Zoology Ch 8 Animal Like Pro Tists

Animal-Like Protists: The

ProtozoaChapter 10

Protists• Zoologists recognize between 7-45 Phlya of Protists

• This group is Polyphyletic- traced to separate ancestors

• Some are plant-like• Some are animal-like

Figure 11.01

Protozoa:• Are complete organisms in which all life activities are carried on within a single plasma membrane.

• Unicellular• Eukaryotic

Maintaining Homeostasis

Maintaining Homeostasis

• Cytoplasm has 2 regions–Ectoplasm- just beneath pellicle, clear and firm

–Endoplasm- granular and fluid, inner cytoplasm

See figure 8.3

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Fig. 8.3

W. D. Russell-Hunter, A Life of Invertebrates, © 1979.

Protozoan Protist

Maintaining Homeostasis

• Freshwater protozoa must regulate water because of osmosis.

• Contractile vacuoles or water expulsion vacuoles- remove excess water

Maintaining Homeostasis

• Cytopharynx- ingest food in a specialized region(analogous mouth)

• Food vacuoles-digest and transport food

• Cytopyge- specialized region to release waste

Maintaining Homeostasis

• Large surface area to volume ratio

–Gas exchange of oxygen and carbon dioxide

–Excretion of nitrogenous by products

–All happens by diffusion

Reproduction• Both asexual and sexual reproduction can occur.

• But most do mainly asexual.

Types of Asexual Reproduction

• Binary fission•Mitosis produces 2 new nuclei•Cytoplasm divides (cytokinesis)

»Longitudinal or transverse.•2 new organisms that are identical.

Binary Fissionhttp://protist.i.hosei.ac.jp/PDB/PCD1502/animation/DividingAmoeba.html

One is the loneliest number. . .

Unless you can do

OK now you do it!

Binary fission

Types of Asexual Reproduction• Budding

•New individuals arise from outgrowths of existing ones.

•Offspring may either detach from the parent or remain joined forming colonies.

Types of Asexual Reproduction

• Multiple fission or schizogony•Large number of daughter cells from the division of a single protozoan

•Many multiple mitotic nuclear divisions

•Cytoplasm divides, multiple new cells

Multiple fission or schizogony

Symbiotic Lifestyle

• Many protozoa have symbiotic lifestyles.

• Symbiosis- intimate association between two organisms.

• Three types: parasitism, commensalism, mutualism

Symbiotic Lifestyle

• Parasitism- one organism lives in or on a second organism, called a host

Parasitism• Definitive host-sexual stages of the parasite

• Intermediate host-when sexual stages produce offspring, enter this host, reproduce asexually.

• Many protozoa are parasites

Symbiotic Lifestyle

• Commensalism- one organism benefits and second is neither benefited or harmed.

Symbiotic Lifestyle

• Mutualism-both organisms benefit.

Taxonomy• Protozoologists: zoologists who specialize in the study of protozoa

• Found out that Protista Kingdom to diverse to put into one Kingdom

• Many protist phylum have been elevated to kingdom status

4 Major Categories of

Protozoa• Flagellated Protozoa• Amoeboid Protozoa• The Coccidea• The Ciliates

Flagellated Protozoa• Possess one to many flagella used for locomotion.

• Produce whip-like or helical movements

• Push or pulls protozoan through aquatic medium

Flagellated Protozoa

• Both Flagella and Cilia ( both used for locomotion) share a common ultrastructure.

Flagellated Protozoa

• 9 doublets (pairs) of microtubules arranged in a ring

• In center of the ring 2 single microtubules.

• Anchored in the cell by a basal body (centriole)

Flagellated Protozoa

The 9 + 2 arrangement

Flagellated Protozoa

• Many phyla represented• All possess pellicle for shape

• Two major groups:

Phytoflagellated

Zooflagellated

Phytoflagellate

• Possess chlorophyll• Produce large portion of food in marine food webs

• Oxygen in aquatic habitats come from them

Phytoflagellate

Dinoflagellates (dino= whirling)Marine and freshwater phytoplanktonTransverse groove 1-2 flagella-makes them whirl or spinOne trailing flagella pushes organism forward

Phytoflagellate

Dinoflagellates (dino= whirling)

PhytoflagellateDinoflagellates (dino= whirling)

Blooms (explosive population growth) can cause “red tide”Blooms appear brownish red or pinkish orange b/c of presence of carotenoidsToxins produced by some can cause massive kills of invertebrates and fish

This massive “red tide” of the dinoflagellate Noctiluca stretched for more than 20 miles along the southern California coast. Non-toxic blooms such as these can cause extensive mortalities of plants and animals in shallow waters when the bloom biomass decays, stripping oxygen from the water. (P. Franks)

Phytoflagellate

Dinoflagellates

Some can be bioluminescentOrganisms feed on them, the light attracts fishes that eat those predators

On the island of Vieques off the coast of Puerto Rico, Mosquito

Bay’s dinoflagellates

Making angel’s wings by sweeping her arms, Mosquito Bay tour guide Sharon Grasso lights up the surfaceof the water

Kayaking on the bay on the bay

Phytoflagellate

EuglenaFreshwater protozoa

ChloroplastIf cultured in dark feed by absorption and lose green color

PhytoflagellateEuglena

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Fig. 8.7

Structure of Euglena

Subphylum Mastigophora

(cl. Phytomastigophora)

Zooflagellate• Lack chloroplast• Heterotrophic• Some are parasites of humans

Zooflagellate

Trypanosomes bruceiParasite that causes African sleeping sickness

ZooflagellateTrypanosomes brucei

Tsetse flies are the intermediate hosts

Trypanosomes brucei life cycleTsetse fly bites an infected human

Trypanosomes multiply asexually in gut of flyTrypanosomes migrate to salivary glands transform thru number of body formsTsetse fly bites human, parasite in blood and multiplies asexually and transform thru number of body forms again

Trypanosomes brucei life cycle

• In human, parasite can live in blood, lymph, spleen, central nervous system, and cerebrospinal fluid

• If the parasite travels to the central nervous system this causes mental dullness, lack of coordination, “sleepiness”.

Trypanosomes brucei life cycle

ZooflagellateTrypanosomes cruziParasite that causes Chagas disease

Carlos Chagas

ZooflagellateTrypanosomes cruziKissing bugs are the intermediate hosts

ZooflagellateTrypanosomes cruziare shed in the feces of the bug and are inoculated into the human host by scratching infected feces into skin abrasions usually caused by the bug in the process of feeding (blood-sucking).

The feeding Kissing Bug

Amoeboid Protozoa• Move by Pseudopodia- temporary cell extensions usually of the ectoplasm and endoplasm for feeding and moving

PseudopodiaTypes:1. Lobopodia: broad extensions used for

locomotion and engulfing food2. Filopodia: provide constant two-way

streaming that delivers food in a conveyor belt fashion

3. Reticulopodia: similar to filopodia, except they extend out and form net-like series of extensions

4. Axopodia: thin, filamentous and supported by a central axis of microtubules

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Fig. 8.10

Variations in Pseudopodia

Pseudopodia

Amoeboid ProtozoaMost familiar amoebozoans are Rhizopodans

Naked- no test (shell)Live in shallow

freshwater

The AMOEBA

Amoeboid ProtozoaFeed on other protists

and bacteria by Phagocytosis

Phagocytosis

Amoeboid Protozoa

Binary fission occurs

Amoeboid Protozoa

Entamoeba histolyticaCauses dysentery in humansInflammation of lower intestinal tractDebilitating diarrheaNeeds no intermediate host

The CoccideaPhylum Apicomplexa All parasitesNo cilia or flagella (except in reproductive stages)Apical Complex for penetrating host cells

The Coccidea

Phylum ApicomplexaLife cycles typically asexual (schizogony, sporogony) some sexual (gametogony) phases

APICOMPLEXA

The CoccideaPlasmodium

Causes malaria (4 different species)Has devastated mores armies than has actual combatOver 100 million humans annually contract the disease, 2 million die each year

Plasmodium Life cycle

Involves vertebrate (us) and mosquito host

Life cycle of malaria

Plasmodium has two hosts: mosquitoes and humans.

Sexual reproduction takes place in the mosquito and the parasite is transmitted to humans when the mosquito takes a blood meal

Life cycle of malaria: humans

• The mosquito injects Plasmodium into a human in the form of sporozoites.

• The sporozoites first invade liver cells and asexually reproduce to produce huge numbers of merozoites which spread to red blood cells where more merozoites are produced through more asexual reproduction.

•

Life cycle of malaria: humans

• Some parasites transform into sexually reproducing gametocytes and these if ingested by a mosquito continue the cycle.

Life cycle of malaria: mosquitoes

• Gametocytes ingested by a mosquito combine in the mosquito’s stomach to produce zygotes.

• These zygotes develop into motile elongated ookinites.

Life cycle of malaria: mosquitoes

• The ookinites invade the mosquito’s midgut wall where they ultimately produce sporozoites, which make their way to the salivary glands where they can be injected into a new human host.

Malaria – Life cycle

Malaria caused by Plasmodium

The Coccidea

CryptosporidiumCauses chronic diarrhea and the only known protozoan to resist chlorinationTransmitted through water, food, animal-to-human and human-to-human contact

The Coccidea

Cryptosporidium

The CoccideaToxoplasma

Cat only host with sexual stage – sheds from intestinal tractMode of transmission : fecal oral from cat or oral (raw meat)

Toxoplasma

Once infection occurs most develop an effective immunityIf a woman is infected near time of pregnancy or during, congenital toxoplasmosis may develop in the fetusMajor cause of stillbirths and spontaneous abortions

The Ciliates• Complex protozoan • Fresh and marine

environments• All have 9 +2 cilia for

locomotion and generation of feeding currents

Locomotion: cilia Cilia are generally similar to flagella

but are much shorter, more numerous and widely distributed over the surface of the organism

Trichocysts: used for protection, rodlike or oval structures that can be discharged and stuck to predators

Trichocysts

Phylum Ciliophora:

Other Characteristics:1. Relatively rigid pellicle and

more or less fixed shape2. Distinct cytostome (mouth)

structure3. Dimorphic nuclei, typically

larger macronuclei and one more smaller micronuclei

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Fig. 8.17b

Ciliate (Paramecium)

Ciliophora

Nutrition:

• some ciliates possess an oral groove

• cilia sweep food particles down this groove toward the cytopharynx where a food vacuole forms

• some ciliates even possess a cytopyge which is used to remove waste from the organism

Genetic Control and Reproduction

One Macronucleus- regulates daily metabolic activites

One or more Micronuclei- genetic reserve of the cell

Genetic Control and Reproduction

Can reproduce asexually by transverse binary fission or budding

Or some can reproduce sexually by conjugation

Conjugation:1. Random contact brings individuals of

opposite mating types together (called conjugants)

2. Meiosis results in four haploid pronuclei3. Three pronuclei and the macronucleus

degenerate. Mitosis and mutual exchange of pronuclei is followed by fusion of the pronuclei.

4. Conjugants separate. Nuclear divisions that restore nuclear characteristics of species follow. Cytoplasmic divisions may accompany these events

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Fig. 8.21

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Conjugation in Paramecium

Symbiotic Ciliates

Some are mutualistic by inhabiting the rumen of many hoofed animals

Balantidium coli is a parasitic ciliate that lives in the large intestine of humans, pigs, and other mammals.

EOC Figure

The End