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Protists
O’Connor
Protists
• organisms, comprising those eukaryotes
that cannot be classified in any of the
other kingdoms as fungi, animals, or
plants.
• they are unicellular
or
• they are multicellular without highly
specialized tissues.
How do they “eat”?
• Protists obtain nutrients & digest nutrients
in a complex acquirement & assimilation
system.
• Most protists also feed on bacteria.
• Protists acquire their food material through
internal digestion.
• They extend their cell wall & cell
membrane around the food material to
form a food vacuole via endocytosis.
Protozoa
• animal-like protists
• mostly single-celled, motile protists that
feed by phagocytosis, though there are
numerous exceptions.
• generally too small to be seen without
magnification.
• Some protists are heterotrophs
• Some protists are autotrophs
• Some get nutrients by decomposing
organic matter
Protozoa are grouped by method of
locomotion into
• Flagellates with long flagella e.g., Euglena Amoeboids
• with transient pseudopodia e.g., Amoeba Ciliates
• with multiple, short cilia e.g., aramecium Sporozoanon
• mobile parasites; some can form spores e.g., Toxoplasma
Algae, the plant-like protists
• include many single-celled organisms that are also considered
protozoa, such as Euglena
•
which many believe have acquired chloroplasts through
secondary endosymbiosis
•
Others are non-motile, and some (called seaweeds) are truly
multicellular
• Chlorophytes- green algae, are related to higher plants
– e.g., Ulva
• Rhodophytes- red algae
– e.g., Porphyra
• Heterokontophytes- brown algae, diatoms, etc.
– e.g., Macrocystis
Molds
• Slime molds, water molds & downy
mildews are fungus like protists that
decompose organic material to obtain
nutrients.
• Plasmodial and cellular slime molds
change in appearance and behavior
before producing reproductive structures
Slime Mold
Water Mold
Downy Mildew