Invertebrate Zoology: Protozoa

-formerly Kingdom "Protista"
-live individually or in small simple colonies
-microscopic
-single-celled Eukaryotic organisms
-range of autotrophic to heterotrophic
~40,000 living, ~82,000 total
-not simple - so much so that some don't want to call them single celled
-at a protoplasmic level/grade (said when we could not describe the insides of cells)
-not really animals because some possess chlorophyll
-typically motile
-may live in freshwater, marine water, estuaries, sewage, lagoons, your gut, moist soil
-do not die when frozen

-approximately 2-200um
1. Smallest - blood parasites
2. Largest - Opalina - ciliates (gut symbionts)
3. Constraints - rate of diffusion, and swimming velocity

1. Density - # of particles present (weight/unit volume)
2. Viscosity - sticky/adherence - intermolecular forces that inhibit movement
3. Reynolds # - the ratio of inertial forces to viscous forces in a fluid medium

The ratio of inertial forces to viscous forces in a fluid medium
Re=pLU/V
where:
p=density of fluid
L=Body length
U=relative velocity of fluid
V=viscosity of fluid

Life at low Reynolds numbers:
Fish Swimming: Re=10²
Human Swimming: Re=10⁴
Protozoa Swimming: Re=10^-4
Consequences... low Re= increase in V compared to pLU --- virtually no inertial force

-Plasmalemma (cell membrane)
-Engine of Motion (proteins) - like muscle
-Acto-Myosin
-Tubulin-Dyein
-Possess organelles to carry out complex functions
-> out of this group comes animals - same characteristics as vertebrate muscles
-Support Mechanism (pellicle, test, lorica)
-Sensory/Defense Structures
-Ciliates - Extrusomes, Trichocysts, Mucous Threads
-Euglenozoa - Stigma/Eyespot
-Muller Visicle in Loxodes sp. --called Statolith -- function is gravity sensor, responding to weak gravitational field
-Locomotion - flagella, cilia, pseudopodia, gliding motility
-Nutrition - Cytosome and Food Vacuoles
-Water Balance - Contractile Vacuoles
-Respiration - cell membrane

-flagella=long Undulipodium
-present in Flagellates (Euglenozoa, Dinoflagellates, Trypanosomes, Giaridia)
-Built on 9+2 microtubules (tubulin protein plus dynein arms)
-arise from Kinetosome/Basal Body - provides energy
-conserved structure - both cilia and flagella
-irregular, spiraling or corkscrew movements (motion vector)
-eg. Trypanosomes = flagella + membrane
-Mosquito borne
-African Sleeping Sickness
-eg. Spasmoneme (stalk)
-built like a cable - of contractile fibers
-results-jerky movements
-Vorticella sp.

-cilia=short undulipodium
-present in ciliates (Ciliophora)
-Identical to flagella - only shorter
-kinetosomes connected by kinetodermal fibers
-allows for coordination - smooth movement - metachronal waves
-infraciliature - or kinety =ciliary rows
-Cirri (Cirrus sl.) = clusters of cilia *leg like function in hypotirchs and others

-for locomotion AND FEEDING
4 Types:
-Lobopodium (Pseudopodia)
-Filopodia
-Reticulopodia (network)
-Axopodia (rigid filament)

Important Parts:
-sheering zone: area of shunted cytoplasm
-axial core: cytoplasm to be shunted
-ectoplasm: outer cytoplasm
-endoplasm: inner cytoplasm

-cysts (Sporozoite) - passive, host agent
-polar filament (Microsporidian)
-Cliding Motility (Plasmodium and Toxoplasma)

-pseudopodia (Entamoeba)
-flagella and undulating membranes -- Plasmodium (Malaria)
-cysts (Sporozoite)
-Polar Filament (Microsporidian)
-Gliding Motility* (Plasmodium and Toxoplasma)

-cytosome- where feeding takes place, mouth-like, ciliates
-autotrophs -> self feeding
-heterotrophs -> eat others
-holozoic -> eat pieces of food
-saprozoic -> absorb nutrients across cell membrane - molecular level (<0.45 um when bacteria are ~10um, protozoa ~10-50 ->200um)
-Chlorophyta- Autotrophs (green algae)
-Amoeba- like animals
-phagocytosis - cell eating
- pinocytosis - cell drinking
-Apicomplexa - Parasites

-contractile vacuoles
-hypertonic, hypotonic to surroundings
-parasites - isotonic
-elininations - cytoproct, anal pore

-across cell membrane

-many ways

-asexual
-binary fission
-budding (sessile organisms)
-multiple fission
-schizogony - syncytium (multiple nuclei) - allows rapid division - population growth
-sporogony - multiple fission preceded by union of gametes

-sexual
-union of gametes - exchange of nuclear material
-isogametes - same sizes
-anisogametes - different sizes -- leads to sperm egg idea

-encystment vs excystment
-during harsh environmental conditions
-build a thick coat - encystment -- highly resistent
-conditions favorable - break the coat - Excystment

Cryptosporidium
Kentrophoros
Zooanthella - Dinoflagellates
Euplotes - Chlorella associates
Trichonympha
Giardia lamblia - "Beaver Fever"
Entamoeba histolytica - Dysentery