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