The Protozoans

Kingdom Protozoa1

The Protozoans

Ciliates

Amoeboid Protozoans

Flagellated Protozoans

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Kingdom Protozoa

Defining Characteristics– All are unicellular eukaryotes– What is a prokaryote?– Many species are both heterotrophic and

autotrophic simultaneously or at different stages of the lifecycle

Eukaryote Cell

Prokaryote Cell

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Adaptability

Protozoans are ecologically important primary producers, consumers and as vital links in the food chain

Humans are greatly effected by parasitic protozoans either directly or indirectly – Effects range from irritating - fatal

Malaria (Plasmodium spp.) worldwide epidemic

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Reproduction

Asexual reproduction – Replication of chromosomes and the splitting of the

parent into two or more parts – Binary fission – Multiple fission – Budding

Protozoans are problematic in their associations as colonial forms

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Asexual Reproduction

Amoeba

CiliateFlagellate

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Classification

Kingdom Protozoa

Phylum Ciliophora (Ciliates)

The Sarcodinids (Amoeboid Protozoans)

Phylum Foraminifera

Phylum Radiozoa

The Flagellated Protozoans

Phytoflagellated protozoans

Zooflagellated protozoans

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Phylum Ciliophora

Defining characteristics– Body externally ciliated in at

least some lifecycle stages

Have the highest degree of subcellular specialization and are considered advanced protozoans

Paramecium feces

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Cilia

Cilia – Hair-like structures by

which the organism moves, collects food and senses their surroundings

Fastest of all the protozoans

Cilia structure

Ciliate Biology Oral groove

Cytostome

Cytoproct

Contractile vacuole

Paramecium

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Ciliate Lifestyles

65% of all ciliate species are free-living and mobile

Some ciliates form colonial aggregations and have sessile habits

Other ciliates have symbiotic relationships in invertebrates and vertebrates

Vorticella

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The Sarcodinids (Amoeboid Protozoans)

Contains 4 phyla: Foraminifera, Radiozoa, Amoebozoa, and Heliozoa

Most reproduce asexually through binary fission

Characterized by pseudopodia

Food is usually captured by phagocytosis

Body types range from free flowing to rigid with skeletal supports

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Phagocytosis

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Amebas and Humans

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Phylum Foraminifera

Defining characteristics– Individuals secrete

multi-chambered tests, generally made of calcium carbonate (CaCo3)

Foram. tests

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Foraminiferans

Extremely abundant, most are benthic and marine

Feed on diatoms and algae, very slow movers Organisms are extremely common and form

ooze– White cliffs of Dover are foraminiferan tests

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Phylum Radiozoa

Defining characteristics– Body is divided into distinct

zones separated by a perforated membrane or capsule

Have pseudopodia supported with thin microtubules that give a spiny rayed appearance

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Radiolarians

Have shells made of silicon dioxide that can be very intricate

Feed on diatoms and other phytoplankton Benthic individuals move by use of

pseudopodia – Can occur in large concentrations that form

ooze as well

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The Flagellated Protozoans

Characterized by the possession of a definite body shape and the possession of one or more flagella

Most species are free-living and mobile

Noctiluca

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Phytoflagellated Protozoans

Have chlorophyll and obtain energy directly from the sunlight

Some are strictly autotrophic or heterotrophic– Some are a combination of both

Both the Euglena and the dinoflagellates are examples of phytoflagellated protozoans

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Dinoflagellates

Know for bioluminescence and highly toxic red tides – Dense aggregations produce saxitoxin killing fish and

crustaceans Also contaminates shellfish causing diarrheic

shellfish poisoning Some benthic dinoflagellates produce a

neurotoxin that accumulates in tropical fish called Ciguatera

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Phytoflagellated Protozoans

Noctiluca

Euglena

Ceratium

Chlamydomonas

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Zooflagellated Protozoans

Free-living forms– Most individuals are sessile and have a single

flagellum that beats to obtain food and nutrients Parasitic forms

– 25% of zooflagellate spp. are parasitic in humans, invertebrates, and other vertebrates

– Usually have complex lifecycles with intermediate hosts

– Malaria is caused by the genus Plasmodium technically a member of the phylum Sporozoa

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Zooflagellated Protozoans

Choanoflagellates

Malaria (Plasmodium)