Protists
Chapter 19
I.
What is a Protist?
A. Kingdom Protista is a diverse kingdom,
including:
1. single or multi-celled organisms
2. heterotrophs or autotrophs
3. microscopic or large
4. all are eukaryotes
B. organisms can be animal like- Protozoa
1. all protozoa are unicellular
heterotrophs
2. usually reproduce asexually
3. grouped by the way they move
a. some have pseudopodiacytoplasm extensions that act
like false limbs
b. others use cilia or flagella to
move
4. Four main groups
a. amoebas- shapeless, have no cell
wall, use pseudopodia to move and feed,
forming them around their food, can live
in fresh or salt water, and usually
reproduce asexually
b. flagellates- have whip-like flagella for
movement
c. ciliates- use small hair like cilia that
cover their bodies to move, can live in
every type of aquatic environment
(ponds, streams, oceans), paramecium is
an example, usually divide through
asexual reproduction
d. sporozoans- produce spores,
reproductive cells that form w/out
fertilization and produce new organism, all
are parasites that live in hosts
C. Algae- plant like protists
1. use photosynthesis
2. can be single or multicellular
3. producer of oxygen & nutrients in
aquatic ecosystems (food source for
shellfish)
4. are not plants-lack roots, stems, &
leaves
5. Types divided in 6 phyla
a. Euglenoids- unicellular, aquatic
*have animal and plant characteristics
*most have chlorophyll &
photosynthesize
*can ingest food when light is absent
*have 1 or more flagella to move
toward light or food
b. diatoms- unicellular, photosynthetic
*shells made of silica
*make up large component of
phytoplankton (shellfish food!)
*store food they make as oil instead
starch, allows them to float
*reproduce asexually & sexually
of
c. dinoflagellates- have cell walls of thick
cellulose plates
* mostly marine, have 2 flagella causing
them to spin
*also make up a large component of
phytoplankton
d. Red algae- mostly multicellular marine
seaweeds
*body is called a thallus, lacks roots &
stems
*use “holdfasts” to attach to rocks
*red algae can live in deep water due
to their photosynthetic pigments, also
contain chlorophyll
e. Brown algae
*about 1500 species
* all live in salt water in cool areas
*contain chlorophyll and brown
carotenoid pigment
*many have air bladders that allow
them to float
*largest and most complex are kelp,
giant kelp can grow up to 60m long
f. Green algae
*most diverse group, more than 7000
species
*major pigment is chlorophyll
*most live in freshwater
*can be unicellular or multicellular
*can reproduce asexually or sexually
*have a complex life cycle
-examples: Volvox (lives in a colony),
Spirogyra (multicellular)
D. Funglike protists
1. slimemolds, downy mildews, and
water molds act like fungi
2. heterotrophic decomposers
3. Slime molds
a. beautifully colored, live in cool,
moist places, grow on rotting leaves or
decaying wood
4. water molds & downy mildews
a. live in water or moist areas
b. some feed on dead organisms,
others are plant parasites
c. can look fuzzy, like a fungus,
but produce flagellated
reproductive cells (fungi don’t)
d. downy mildew can cause
disease in many plants (Great
potato famine)