Protozoans
Good book:
Tom Fenchel, Ecology of Protozoans
IBIT/Standort Wechloy: zoo 601 y94a BH 5722
Outer space?
Eukaryotic kingdom: plants, animals, fungi, plus many microbial eukaryotes
Formerly summarized as protists
Together with prokaryotes: 5 major phylogentic groups of life
Amazing size range!
• 4 orders of magnitude
• cover 1/3 of entire scale
IMPORTANT:
size corresponds to individual cell size
Contrary: size in metazoans is given by
number of cells
Size limitation due to oxygen diffusion
Mesoplankton 20-200 µm)
Microplankton 20-200 µm)
Nanoplankton 20-2 µm)
Picoplankton 0.2-2 µm)
Flagellates
Occurence: water, humid niches
Solitary, groups
Characteristic flagellum
Generally heterotroph
assimilation via plastids, autotrophy
Reproduktion mostly asexual, via fission
Rhizopodes:
Characteristic peudopodia, elongated
structures
Organelles to take up food
Flat, amoeba
Pathogenicity:
Tooth plaque (Entamoeba
gingivalis)
Human gut Entamoeba coli,Entamoeba
histolytica
If imune system of host is weak, they turn into
pathogenic forms, e.g. prey on erythrocytes
Sporozoa:
Characteristic apical structures
Conoid: Penetration of host cell, live exclusively as
parasites (plasmodium vivax, Malaria; fever pulses when
sporozoa multiply in erythrocytes)
Reproduktion:
mostly haploid, gametogenesis, sporogenesis
Ciliates:
Most highly organized life form among protozoa. Characteristic cilia
Lokomotion via cilia beating
Nuclear duality, i.e. one large nucleus (macronucleus, metabolism), one small
nucleus (micronucleus, reproduction)
Suspension feeders, and and direct predation on other protozoa or bacteria (via
Cytostom)
Food storage in vacuoles, enzymatic digestion
Reproduktion:
Sexual and asexual
Nucleus
Food vacuole
Water expelling
vacuole
Foraminifera:
Fossil records 109 years ago
White cliffs of Dover
Colonial protozoa
Polykrikos schwartzi
Zoothamnium hiketes
dinoflagellate
Volvox: colonial flagellate
Intermediate between true multicellular organism and agglomeration of unicellular organism
• Each sphere consists of up to 1000 individual cells
• Within „mother“shere (ca. 500 µm) daughter colonies develop
For more information see:
http://www.hydro-kosmos.de/jahresz/herbst/hm2.htm#Wimperkugel
• Cells are connected by plasma threads
• Flagella point outwards, locomotion
• Egg & sperm cells develop
• Leave the mother sphere
Borderline between unicellular and multicellular mode of life
Movie:
Dictyostelium discoideum
See: www.vcell.de/genomstation/dictyostelium_discoideum.html
Reproduction:
Paramecium bursaria (with chlorella cells)
Symbionts
Parablepharisma pellitum
Hypothesis:
Anaerobic protozoan, produce H2,
bacteria are methanogens which
oxidise H2 with CO2
Alexandrium tamarense (dinoflagellate)
• Red tides
• Filter feeding mussles (mytilus, clams, oysters)
• Paralytic shellfish poisening (PSP)
Saxitoxin