September 11, 2004
• First life on earth approximately 3.5 million years ago.
• The first cells were prokaryotic, bacteria-like organisms.
• Eventually produced eukaryotic cells through endosymbiosis.
• Endosymbiosis is a symbiosis in which the symbiont lives in a host. It is thought that one
prokaryote came to live in another and the internal symbiont eventually became organelles
such as mitochondria.
• Mitochondria are the cells' power sources. They are distinct organelles with two membranes.
Usually they are rod-shaped, however they can be round. The outer membrane limits the
organelle. The inner membrane is thrown into folds or shelves that project inward.
What is a protozoan?
• A protozoan is a complete organisms in which all activities are carried on within the limits of a
single plasma membrane.
• There are over 64,000 species that have been named – over half of these from fossils.
• They are complex because their various organelles tend to be more specialized than those of
an average cell in a multicellular organism.
• Particular organelles may perform as skeletons, sensory structures, conducting mechanisms
and feeding structures.
Where might you encounter one?
• Protozoa are found where life exists. They are highly adaptable and easily distributed from
place to place.
• They require moisture.
• They may be free swimming or sessile
• Some species may have spanned geological eras of more than 100 million years.
How are they associated with the animal kingdom?
• All unicellular organisms used to be lumped together under kingdom Protista.
• Recent studies have suggested that combining all unicellular eukaryotes with the unicellular
algae into one kingdom was sloppy.
• Some are animal-like
• Some are free living, some commensalistic and some parasitic.
Why are they here…what do they contribute?
• Biological contributions:
– Intracellular specialization
– Division of labor between cells
– Asexual reproduction
– True sexual reproduction
– Simplest reflexes and instincts represented
– All types of nutrition
– Basic enzyme systems
– Well developed forms of aquatic locomotion
Characteristics of protozoan phyla
• Unicellular – but some with multicellular stages in their life cycle.
• Mostly microscopic
• All symmetries represented
• No germ layer present
• No organs or tissues but specialized organelles
• Locomotion by falsefeet, flagella and cilia
• Some with endo or exoskeleton but most naked
• All types of nutrition
• Land or water habitats
• Asexual or sexual reproduction
How do they get around?
• Locomotor organelles
– Protozoans employ cilia, psuedopodia or flagella for locomotion
– Rather large, blunt extensions of the cell body containing both central, granular endoplasm
• Filipodia are thin extensions, usually branching and containing only ectoplasm
• Axon = axis
• Podon = small foot
• These are long, slender, somewhat permanent pseudopodium found in certain sarcodine
• 1. Protozoa that move and capture food by forming pseudopods.
• A microscopic hair like process extending from the surface of a cell or unicellular organism.
Capable of rhythmical motion, it acts in unison with other such structures to bring about the
movement of the cell or of the surrounding medium.
What and how do they eat?
• Autotrophs – make their own food
• Hetertrophs – must have organic molecules synthesized by other organisms.
• Ingest visible forms (phagotrophs) of foods and soluble forms (osmotrophs).
• Phagocytosis: surrounding food particle.
• Osmoregulation – function of one or more of the contractile vacuoles. Usually located in the
ectoplasm, they act as a pump to remove excess water from the cytoplasm.
• Some have cytopyge which is a chracteristic structure for excretion of wastes.
How do they reproduce?
– Fission – division of body into two or more parts
– Budding – outgrowth of the parent that separates and is smaller than the parent – then
grows to adult size.
– Multiple fission or schizogony – numerous individuals produced simultaneously
– Sporogony – when multiple fission leads to spore formation.
• Gametic meiosis – not yet
• Zygotic meiosis – not yet
• Intermediary meiosis – not yet
• Syngamy - The fusion of two gametes in fertilization.
• Autogamy – self fertilization
• Conjugation - A process of sexual reproduction in which ciliate protozoans of the same
species temporarily couple and exchange genetic material
• Retorqueo = to twist back
• Monas = single unit
• Mitochondria and golgi bodies lacking
• Three anterior and one recurrent (running toward posterior) flagellum lying in a groove
• Intestinal parasite
What is a Golgi Body?
• n : a net-like structure in the cytoplasm of animal cells (especially in those cells that produce
• Diploos = double
• Monas = unit
• One or two groups of kinetosomes with a nucleaus
• Individual mastigonts with one to four flagella
• Mitotic spindle within nucleus
• Cysts present
• Free living or parasitic
What is a mastigont?
• Also called kinetid
• The kinetid (or mastigont) consists of the basal bodies and all of their appendages (striated
fibres and microtubule bundles).
• In ciliates the mastigonts typically consist of:
• a pair of basal bodies positioned one anterior to the other,
• a striated fibre (called the kinetodesmal fibre that is attached to the posterior basal body, and
which extends anteriorly and the the cells right.
• a transverse microtubule bundle that extends from the posterior basal body to the cell's left a
posterior microtubule bundle that extends posterior and upward to the cell's right from the
posterior basal body.
• Two karyomastigonts each with four flagella, one recurrent; with variety of microtubular bands
• Example: Giardia.
• Axon = axle
• Stylos = stake
• With an axostyle made of microtubules
• Para = beside
• Basis = base
• Refers to parabasal body = Golgi
• With very large Golgi bodies associated with karyomastigont
• Up to thousands of flagella
• Trichos = hair
• Monas = unit
• Typically at least some kinetosomes associated with rootlet filaments
• Parabasal body present
• Division spindle extranuclear
• Hydrogenosomes present
• No sexual reproduction
• True cysts rare
• All parasitic
• Example: Trichomonas
• Eu = true
• Glene = cavity or socket
• Zoon = animal
• With cortical microtubules
• Flagella often with paraxial rod
• Mitochondria with discoid cristae
• Mucleoli persist during mitosis
• With pellicular microtubules that stiffen pellicle
• Two heterokont flagella (flagella with different structures) arising from apical reservoir
• Some species with light-sensitive stigma and chloroplasts
• Example: Euglena
• Kinetos = to move
• Plastos = molded or formed
• With a unique mitochondrion containing a large disc of DNA
• Paraxial rod
• Trypanon = a borer
• Soma = the body
• One or two flagella arising from pocket
• Flagella typically with paraxial rod that parallels axoneme
• All parasitic
• Apex = tip
• Complex = twisted around
• Characteristic set of organelles associated with anterior end present in some development
• Cilia and flagella absent except for flagellated microgametes in some groups
• Cysts often present
• All parasitic
• Gregarius = belonging to a herd or flock
• Mature gamonts (individuals that produce gametes)
• Large extracellular oocysts within gametocysts
• Parasites of digestive tract of invertebrates
• Life cycle usually with one host
• Examples: monocystis and gregarina
• Monocystis Life Cycle
A. Feeding Trophozoite with host sperm tails on outer surface
B. Mating gamont pair
C. Gamonts producing gametes within gametocyst
D. Pairing of mating gametes to form zygotes
E. Haploid oocysts within gametocyst
F. Single oocyst with developing sporozoites
G. Mature oocyst with eight sporozoites
H. Oocyst shedding sporozoites
• Kokkos = kernal or grain
• Mature gamonts are small and typically inracellular
• Life cycle tpically with merogony, gametogony and sporogony
• Most species in vertbrates
• Examples: cryptosporidium
What is merogony?
• Merogony: development of an embryo by a process that is genetically equivalent to male
parthenogenesis and that involves segmentation and differentiation of an egg or egg fragment
deprived of its own nucleus but having a functional male nucleus introduced
• n : the development and maturation of sex cells through meiosis
• Gametogony = gamogenesis especially of protozoans
• Reproduction by multiple fission of a spore or zygote, characteristic of many sporozoans.
Sporogony results in the production of sporozoites.
• Note, two parasites in one bovine red blood cell.
• The vector for Babesia is typically a tick.
• In cattle this parasite causes disease known as Texas Cattle Fever or red-water fever.
• The disease can kill cattle within a weak.
• Cillium – eyelash
• Phora – bearing
• Cillia or cilliary organelles in at least one stage of life cycle
• Two types of nuclei
• Binary fission across rows of cilia
• Budding and multiple fission
• Sexuality involving conjugation and autogamy
• Nutrition hetertrophic
• Has contractile vacuole
• Most species free living, many commensal, some parasitic
• Examples: Paramecium
• paramecium is a ciliated single celled creature.
• The various species of paramecium can be distinguished from other ciliates by their cigar or
slipper shape and the undulating membrane within the peristome - a furrow that leads to the
cytostome, where food vacuoles are formed.
• Most paramecia are quite large for protozoa, approx. 0.5 mm long
• It is a very interesting, stalked ciliate with an inverted bell shape. The stalk contains a
contractile fibril called a myoneme. When stimulated, it shortens, causing the stalk to
coil like a spring.
• Vorticella usually anchor themselves to small particles of material however, it is not
uncommon to see them free swimming. When they undergo fission, they split along the
longitudinal axis in a process called budding. When they finally split apart, one keeps
the myoneme and the other free swims away and grows its own. The main purpose for
the cilia at the top is to sweep food down into the gullet.
• Stentor is a very large ciliate measuring from 500-2000 microns long when extended.
• Stentor coeruleus is a very large trumpet shaped, blue to blue-green ciliate with a
macronucleus that looks like a string of beads (dark connected dots on the left). With
many myonemes, it can contract into a ball. It may also swim freely both extended or
• Dinos = whirling
• Flagellum = little whip
• Typically with two flagella, one transverse and one trailing
• Body usually grooved transversely and longitudinally
• Chromoplasts usually yellow or dark brown, occasionally green or blue-green bearing
chlorophylls a and c
• Nucleus unique among eukaryotes in having chromosomes that lack or have low levels of
• Mitosis intranuclear
• Body form sometimes of spherical unicells, colonies or simple filaments
• Sexual reproduction present
• Members free living, and planktonic, parasitic or mutualistic
• Examples: zooxanthella, ceratium, noctiluca
• Zooxanthellae are best known for their role in the life of reef-forming corals. In tropical waters
almost all coral animals contain a colony of zooxanthellae. Without these symbiotic plants, the
coral animals would be unable to obtain enough nutrients to build their calcium carbonate
skeletons, which accumulate to form the vast coral reefs of the tropics.
• Noctiluca scintillans, commonly known as the seasparkle.
• a dinoflagellate, a little single-celled algae. Floating in swarms of millions these organisms
cause the glowing of the sea.
• The archetype of a dinoflagellate has a flattened spherical body shape and is armoured by
plates covered with an intricate texture. They propel themselves with two (or sometimes more)
flagella. One is pointed downward, the other is running as a spiral through a groove running
along the equator of the cell. Noctiluca however has a different body plan. It forms a gas bag
that enables the creature to float right under the surface of the ocean. There still are two
flagella although one is exceptionally thick.
• elegant shape, which makes it easy to identify. The cell 'body' has 'arms' more or less
developed in accordance with each sub-species. They are used as floats but they surely
create a great resistance to motion in water and this species doesn't move too quickly.
• Informal grouping
• Move by pseudopodia or locomotive protoplasmic flow without discrete pseudopodia
• Flagella usually restricted to development or other temporary stages
• Body naked or with external or internal test or skeleton
• Asexual reproduction by fission
• If sexuality present, usually associated with flagellated gametes
• Most free living
• Locomotion by lobopodia, filopodia or by protoplasmic flow without production of discrete
• The Arcella is a small amoeba that lives in a light brown or transparent chitinous "test"
• It is dome like on the top and concave on the bottom. They are from 50-200 um wide.
• Pseudopods extend out from the shell and are used for locomotion.
• Locomotion by reticulopodia
• Includes foraminiferans
• Examples: globigerina
• Locomotion by axopodia
• Includes radiolarians
• Chloros = green
• Phyton = plant
• Unicellular and multicellular algae
• Contains photosynthetic pigments of chlorophyll a and b
• Mostly free-living photoautotrophs
• Reserve food is starch