pigments in red algae absorb blue light that
penetrates deep into water.
• Red algae grow at greater depths than other
algae.
• Some have calcium carbonate in their cell walls.
– These coralline algae play an important role in the
formation of coral reefs.
Brown Algae
• Multicellular protists that are found in cool ocean
environments.
• The largest brown algae are kelp that can reach
60 m (197 ft) in length.
• The body of a kelp has is made up of a holdfast,
a stipe, and blades
Green Algae
• Very diverse group of protist that form a
major part of marine plankton.
• Some inhabit damp soil and resemble plants.
• Some are symbiotic within the cells of other
organisms.
• Use chlorophyll for photosynthesis, starch to
store energy, and their cell walls contain
cellulose.
Fungus – like Protists
• Absorb nutrients from their environment
and reproduce by releasing spores.
• Slime Molds
• Water Molds and Downy Mildews
Protists and Humans
• Dysentery
– Contaminated water
– Giardia, amebiasis
• Toxoplasmosis
– Litter boxes and uncooked meat
– Flu – like symptoms
• Trichomoniasis
– Very common S.T.I
• Cryptosporidiosis
– Dysentery from uncooked meat and
contaminated water
• Chagas disease
– Kissing bug feces
– Few to no symptoms then can become chronic
with heart failure, swollen esophagus and large
intestine
Protists and the Environment
• Oxygen production and nutrient recycling
– Produce at least half of the Earth’s oxygen
• Food webs
– Primary producers
• Algal blooms
– Red tide and eutrophication
• Protists symbiosis
– Coral, lichen, ungulate digestion