Kingdom Protista. KEY CONCEPTS Protists are a diverse group of eukaryotic organisms, most of which...

Kingdom ProtistaKingdom Protista

KEY CONCEPTSKEY CONCEPTS

• Protists are a diverse group of Protists are a diverse group of eukaryotic organisms, most of which eukaryotic organisms, most of which are microscopicare microscopic

ProtistaProtista

• Not a really valid “Kingdom” Not a really valid “Kingdom” • Few real evolutionary Few real evolutionary

relationshipsrelationships

• ContainsContains• AlgaeAlgae: “plant-like” protists: “plant-like” protists

• ProtozoaProtozoa: “animal-like” protists: “animal-like” protists

• Slime & Water moldsSlime & Water molds: fungal-: fungal-like protistslike protists

What Are Protists?What Are Protists?

• ““Dumping ground” Dumping ground” kingdomkingdom

• EukaryoticEukaryotic• Heterotrophic Heterotrophic

and/orand/or autotrophic autotrophic• Single Single oror

multicellularmulticellular• Ancestors to Ancestors to

animals, plants, animals, plants, fungifungi

Animal-like ProtistsAnimal-like Protists

• Called Protozoans• Unicellular• Require water

(live in water or moist soil)

• Most heterotrophic

• Some photosynthetic

• Most are free-living

• Some parasitic

All Life Functions in Just One All Life Functions in Just One CellCell

• Have food and Have food and waste waste VACUOLESVACUOLES for for storing and storing and digesting food & digesting food & wasteswastes

• Many are capable of Many are capable of MOVEMENTMOVEMENT

• RESPOND RESPOND to to environment – some environment – some have light sensitive have light sensitive eyespoteyespot

Amoeba

Paramecium

All Life Functions in Just One All Life Functions in Just One CellCell

• MaintainMaintain HOMEOSTASISHOMEOSTASIS

• Contractile Contractile VacuolesVacuoles pump out pump out excess waterexcess water

• Form Form Protective Protective Cysts Cysts when food or when food or water is scarce water is scarce (dormant stage (dormant stage with hard covering)with hard covering)

Contractile Contractile Vacuole Vacuole PumpingPumping

Plant-like ProtistsPlant-like Protists

Red Algae

Golden Algae

• Photosynthetic• No true roots, stems, leaves

Plant-like ProtistsPlant-like Protists

Green Algae

Red AlgaeBrown Algae

Golden Algae

• Photosynthetic• No true roots, stems, leaves

Fungi-like ProtistsFungi-like Protists

• Heterotrophic• Decomposers• No cell walls Slime Molds

Water Molds

ReproductionReproduction

• Reproduction Reproduction • Asexual: Asexual: fissionfission

• Sexual: produce Sexual: produce gametesgametes (specialized (specialized sex cells)sex cells)

• Advantage: new combinations of genesAdvantage: new combinations of genes from both parents (Red Queen Hypothesis)from both parents (Red Queen Hypothesis)

ReproductionReproduction

• All reproduce All reproduce ASEXUALLYASEXUALLY

• Binary Fission Binary Fission - - divides into 2 divides into 2 identical identical individuals individuals (clones)(clones)

• RapidRapid reproductive reproductive raterate

Some Reproduce SEXUALLYSome Reproduce SEXUALLY

ConjugationConjugation - - Opposite mating strains Opposite mating strains pair and exchange genetic material pair and exchange genetic material (DNA)(DNA)

Protist Protist CharacteristicsCharacteristics

General CharacteristicsGeneral Characteristics

• EukaryoticEukaryotic• Unicellular Unicellular • Some may live in coloniesSome may live in colonies• May be Autotrophic or May be Autotrophic or

Heterotrophic or BothHeterotrophic or Both• Some are motileSome are motile• Appeared about 1.5 BYAAppeared about 1.5 BYA

Classified into Three Main Classified into Three Main GroupsGroups

• Animal-likeAnimal-like… heterotrophs … heterotrophs capable of locomotioncapable of locomotion

• Plant-likePlant-like… photosynthetic … photosynthetic autotrophsautotrophs

• Fungus-likeFungus-like… decomposers … decomposers that reproduce by sporesthat reproduce by spores

• Some protists Some protists may exhibit may exhibit both animal-like & plant-like both animal-like & plant-like characteristicscharacteristics

Sizes of ProtistsSizes of Protists

• UnicellularUnicellular organisms organisms• microscopicmicroscopic

• ColoniesColonies• loosely connected groups of cells loosely connected groups of cells

• CoenocytesCoenocytes• multinucleate masses of cytoplasm multinucleate masses of cytoplasm

• MulticellularMulticellular organisms organisms• composed of many cellscomposed of many cells• can get very large – some brown algae can get very large – some brown algae

(the giant kelps) can be 100 feet in length(the giant kelps) can be 100 feet in length

LocomotionLocomotion

• Protozoa used to be classified according to Protozoa used to be classified according to how they move.how they move.• Ciliates use fine “hairs” called Ciliates use fine “hairs” called ciliacilia

• Flagellates use longer, whip-like hairs called Flagellates use longer, whip-like hairs called flagellaflagella

• Amoebas and their relatives use Amoebas and their relatives use pseudopodiapseudopodia• Pseudopodia are also used to capture foodPseudopodia are also used to capture food

• Sporozoans (apicomplexans) don’t have any Sporozoans (apicomplexans) don’t have any ability to move (ability to move (non-motilenon-motile))

ImportanceImportance

• Importance of ProtistsImportance of Protists• HeterotrophicHeterotrophic protists = protists = protozoaprotozoa

• Consume bacteriaConsume bacteria and other protists and other protists• Components of aquatic and soil Components of aquatic and soil food food

webswebs• help with help with recycling nutrientsrecycling nutrients

• Some cause Some cause diseasedisease• MalariaMalaria• DysenteryDysentery• Sleeping sicknessSleeping sickness• othersothers

InteractionsInteractions

• Protists are free-living or Protists are free-living or symbioticsymbiotic

• Symbiotic relationships range from Symbiotic relationships range from mutualismmutualism to to parasitismparasitism

Classification of Selected Classification of Selected Medically Important ProtozoaMedically Important Protozoa

• Four groupsFour groups• Mastigophora - flagellatesMastigophora - flagellates• Sarcodina - amoebaeSarcodina - amoebae• Ciliophora - ciliatesCiliophora - ciliates• Apicomplexa – aka SporozoansApicomplexa – aka Sporozoans

• Based on:Based on:• Method of motilityMethod of motility• Mode of reproductionMode of reproduction• Stages in the lifecycleStages in the lifecycle

Animal-like Animal-like ProtistsProtists

classified by classified by method of method of movementmovement

Phylum Rhizopoda Phylum Rhizopoda (formerly Sarcodina) : ex. (formerly Sarcodina) : ex.

AmoebaAmoeba

The The AmoebaAmoeba uses usespseudopodiapseudopodia for for

locomotion.locomotion.

The The AmoebaAmoeba in 3D – in 3D – notice the pseudopodsnotice the pseudopods

AmoebaAmoeba surround and engulf surround and engulf their food… the process is their food… the process is

called called phagocytosisphagocytosis..

An An AmoebaAmoeba eating a eating a ParameciumParamecium..

CiliophoraCiliophora

• all use cilia for movementall use cilia for movement• have many specialized have many specialized

structures, including mouths, structures, including mouths, anal pores, contractile vacuoles, anal pores, contractile vacuoles, and two nuclei (a large and two nuclei (a large macronucleus and small macronucleus and small micronuclei)micronuclei)

• Ex. – Ex. – ParameciumParamecium and and StentorStentor

Phylum Ciliophora: ex. Phylum Ciliophora: ex. ParameciumParamecium

3D view – taken by a 3D view – taken by a scanningscanning

electron microscopeelectron microscope

A closer look at the A closer look at the Cilia…. Cilia….

its means of locomotionits means of locomotion

another Ciliate: another Ciliate: StentorStentor

Phylum Phylum ZoomastigophoraZoomastigophora

• have flagellahave flagella• some species of some species of

zooflagellates zooflagellates have mutualistic have mutualistic relationshipsrelationships

• ex.- ex.- Trichonympha Trichonympha digests cellulose digests cellulose in the guts of in the guts of termitestermites

Others are parasites, like Others are parasites, like TrypanosomaTrypanosoma, which causes, which causesAfrican Sleeping Sickness African Sleeping Sickness

(coma).(coma).

TrypanosomaTrypanosoma

TrypanosomaTrypanosoma

Tsetse Fly: carries Trypanosoma to humans; in other words, it’s a Vector

White Blood Cell

Red Blood Cells

Trypanosoma

Phylum SporozoaPhylum Sporozoa• are parasitesare parasites• have no means of locomotionhave no means of locomotion• form spores that are form spores that are

dispersed by one or more dispersed by one or more hosts hosts

• ex. ex. PlasmodiumPlasmodium, which , which causes malariacauses malaria

Portions of the Life Cycle of Portions of the Life Cycle of Plasmodium vivaxPlasmodium vivax

It’s Vector:

Anopheles

Mosquito

Plasmodium vivax

Red Blood Cells

Pathogenic Flagellates: Pathogenic Flagellates: TrypanosomesTrypanosomes

• Giardia lambliaGiardia lamblia• Trichomonas vaginalisTrichomonas vaginalis• Genus Genus TrypanosomaTrypanosoma

• T. bruceiT. brucei causes sleeping sickness causes sleeping sickness• T. cruziT. cruzi causes Chagas disease causes Chagas disease

GiardiaGiardia

GiardiasisGiardiasis• Fecal-oral route of infectionFecal-oral route of infection

• recreational water, water, fomites, contaminated recreational water, water, fomites, contaminated uncooked fooduncooked food

• Symptoms normally begin 1 to 2 weeks (average 7 Symptoms normally begin 1 to 2 weeks (average 7 days) after becoming infected.days) after becoming infected.

• SymptomsSymptoms• Diarrhea Diarrhea • Gas or flatulence Gas or flatulence • Greasy stools that tend to float Greasy stools that tend to float • Stomach or abdominal cramps Stomach or abdominal cramps • Upset stomach or nausea Upset stomach or nausea

• May lead to weight loss and dehydrationMay lead to weight loss and dehydration• Symptoms of giardiasis may last 2 to 6 weeks. Symptoms of giardiasis may last 2 to 6 weeks.

Trichomonas vaginalisTrichomonas vaginalis

A flagellate - causes A flagellate - causes Trichomoniasis, a Trichomoniasis, a sexually transmitted sexually transmitted diseasedisease

TrichomoniasisTrichomoniasis

• STDSTD• Clinical Features:Clinical Features:

• Trichomonas vaginalisTrichomonas vaginalis infection in women is infection in women is frequently symptomatic. frequently symptomatic. 

• Vaginitis with a purulent discharge is the Vaginitis with a purulent discharge is the prominent symptom, and can be accompanied prominent symptom, and can be accompanied by vulvar and cervical lesions, abdominal pain, by vulvar and cervical lesions, abdominal pain, dysuria and dyspareunia.  dysuria and dyspareunia. 

• The incubation period is 5 to 28 days.  The incubation period is 5 to 28 days.  • In men, the infection is frequently In men, the infection is frequently

asymptomatic; occasionally, urethritis, asymptomatic; occasionally, urethritis, epididymitis, and prostatitis can occur. epididymitis, and prostatitis can occur.

Tsetse fly

Trypanosomes Trypanosomes (flagellates) in blood (flagellates) in blood

smearsmear

Kissing bugKissing bug

Tsetse FlyTsetse Fly

25 µm

Flagellum

Red bloodcells

Trypanosomewith undulatingmembrane

Figure 5.27

T. cruzi causes Chagas disease

East Africa West Africa

African Sleeping Sickness

African Sleeping SicknessAfrican Sleeping Sickness

• Bite reaction Bite reaction • Parasitemia Parasitemia

• attacks of fever which starts 2-3 weeks attacks of fever which starts 2-3 weeks after the biteafter the bite

• CNS Stage CNS Stage • changes in character and personality changes in character and personality

• Terminal stage is marked by wasting Terminal stage is marked by wasting and emaciation and emaciation

• Death results from coma, intercurrent Death results from coma, intercurrent infection or cardiac failure infection or cardiac failure

SarcodinaSarcodina (Amoebas) (Amoebas)

• PseudopodsPseudopods• Some have flagellated reproductive statesSome have flagellated reproductive states• Asexual reproduction by fissionAsexual reproduction by fission• Two groups have an external shellTwo groups have an external shell• Mostly uninucleateMostly uninucleate• Usually encystUsually encyst• Most free-livingMost free-living• ExamplesExamples

• EntamoebaEntamoeba• ForaminiferaForaminifera• RadiolariansRadiolarians

Figure 5.24

Infective Amoebas: Infective Amoebas: EntamoebaEntamoeba

• Amoebiasis caused by Amoebiasis caused by Entamoeba Entamoeba histolyticahistolytica

• Fourth most common protozoan Fourth most common protozoan infection in the worldinfection in the world

• Aka Aka amoebic dysenteryamoebic dysentery

Figure 5.28

Entamoeba histolytica

Entameoba histolytica

Causes amoebic dysentery (diarrhea) and can enter the liver, lungs, and brain

Naegleria fowleri

Foraminifera

Cyanophora paradoxaCyanophora paradoxa - has no - has no chloroplasts; contains an chloroplasts; contains an endosymbiotic cyanobacterium. endosymbiotic cyanobacterium.

Pelomyxa Pelomyxa has no has no mitochondria; this mitochondria; this amoeba depends on amoeba depends on aerobic bacterial aerobic bacterial symbionts to carry out symbionts to carry out respirationrespiration

More support for the theory: More support for the theory: Living organisms that contain Living organisms that contain endosymbiotic bacteria that carry endosymbiotic bacteria that carry out vital functions in the cell.out vital functions in the cell.

AmoebaeAmoebae

CiliophoraCiliophora (Ciliated) (Ciliated)

• Trophozoites mobile by ciliaTrophozoites mobile by cilia• Some have cilia in tufts for feeding and Some have cilia in tufts for feeding and

attachmentattachment• Most develop cystsMost develop cysts• Both macronuclei and micronucleiBoth macronuclei and micronuclei• Division by transverse fissionDivision by transverse fission• Most have definite mouth and feeding Most have definite mouth and feeding

organelleorganelle• Show relatively advanced behaviorShow relatively advanced behavior• Majority are free-living and harmlessMajority are free-living and harmless

CiliatesCiliates

Balantidium coliBalantidium coli

• Only known ciliate that is pathogenic in Only known ciliate that is pathogenic in humanshumans

• Affects humans, other primates, and pigs Affects humans, other primates, and pigs which are the reservoir which are the reservoir

• Lives in the large intestine and causes Lives in the large intestine and causes diarrhea diarrhea

• Trophozoites can also be detected in Trophozoites can also be detected in tissue. tissue.

• Collect a tissue specimen from the large Collect a tissue specimen from the large intestine, by sigmoidoscopyintestine, by sigmoidoscopy

TrophozoitesTrophozoites

CystCyst

• Most cases are asymptomatic.  Most cases are asymptomatic.  • Clinical manifestations, when Clinical manifestations, when

present, include persistent present, include persistent diarrhea, occasionally dysentery, diarrhea, occasionally dysentery, abdominal pain, and weight loss.  abdominal pain, and weight loss. 

• Symptoms can be severe in Symptoms can be severe in debilitated persons. debilitated persons.

• Diagnosis is based on Diagnosis is based on detection of trophozoites in detection of trophozoites in stool specimens or in tissue stool specimens or in tissue collected during endoscopy. collected during endoscopy. 

• Repeated stool samples Repeated stool samples • TreatmentTreatment

• Tetracycline with metronidazole Tetracycline with metronidazole and iodoquinol as alternativesand iodoquinol as alternatives

ApicomplexaApicomplexa (Sporozoa) (Sporozoa)

• Most not motile except male gametesMost not motile except male gametes• Complex life cyclesComplex life cycles• Produce Produce sporozoitessporozoites following sexual following sexual

reproductionreproduction• Important in transmission of infectionsImportant in transmission of infections• Most form oocystsMost form oocysts• Entire group is parasiticEntire group is parasitic• ExamplesExamples

• Plasmodium Plasmodium sppspp..• Toxoplasma gondiiToxoplasma gondii• Cryptosporidium parvumCryptosporidium parvum

Mosquito - transmits the Mosquito - transmits the malaria parasite malaria parasite Plasmodium Plasmodium vivaxvivax (a sporozoan)(a sporozoan)

Malaria parasite in Malaria parasite in red blood cellsred blood cells

Parasites breaking Parasites breaking out of red blood out of red blood cellscells

Malaria

ToxoplasmosisToxoplasmosis

ToxoplasmosisToxoplasmosis• Parasite causes eye and brain damage in a Parasite causes eye and brain damage in a

baby, if untreated. baby, if untreated.

• Acute infection in older children and adults Acute infection in older children and adults may be without symptoms, cause flu like may be without symptoms, cause flu like illness or enlarged lymph glands. illness or enlarged lymph glands.

• Latent parasite occurs very commonly in Latent parasite occurs very commonly in people infecting approximately a third to a people infecting approximately a third to a half of all humans. half of all humans. • Can cause active disease if a person becomes Can cause active disease if a person becomes

immune compromised immune compromised

Protozoan Identification and Protozoan Identification and CultivationCultivation

• Shape and size of cellShape and size of cell• Type, number, and distribution of Type, number, and distribution of

locomotor structureslocomotor structures• Presence of special organelles or Presence of special organelles or

cystscysts• Number of nucleiNumber of nuclei• Can be cultivated on artificial media Can be cultivated on artificial media

or in laboratory animalsor in laboratory animals

Toxoplasma gondiiToxoplasma gondii

• Clinical FeaturesClinical Features::• Generally an asymptomatic or mild self-limiting Generally an asymptomatic or mild self-limiting

infection.  infection.  • Immunodeficient patients Immunodeficient patients • brain lesionsbrain lesions• pneumonitispneumonitis

• Pregnant women/infantPregnant women/infant• miscarriage; still birthsmiscarriage; still births• cerebral palsey; seisurescerebral palsey; seisures• mental retardationmental retardation• eye infections; impaired eye infections; impaired

visionvision• enlarged liver and spleen enlarged liver and spleen

Cryptosporidium Cryptosporidium can be a can be a problem in municipal water problem in municipal water

supplies.supplies.

Cryptosporidium Cryptosporidium affects affects humans, dogs, and cattlehumans, dogs, and cattle

Cryptosporidium

Intracellular parasite

Causes diarrhea

Affects humans, cattle, sheep, dogs

No effective drug treatment for cryptosporidiosis

Antibiotics are contraindicated; supportive care only

Important Protozoan Important Protozoan PathogensPathogens

Phylum ForaminiferaPhylum Foraminifera

• have a protective shell or TEST, have a protective shell or TEST, usually made of calcium carbonateusually made of calcium carbonate

• layers of tests can deposit on the layers of tests can deposit on the ocean floorocean floor• these can form limestone and chalk, like these can form limestone and chalk, like

the White Cliffs of Doverthe White Cliffs of Dover• Some species of forams are good Some species of forams are good

indicators of oil deposits belowindicators of oil deposits below

Cliffs of Cliffs of DoverDover

Plant-like Plant-like ProtistsProtists

are classified byare classified by

CCOOLLOORR

Plant Like ProtistaPlant Like Protista

• Importance of ProtistsImportance of Protists• AutotrophicAutotrophic protists = protists = algaealgae

• Photosynthetic algae are the most important Photosynthetic algae are the most important primary producersprimary producers of the world’s freshwater of the world’s freshwater and marine ecosystemsand marine ecosystems• Many are microscopic Many are microscopic • Some are huge: kelpSome are huge: kelp

• Few cause diseaseFew cause disease• Toxic blooms of dinoflagellates causeToxic blooms of dinoflagellates cause• Red tidesRed tides• shellfish poisoningshellfish poisoning

Diatoms

Giant Kelp

Photosynthetic ProducersPhotosynthetic Producers

6 CO2 + 6H2O 6

C6H12O6

Photosynthesis

Respiration

Energy

Energy

Lake Trophic Lake Trophic LevelsLevels

ZooplanktoZooplanktonn

11o o

consumersconsumers

BluegillBluegill22oo

consumerconsumerss

Algae - Algae - producersproducers

BassBass33oo

consumerconsumerss

Osprey Osprey HumansHumans

44oo

consumerconsumerss

Phylum ChlorophytaPhylum Chlorophyta

• have both chlorophyll have both chlorophyll aa and and b b (so (so they are green)they are green)

• have cellulose cell wallshave cellulose cell walls• store carbohydrates as starchstore carbohydrates as starch• have many types of sexual have many types of sexual

reproductionreproduction• exhibit many types of organizationexhibit many types of organization

--Are thought to be the ancestors of --Are thought to be the ancestors of plants--plants--

Variations in Variations in Sexual Sexual

ReproductionReproduction• IsogamousIsogamous= both sperm and = both sperm and

egg are motile and equal in sizeegg are motile and equal in size• AnisogamousAnisogamous= both sperm and = both sperm and

egg are motile and differ in sizeegg are motile and differ in size• OogamousOogamous= large, nonmotile = large, nonmotile

egg and small, motile spermegg and small, motile sperm

Variations in Variations in Sexual Sexual

ReproductionReproduction

Phylum ChlorophytaPhylum Chlorophytaorganizationorganization

1. Unicellular1. Unicellular

2. Filamentous2. Filamentous

3. Colonial 3. Colonial

4. Bi-layer4. Bi-layer

Unicellular Green Algae Unicellular Green Algae ChlamydomonasChlamydomonas

ChlamydomonasChlamydomonas

Filamentous Green AlgaeFilamentous Green AlgaeSpirogyraSpirogyra

has spiral-shaped chloroplastshas spiral-shaped chloroplasts

another filamentous Green another filamentous Green Algae Algae ZygnemaZygnema

2 Star-shaped chloroplasts per 2 Star-shaped chloroplasts per cellscells

a colonial Green Algae … a colonial Green Algae … VolvoxVolvox

Mother colony with Daughter Mother colony with Daughter coloniescolonies

Mother Colony

Daughter Colony

a bi-layered Green a bi-layered Green AlgaeAlgae

UlvaUlva (sea lettuce) (sea lettuce)

Harvesting UlvaHarvesting Ulva

Phylum Phylum PhaeophytPhaeophyt

aa

• brown algaebrown algae• multicellularmulticellular• flagellated sperm flagellated sperm

cellscells• Ex.: Ex.: FucusFucus & Kelp & Kelp

Phylum Pheaophyta:Phylum Pheaophyta:Brown Algae… Laminaria… Brown Algae… Laminaria…

KelpKelp

Air Bladders:Used to take blades to the surface for

photosynthesis

Phylum Rhodophyta:Phylum Rhodophyta:Red AlgaeRed Algae

•are multicellular

•contain red accessory pigments called phycobilins

•gametes do not have flagella

• formerly known as Pyrrophyta or fire formerly known as Pyrrophyta or fire algaealgae

• have two flagellahave two flagella• some are bioluminescent, producing lightsome are bioluminescent, producing light• others produce nerve toxinsothers produce nerve toxins

• dinoflagellates are collected and dinoflagellates are collected and concentrated in filter-feeding animalsconcentrated in filter-feeding animals

• people who eat these animals become people who eat these animals become sicksick

Phylum Phylum DinoflagellataDinoflagellata

Phylum DinoflagellataPhylum Dinoflagellataex. ex. PeridiniumPeridinium

Red Tide- Red Tide- results from a results from a

bloom ofbloom of PeridiniumPeridinium

Phylum Bacillariophyta:Phylum Bacillariophyta: Diatoms… have tests (shells) that Diatoms… have tests (shells) that

contain silica (SiOcontain silica (SiO22), or glass), or glass

Diatom StrewDiatom Strew

Diatoms - a SEM Diatoms - a SEM picturepicture

Phylum Phylum EuglenophytaEuglenophyta

• have one to three flagella at their have one to three flagella at their leading (apical) endleading (apical) end

• have thin protein strips called have thin protein strips called pellicles wrapped over their pellicles wrapped over their membranesmembranes

• have an eyespot that permits have an eyespot that permits them to swim toward lightthem to swim toward light

• can become heterotrophic when can become heterotrophic when there is no lightthere is no light

Euglena Euglena (arrow indicates (arrow indicates anterior end)anterior end)

The Euglena uses a The Euglena uses a flagella as aflagella as a

means of locomotion.means of locomotion.

Phylum Phylum ChrysophytaChrysophyta

• Are golden yellowAre golden yellow• Have one or two apical Have one or two apical

flagellaflagella

MORE MORE Examples of Examples of

Autotrophic Protists Autotrophic Protists (Algae)(Algae)

Giant Kelp Forest

Desmids – a type of Desmids – a type of green algaegreen algae

Green and Green and golden algaegolden algae

SummerSummer

TabellariaTabellaria - a diatom Note the - a diatom Note the sheets of rectangular cellssheets of rectangular cells

AsterionellaAsterionella - a diatom - a diatom

DinobryonDinobryon

A chrysophyte algae – Early A chrysophyte algae – Early SpringSpring

Gonyaulax (another flagellate) and view of red tide

Fungal Like Fungal Like ProtistsProtists

HabitatsHabitats

• Most protists live inMost protists live in• oceanocean• freshwater pondsfreshwater ponds• lakeslakes• StreamsStreams• SoilSoil

• Parasitic protists live in body fluids Parasitic protists live in body fluids of hostsof hosts

Phylum Phylum Acrasiomycota: Acrasiomycota:

Cellular Slime MoldsCellular Slime Molds• have both fungus and protist characteristicshave both fungus and protist characteristics• spores germinate into amoebas that feed on spores germinate into amoebas that feed on

bacteriabacteria• When food is depleted, When food is depleted, cyclic AMPcyclic AMP is released, is released,

causing amoebas to aggregate into one unit causing amoebas to aggregate into one unit • the crowd of amoebas form a slug that the crowd of amoebas form a slug that

migratesmigrates• cells from the slug form a stalk with a capsule, cells from the slug form a stalk with a capsule,

which makes sporeswhich makes spores• spores are released, and the cycle repeatsspores are released, and the cycle repeats

Acrasiomycota Life CycleAcrasiomycota Life Cycle

Phylum AcrasiomycotaPhylum Acrasiomycotaaggregating aggregating

amoebasamoebascolony & fruiting

body

Phylum Myxomycota: Phylum Myxomycota: Plasmodial Slime MoldsPlasmodial Slime Molds

• grow as a single, spreading mass or grow as a single, spreading mass or plasmodiumplasmodium

• feed on decaying vegetationfeed on decaying vegetation• when the environment becomes unfavorable when the environment becomes unfavorable

(no food or water), they form stalks and (no food or water), they form stalks and spore-producing capsulesspore-producing capsules

• haploid spores germinate into amoeboid or haploid spores germinate into amoeboid or flagellated cellsflagellated cells

• these cells fuse to form a new diploid these cells fuse to form a new diploid plasmodiumplasmodium

Myxomycota Life CycleMyxomycota Life Cycle

MyxomycoMyxomycotata

Phylum Phylum OomycotaOomycota

• are parasitic and saprophyticare parasitic and saprophytic• form filaments, or form filaments, or hyphahyphae (like fungi)e (like fungi)• secrete enzymes into surroundings & secrete enzymes into surroundings &

absorb nutrients (like fungi) absorb nutrients (like fungi) • filaments lack filaments lack septasepta or or cross wallscross walls

resulting in many nuclei in a cell, they resulting in many nuclei in a cell, they are are coenocyticcoenocytic

• have cell walls made of cellulose, not have cell walls made of cellulose, not chitinchitin

Examples:Examples:• water moldswater molds• downy downy

mildewsmildews• white rustswhite rusts

OomycotOomycota a

Life Life CycleCycle

Leptomitus

Powdery Mildew

Phylum Phylum OomycotaOomycota

• potatoes are native to North potatoes are native to North America America

• they were introduced to Europe and they were introduced to Europe and became a staple of the dietbecame a staple of the diet

• during the summer of 1846 most of during the summer of 1846 most of the potato crop was destroyed by the potato crop was destroyed by Phytophthora Phytophthora (an oomycota)(an oomycota)

• nearly 1,000,000 Irish people died, nearly 1,000,000 Irish people died, and 1,500,000 emigrated to other and 1,500,000 emigrated to other countries, like the U.S.countries, like the U.S.

Pfiesteria piscicida.

Ulcers on fish caused by Pfiesteria

Note the long flagella

Evolutionary Evolutionary ConsiderationsConsiderations

• One group of flagellates, the One group of flagellates, the choanoflagellates, is thought choanoflagellates, is thought to have given rise to the to have given rise to the simplest animals, the simplest animals, the sponges.sponges.