Protists
Kingdom Protista is the most diverse of all the kingdoms.
Are protists eukaryotes or prokaryotes?
Protists
Protists can be animal-like, plantlike, or funguslike.
• Protists are eukaryotes that are not animals, plants, or fungi.
Protists
• Animal-like protists consume other organisms.
– heterotrophs – single-celled
Protists
• Plantlike protists are photosynthetic.
– single-celled, colonial, or multicellular– no roots, stems, or leaves
Protists
• Funguslike protists decompose dead organisms.
– heterotrophs – can move, whereas fungi cannot
Protists
Protists are difficult to classify.
• Protista is one kingdom in the domain Eukarya.
Protists
• Protist classification will likely change.
Protists
II. Animal-like Protists Animal-like protists are single-celled heterotrophs that can move.
Protists
Animal-like protists move in various ways.
• Animal-like protists are often called protozoa.
macronucleus
food vacuole
oral groove
micronucleus
contractile vacuole
cilia
Protists
• Some protozoa move with flagella
Protists
• Some protists move with pseudopods.– change shape as they move – amoebas, for example
Protists
• Some protozoa move with cilia.
macronucleus
food vacuole
oral groove
micronucleus
contractile vacuole
cilia
– cilia help protists swim and capture food
Protists
Paramecia have contractile vacuoles to expel excess water. To avoid an obstacle, they back up, and move away in an avoidance reaction.
Protists
Some animal-like protists cause disease.
sporozoiteshuman liver
liver cells
developedparasites
red bloodcells
• Malaria is caused by Plasmodium and spread by mosquitoes.
Malaria Infection
Protists
Trypanosoma causes African sleeping sickness
Protists
Giardia is contracted from contaminated water
Protists
Protozoa can be beneficial
• One protozoan lives inside termites, digests wood.
• Both species benefit, so this is called mutualism.
Protists
III. Plantlike ProtistsAlgae are plantlike protists.Plantlike protists can be single-celled or multicellular.
colonycolony
daughter colonydaughter colony
Protists
Daughter colonies leaving the mother colony.
Protists
A. Euglenoids are a large group of plantlike protists.
pellicle
nucleus
chloroplast
eye spot
contractilevacuole
flagellum
– mostly photosynthetic, have one or two flagella
Protists
• Euglena moves toward the light, which is known as a positive phototropism.
• Has a red eyespot, which is light sensitive
Protists
B. Dinoflagellates are marine plantlike protists.
DinoflagellatesDinoflagellates
–may be bioluminescent – can cause red tide
Protists
Noctiluca scintillans
Protists
C. Diatoms are plantlike protists with shells.
– shells made of silica – produce large amounts of oxygen
Protists
More diatoms
Protists
• Multicellular algae are classified by their pigments.
– Green algae – Brown algae – Red algae
Protists
Red algae is used to make agar, food thickener, and medicine capsules.
Protists
Spirogyra : a type of green algae
Protists
IV. Fungus-like protists
• include slime molds and water molds • decomposers, like fungi • can move, like animals
Protists
• Slime molds
Protists
• Water molds are freshwater, funguslike protists.
– one type of water mold caused Great Potato Famine
of Ireland in the 1800’s – made of branching strands of cells – can be parasites of plants or fish