1. Protozoa I

4. Over 50,000 known species 45 phyla (more than metazoa!)
Protozoans
Over 50,000 known species
45 phyla (more than metazoa!)

5. Relationship to Other Organisms
Two Kingdoms – Arististotle, Linnaeus
Plants
Metaphyta
Protophyta
Animals
Metazoa
Protozoa
Lots of problems with this scheme
Problems:
Not a phylogenetic dichotomy
No phylogenetic relationships among the taxa within each group
The two kingdoms are not really distinguishable
Some organisms have characteristics of both kingdoms
ex. Dinoflagellates – some get 5% of energy from photosynthesis and the rest from heterotrophic digestion of consumed materials; some can change affiliation by being kept in the dark for 24 hours.
Some organisms are one, both or neither

6. Relationship to Other Organisms
3 kingdoms of Haeckle/Darwin
Plants
Animals
Protists
Took care of the little stuff seen with the early microscopes
Still has problems
Problems:
Not a phylogenetic dichotomy
No phylogenetic relationships among the taxa within each group
The two kingdoms are not really distinguishable
Some organisms have characteristics of both kingdoms
ex. Dinoflagellates – some get 5% of energy from photosynthesis and the rest from heterotrophic digestion of consumed materials; some can change affiliation by being kept in the dark for 24 hours.
Some organisms are one, both or neither

8. Relationship to Other Organisms
Copeland’s Four-Kingdom System (1938)
Kingdom Monera.
Kingdom Protoctista or Protista (priority?).
Protozoa
Red and brown algae
Fungi
Kingdom Plantae
Green algae
Kingdom Animalia

9. Relationship to Other Organisms
Whittaker – 1960’s
Added Kingdom Fungi
5 Kingdoms
Kingdom Animalia
Kingdom Plantae
Kingdom Fungi
Kingdom Protista
Kingdom Monera - Prokaryotes
Eukaryotes
Apparent dichotomy between prokaryotes and eukaryotes

11. Kingdoms and Domains Carl Woese - U. of Illinois (1970’s-present)
Studied gene sequences of bacteria, archaea, and eukaryotes
Found fundamental differences (major!)

12. Relationship to Other Organisms
Carl Woese – late 1970’s
Archaea NOT Archaebacteria
Biochemistry is different from bacteria
More closely related to animals than they are to bacteria
Briefly had six kingdoms with Archaea and Eubacteria replacing the Monera
Changed to three domains
Eubacteria
Archaea
Eukarya
Prokaryotes

13. 6 Kingdoms of Life
3 Domains of Life

15. Figure 1: All organisms are connected by the passage of genes along the branches of the phylogenetic Tree of Life.
Figure 2: Living organisms sit like leaves at the tips of the branches of the Tree of Life. Their evolutionary history is represented by a series of ancestors which are shared hierarchically by different subsets of the organisms that are alive today.

16. Relationship to Other Organisms
Protista or Protoctista
Some algae (red, most green algae are not included)
Protozoa
Traditionally classified based on how they move: amoebae, flagellates, ciliates, sporozoans
Has changed recently to also contain:
Some slime molds
Aquatic “molds”

17. Old system classified by locomotion
Ciliophora (=Ciliata, ciliates) a clade Hypotrichs, holotrichs, heterotrichs, suctorians
Apicomplexa- (=Sporozoa) a likely clade Gregarina, Coccidia – includes many important parasites
Mastigophora (=flagellates) a functional group Excavates, Kinetoplastids, Parabasalids, Choanoflagellates, Dinoflagellates (some are important parasites)
Sarcodina (=amoebas) a functional group Amoebozoa, Foraminifera, Actinopoda (Radiolaria, Heliozoa) (many are important geologically)

18. Protozoan Phylogeny Problem Protozoa is a polyphyletic group
Multiple ancestors rather than a single ancestral protozoan
Aim is to establish monophyletic groups that have a single ancestor

19. Protozoan Phylogeny Reclassification based on Life History
Ultrastructure
Biochemistry
Molecular data including DNA sequencing
Most trees are being constructed based on molecular data
May or may not be the “best” way to go
Dissenting camps: role of lateral gene transfer, choice of genes for sequencing, convergent evolution, etc.

20. Relationship to Other Organisms
Protista – still used as teaching tool.
Grades 7-12?
Undergrad intro bio (with reservations)
We will not discuss Protists!
Instead, note the following schemes:
First - breakdown of what used to be protists.
Second - taxonomic groupings of organisms covered in Ch 3 (pg 71ff).
Focus on those covered in text and/or lab

21. Eukaryote classification is in flux
The major clades are not yet sorted out – but there is rapid progress
Based on cell structural features, there are about 60 different named eukaryote taxa according to Patterson (Tree of Life)
These have been sorted into 8 clades based on molecular & structural data by Baldauf 2003 (Science 300:1703)

22. Kingdom Chromista The Alveolata
Flattened membranous alveoli (sacs) under outer cell membrane

24. The Alveolates Phylum Ciliophora Phylum Dinozoa (Dinoflagellata)
Phylum Apicomplexa

25. The Rhizaria Very diverse group based on molecular data
Tubular cristae
3 Phyla
Phylum Foraminifera
Phylum Radiolaria
Phylum Cercozoa

26. The Heterokonta Phylum Stramenophiles
Heliozoans? – probably polyphyletic
Class Opalinata
Flagellated parasites of intestines of ectothermic vertebrates

27. Kingdom Protozoa The Amoebozoa Branching, tubular cristae
Lobose pseudopodia
Arcellanids
Xenophyophoreans
Phylum Mastigamoididae
Phylum Eumycetozoa

28. The Excavata Disc-shaped mitochondrial cristae
Deep ventral feeding groove (hence excavate)
Phylum Parabasala – no mitochondria
Class Trichomonadida
Class Hypermatigia

29. Phylum Euglenozoa
Class Euglenida
Order Kinetoplastea

30. Phylum Heterolobsea
The diplomonads – no mitochondria
The oxymonads

31. The Opisthokonta Phylum Choanomonada Phylum Fungi Phylum Microsporidia
The Myxozoans – probably degenerate cnidarians
Phylum(?) Animalia

32. Defining Characteristics of “Protozoa”
1674 Antonie van Leeuwenhoeke
Nearly ubiquitous –wherever there is water
Soil
Water
On/in plants and animals
Life styles
Free-living
Symbioses
Mutualists
Parasites

33. Antonie van Leeuwenhoeke

35. Things that animals do (and protozoa too)
Move (at some stage in the life cycle)
Obtain food and digest it
Obtain oxygen
Maintain water and salt balance
Remove metabolic wastes
Reproduce
Sense and react to the environment

36. Defining Characteristics of “Protozoa”
Haeckel coined the termed Protista
Protist was anything that wasn’t clearly plant or animal
Now it’s anything that isn’t plant, animal, fungi or bacteria
Most are probably unknown
Over 84,000 species
½ of these are fossils (shelled forms)
No formal taxonomic category called Protista

37. Defining Characteristics of “Protozoa”
General characteristics highly variable
Size, morphology, ultrastructure
Nutritional mode, physiology
Behavior, life history
Importance
Ancestral to multicellular animals and plants (polyphyletic): ex. Choanoflagellates and sponges
Mutualists in other inverts: ex. dinoflag. in corals
Disease agents: ex. Plasmodium in malaria

38. Defining Characteristics of “Protozoa”
Importance
Disease agents
Model organisms
Ecology
Genetics
Physiology
Development

39. Defining Characteristics of “Protozoa”
Eukaryotic
Unicellular
Mostly small μm (0.5 μm – 7 mm)
Multicellularity in a few but this is a derived character
No collagen or chitin in cell walls
Heterotrophic
Ancestral state is non-photosynthetic
Photosynthesis in a few groups is a derived character
Most are motile (except Apicomplexa)
Stentor is up to 2 mm
Forams can reach 6-7 mm

40. Protist Bauplan - On Being Unicellular
Strategies and constraints of a Unicellular Bauplan
Size limitations
Body structure
Excretion
Gas exchange
Support and locomotion
Nutrition
Reproduction
Activity and sensitivity

41. On Being Unicellular Protozoa vs metazoa Protozoa are unicellular
Thought to be simplest form of life
BUT …
Protozoa are not simple!
A protozoan is more complex than any single metazoan cell
Very complex internal structure
Specialized organelles take the place of organs in metazoans
Protozoa vs metazoa
Proto means first so protozoa were thought to be the first animals
Meta means many so metazoans are multicellular animals
Single cell does all the things that are necessary for life
- intake/processing of energy and nutrients
- complex structurally
- response to stimuli
- locomotion (or transference to another host)
- reproduction using genetic code
- evolution

42. Urotricha globosa
Cothurnia annulata
Pseudodifflugia sp.
Halteria grandinella
Ctedoctema acanthocryptum
Vorticella aquadulcis

43. Stylonychia

44. Defining Characteristics of “Protozoa”
Similarity of structures does NOT imply relatedness
Could be convergent evolution
Various types of evidence are used in testing hypotheses regarding evolutionary relatedness
Gene sequencing
Cellular ultratructure

45. Size limitations Surface area to volume ratio
SA increases as radius squared
V increases as radius cubed
As cell becomes larger, diffusion becomes more and more difficult (~1 mm limit)
Need to have lots of complex projections etc. to increase SA
Need large SA/V

51. Body Structure Cytoplasm has two regions Ectoplasm Endoplasm
Next to cell membrane
Clear, stiff, gelatinous
Endoplasm
Inner portion
More fluid in nature

53. Body Structure Only one plasma membrane
Everything is inside that membrane
Structure is identical to the plasma membrane of all other multicellular organisms
High SA/V for protist cells
Membrane has fluid mosaic structure
Lipids and proteins can move about laterally within the membrane

54. Membrane has fluid mosaic structure

62. Body Structure
Internal structures
Cytoskeleton
Shape
Rigidity

63. Cytoskeleton
Myonemes

64. Cytopharynx Macronucleus
Cirri

65. Body Structure Outer coverings - give shape/support/protection
Pellicle
Interlocking strips of protein below plasma membrane in Euglenids
Gives cell shape and stability while permitting flexibility
Metaboly

66. Eugloid movement = metaboly

67. Body Structure
Lorica
Vase-shaped protective shell

68. Body Structure Test External “shell” Usually many parts
Plates are below plasma membrane (cellulose plates in dinoflagellates, various materials in testate amoebas)
CaCO3 foraminiferans
Silica in radiolarians

70. Body Structure The usual eukaryotic organelles
May be more than one macronucleus
Runs everyday activities of cell
May be one or more micronuclei
Used for sexual reproduction
Some are anaerobes
Most have no mitochondria or cytochromes, and have an incomplete TCA cycle (tricarboxylic acid cycle)
Some contain hydrogenosomes-small membrane-delimited organelles containing a unique electron transfer system that uses protons as terminal electron acceptors to form molecular hydrogen
Trichonympha lives in the gut of termites
Giardia is an intestinal parasite

72. Mitochondria clockwise Paramecium Cryptomonad Euglena

73. Body Structure Some protozoa are anaerobes.
Trichonympha lives in the gut of termites
Giardia is an intestinal parasite
Most have no mitochondria or cytochromes, and have an incomplete TCA cycle (tricarboxylic acid cycle).
Some contain hydrogenosomes-small membrane-delimited organelles containing a unique electron transfer system that uses protons as terminal electron acceptors to form molecular hydrogen.
Some have symbiotic aerobic bacteria that do the job of TCA cycle for the host.

74. Body Structure Defense against predation
Change shape to become harder to eat.
Euplotes detects presence of predator
Chemically
Physically
Euplotes swells in middle and becomes too big for Lembadion to swallow
Fig. 2. a, b, A typically formed Euplotes (E) in, a, the mouth opening (M) of the predaceous ciliate Lembadion bullinum (L) and in, b, a food vacuole in the cytoplasm of the predator, c, Lembadion bulIinum (left) and the Lembadion-induced defensive form of Euplotes daidaleos (right). The defensive form of Euplotes is too bulky to be swallowed by Lembadion (differential interference-contrast; scale bar = 50 txm).

75. Body Structure Special organelles Contractile vacuoles
Osmoregulation in freshwater species

76. Contractile Vacuole Osmoregulation in FW

77. Contractile Vacuole Osmotic Regulation

80. Body Structure Special organelles Trichocysts Defense, prey capture
Mucus
Toxins
Adherence to prey (Didinium)

81. Gas Exchange No circulatory system All transport is by diffusion
Plasma membrane must remain moist for gases to diffuse
Restricts protozoa to moist habitats