Animal like protists

1. Animal-like Protists

2. Core Concepts
Animal-like protists usually are unicellular
eukaryotic organisms. The absence of choroplasts
and chlorophyll distinguishes these organisms from
plant-like protists. Most protozoans are microscopic
in nature and are seen usually in freshwater
environment.

3. There are four major groups of protists based
primarily on their modes of locomotion/movement:
ciliophora (cilia-bearing), zoomastigina (flagella-
bearing), sporozoa (in fluids as parasites) and
sarcodina (with pseudopodia)

4. Different modes of reproduction are present in
animal-like protists namely: binary/longitudinal
fission, conjugation and fragmentation. Animal
muticellularity also evolved in one of these groups
exemplified by the choanoflagellate.

5. Movement is key to Identification
THERE IS NO PROTOZOAN THAT IS NOT
MOTILE!!!!!

6. PROTOZOAN VS METAZOAN
Proto- first; Zoa- animal
Meta – after; zoa- animal

7. Keywords
•Ciliophora anal porechoanoflagellate
•Cilliate food vacuole sarcodina
•Cilium/ciliacontractile vacuolepseudopod
•Paramecium Zoomastigina amoeba
•Trichocyst flagellum/flagellavector
•Macronucleusflagellatehost
•Micronucleussporozoaconjugation
•Gullet pelliclebinary fission

8. Phylogeny
Most recent ancestral stock of members of Animal
Kingdom
Genetic make-up is not the basis
What characteristic was used?

11. Protozoa
No cell wall
Have one motile stage
Mostly ingest food
Unicellular
Niche is limited
At least 10000 species are symbionts

13. Locomotion

14. Cilia and Flagella
Axoneme- made up of
9 external pairs
surrounding an
internal pair
Outside the cell
Kinetosome- internal
part of both structures

15. Pseudopodia- an extension for movement

16. Other forms of Pseudopodia
Lobopodia- large and blunt
extensions
Filopodia- thin and usually
branching
Reticulopodia- forms a net-like
mesh
Axopodia- long and thin,
supported by axial rods of
microtubule
Homework: what are the
different classifications of
Sarcodines? Give examples.

17. Nutrition-Phagocytosis vs Pinocytosis
Holozoic feeders, or
phagotrophs,
ingest particles of
food.
Food vacuole – the
membrane-bound
vesicle containing the
food.
Food vacuoles fuse
with lysosomes
containing digestive
enzymes.

18. Nutrition
Often, the site of phagocytosis is a definite
mouth structure, the cytostome.

19. Nutrition
Saprozoic feeding
(ingestion of soluble
food) may be by
pinocytosis or by
transport of solutes
across the cell
membrane.

20. Excretion and Osmoregulation
Contractile vacuoles function in
osmoregulation and excretion
More common in freshwater

21. Trichocyst
Organelle in ciliates
and dinoflagellates
that releases a
filamentous and
netlike protein to trap
food

22. Reproduction
Fission is the cell
multiplication process in
protozoa.
Binary fission – one
individual splits into two
equal sized individuals.
Budding – progeny cell
much smaller than parent.
Multiple fission – multiple
nuclear divisions followed by
multiple cytoplasmic
divisions producing several
offspring.

23. Reproduction
All of above accompanied by some form
of mitosis.
Mitosis in protozoa divisions varies from
metazoan mitosis.
Nuclear membrane often persists.
Spindle may form within the nuclear membrane.
Centrioles not observed in ciliates.
Macronucleus of ciliates elongates, constricts, and divides without
mitosis (amitosis).

24. Reproduction
Many types of protists reproduce sexually as
well as asexually.
Isogametes – all look alike.
Anisogametes – two different types.
Syngamy – gametes from two individuals fuse
to form the zygote.
Autogamy – gametes from one individual
fuse.
Conjugation – gametic nuclei are exchanged.

25. Cysts
Many protists are
able to survive harsh
conditions through
the formation of
cysts, dormant
forms with resistant
outer coverings and a
shutdown of
metabolism.

26. Major Protozoan Taxa
After the eukaryotic cell
evolved, diversification
followed, resulting in many
clades.
Opisthokonta is a very
large clade characterized by a
combination of flattened
mitochondrial cristae and
one posterior flagellum on
flagellated cells.
Includes animals, fungi,
chaonoflagellates and
microsporidians.

27. Stramenopila
The clade Stramenopila includes several
groups of heterotrophs as well as certain
groups of algae.
Most stramenopiles have a “hairy” flagellum
paired with a “smooth” flagellum.

28. Stramenopila
Water molds, diatoms, golden algae, brown
algae.

29. Euglenozoa
Phylum Euglenozoa is a
diverse clade that includes
predatory heterotrophs,
photosynthetic autotrophs,
and pathogenic parasites.
Kinetoplastids & Euglenids.
Persistence of nucleoli
during mitosis.
Cell membrane contains
microtubules to stiffen it
into a pellicle.

30. Euglenids
Euglenids have one or two flagella that emerge from a
pocket at one end of the cell.
Contain chloroplasts surrounded by a double membrane –
may have arisen by secondary endosymbiosis.

31. Kinetoplastids
Kinetoplastids have a
single, large
mitochondrion that
contains an organized
mass of DNA called a
kinetoplast.
Include free-living
consumers of bacteria in
freshwater, marine, and
moist terrestrial
ecosystems.
Others are parasitic.
Trypanosoma

32. Diplomonads
Diplomonads:
Are adapted to anaerobic environments.
Lack plastids.
Lack mitochondria but may have mitochondrial genes in
the nucleus.
Diplomonads have two nuclei and multiple flagella.
Giardia

33. Retortamonads
Phylum Retortamonada includes commensal and
parasitic unicells.
Lack mitochondria & Golgi

34. Alveolata
Members of the clade
Alveolata have
membrane-bounded
sacs (alveoli) just
under the plasma
membrane.
Dinoflagellates,
apicomplexans,
ciliates.

35. Alveolata - Ciliates
Members of the
phylum
Ciliophora use cilia
to move and feed.
Ciliates have large
macronuclei and
small micronuclei.

36. Alveolata - Ciliates
Ciliates are a large, varied group of protists.

37. Alveolata - Ciliates
Ciliates are structurally complex.
All ciliates have a kinety system made up of the
cilia, kinetosomes and other fibrils.
Many have structures that can be expelled such
as trichocysts and toxicysts.
Defensive function

38. Alveolata – Types of Ciliates
Suctorians – ciliates that lose cilia as adults, grow a
stalk and become sessile.
Use tubelike tentacles for feeding.
Symbiotic ciliates – some commensal, others
parasitic.
Free-living ciliates – may be swimmers, or sessile.
Stentor, Vorticella, Paramecium

39. Alveolata – Reproduction in
Paramecium
Paramecium, as well
as many other
protists, reproduce
asexually by binary
fission.

40. Alveolata – Reproduction in
Paramecium
Conjugation is a
sexual process that
produces genetic
variation.
Conjugation is
separate from
reproduction
which generally
occurs by binary
fission.

41. Alveolata – Dinoflagellates
Phylum Dinoflagellata is a diverse group of
aquatic photoautotrophs and heterotrophs.
Abundant in both marine and freshwater
phytoplankton.

42. Alveolata – Dinoflagellates
Each has a
characteristic shape
that in many species
is reinforced by
internal plates of
cellulose.
Two flagella make
them spin as they
move through the
water.

43. Alveolata – Dinoflagellates
Rapid growth of
some dinoflagellates
is responsible for
causing “red tides,”
which can be toxic to
humans.
California Noctiluca Bloom
http://www.whoi.edu/redtide/index.html

44. Alveolata – Dinoflagellates
Some
dinoflagellates
are
bioluminescent.
Others live
symbiotically
with corals
(zooxanthellae).

45. Alveolata – Apicomplexans
Apicomplexans are
parasites of animals and
some cause serious
human diseases.
Named because one
end, the apex, contains
a complex of organelles
specialized for
penetrating host cells
and tissues.
Have a non-
photosynthetic plastid,
the apicoplast.

46. Alveolata – Apicomplexans
Most
apicomplexans
have intricate life
cycles with both
sexual and asexual
stages that often
require two or more
different host species
for completion.

47. Parabasalids
Parabasalids move by means of flagella and
an undulating part of the plasma membrane.
This clade may have diverged from the main
eukaryotic clade very early.
Trichomonas

48. Amebas
Amebas are found
in fresh and salt
water as well as moist
soil.
An ameba feeds by
wrapping a
pseudopod around its
food – phagocytosis.

49. Nonactinopod Amebas
Nonactinopod
amebas include
amebas that form
lobopodia, filipodia
or rhizopodia.
Mostly heterotrophic
and actively seek and
consume bacteria and
other protists.

50. Entamoebas
Entamoebas are parasites of vertebrates and some
invertebrates.
Entamoeba histolytica causes amebic dysentery in humans.

51. Granuloreticulosa
This clade has slender
pseudopodia that extend
through openings in the
test, then branch and
run together forming a
net.
Foraminiferans, or
forams are named for
their porous, generally
multichambered shells,
called tests.

52. Granuloreticulosa
Pseudopodia extend through the pores in the test.
Foram tests in marine sediments form an extensive
fossil record.

53. Actinopod Amebas
Actinopod amebas form a polyphyletic group.
Radiolarians are one type of actinopod ameba.
They have very diverse and beautiful forms.

54. Actinopod Amebas
The pseudopodia of radiolarians, known as
axopodia radiate from the central body.

55. Phylogeny and Adaptive Diversification
Phylum Chlorophyta
Phylum Retortamonada
Class Diplomonadea
Order Diplomonadida
Phylum Axostylata
Class Parabasalea
Order Trichomonadida
Phylum Euglenozoa
Subphylum Euglenida
Class Euglenoidea
Subphylum Kinetoplasta
Class Trypanosomatidea
Phylum Apicomplexa
Class Gregarinea
Class Coccidea
Phylum Ciliophora
Phylum Dinoflagellata
Amebas
Rhizopodans
Granuloreticulosans
Actinopodans

56. Choanoflagellate
Collared flagellates
One apical flagellum surrounded by
30-40 microvilli
Closest relative of animals
Mitochondrial genome suggests that
choanoflagellates are an outgroup of
metazoans

57. Choanocyte of sponges