1. Comparison of Prokaryotic and
Eukaryotic Cells
Component P E
Cell Wall P A/P
Centrioles A A/P
Chloroplasts PISC PISC
Cilia A PISC
Cytoskeleton A P
ER A P
Flagellum Oft. P PISC
Glycocalyx A P
GA A P
Lysosomes A P
Mitochondria A P
Nucleus A P
Plasmalemma P P
Ribosomes P P
Vacuoles P P
Vesicles P P

2. Endosymbiont Hypothesis
- Proposed by Lynn Margulis from
Boston University
AUTOTROPHIC HETEROTROPHIC
EUKARYOTES EUKARYOTES

5. SYMBIOTIC THEORY
The first multicellular organisms occurred from symbiosis of
different species of single-celled organisms, each with different
roles.

6. CELLULARIZATION OR SYNCYTIAL THEORY
A single unicellular organism could have developed internal
membrane partitions around each of its nuclei.

7. COLONIAL THEORY (proposed by Haeckel in 1874)
Symbiosis of many organisms of the same species led to
multicellular organism.

8. PARAZOANS (no true tissues) – sponges/porifers
PHYLUM PORIFERA (L. porus, pore + fera, to bear)

9. CHARACTERISTICS OF PHYLUM PORIFERA
1. Assymetrical or radially symmetrical

10. Verongia

11. Verongia

12. Adocia

13. CHARACTERISTICS OF PHYLUM PORIFERA
1. Assymetrical or radially symmetrical
2. Presence of the cell types: pinacocytes,
mesenchyme cells, and choanocytes

14. THREE CELL TYPES
a. PINACOCYTES – flat cells that line the outer surface of a sponge
POROCYTES – specialized pinacocytes that form contractile tubes
responsible for the regulation of water circulation in the
organism
b. CHOANOCYTES or COLLAR CELLS – flagellated cells that have
collarlike ring of microvilli surrounding a flagellum
Functions
1. Creation of water currents by flagellar movement
2. Filtration of microscopic food particles from the water
3. has reproductive function in that choanocytes have the ability
to form sperm and egg cells
c. MESENCHYME CELLS – found in the mesohyl (between the
pinacocyte and the choanocyte layers. Mesenchyme cells include
amoeboid cells that are specialized for reproduction, secreting
skeletal elements, transporting food, storing food, and forming
contractile rings around openings in the sponge wall.

16. CHARACTERISTICS OF PHYLUM PORIFERA
1. Assymetrical or radially symmetrical
2. Presence of the cell types: pinacocytes,
mesenchyme cells, and choanocytes
3. Central cavity, or series of branching chambers,
through which water is circulated during filter
feeding

22. CHARACTERISTICS OF PHYLUM PORIFERA
1. Assymetrical or radially symmetrical
2. Presence of the cell types: pinacocytes,
mesenchyme cells, and choanocytes
3. Central cavity, or series of branching chambers,
through which water is circulated during filter
feeding
4. No tissues or organs (parazoans)

23. PHYLUM CNIDARIA
Characteristics:
1. Individuals are either
solitary or colonies
2. Of two basic body types
a. polyp or hydranth – with a
tubular body having one
end closed and attached
and the other with central
mouth usually surrounded
by soft tentacles
b. medusa – free swimming
adult with gelatinous body
of umbrella shape, margined
with tentacles, and having
the mouth on a central
projection of the concave
surface

24. Cyanea arctica
Having tentacles up t0 33 feet
long

25. Sea anemones range from a few
millimeters to 1 meter in diameter

28. PHYLUM CNIDARIA
Characteristics:
3. Symmetry radial or biradial
about an oral-aboral axis; no
head or segmentation
4. Body of two layers of cells,
an external epidermis and
an inner gastrodermis, with
varying amount of mesoglea
in between
5. Cnidarians are characterized
with the presence of
nematocysts (stinging
capsules); nematocysts are
found either in both layers.
6. All are aquatic and nearly all
are marine

30. Chlorohydra viridissima
Has symbiotic zoochlorellae in its
inner cells Hydra oligactis
Has slender stalks and long
tentacles

31. EPITHELIOMUSCULAR CELLS – cells having a bulbous outer
portion and an elongate base containing a contractile fibril
placed against the mesoglea. These cells are responsible
for the shortening or contraction of hydra principally during
movement.
GLAND CELLS – tall cells that secrete a sticky mucus by
which hydras attach to objects in the water. These cells can
also produce gas bubble.
INTERSTITIAL CELLS - - small, round and undifferentiated
cells with large nuclei, found between the bases of
epidermal cells. They have the potential to produce all
other cell types. Such as cnidocytes and gametes.
CNIDOCYTIC CELLS – specialized cells that contain the
unique cnidarian stinging apparatus, the nematocyst.

32. NEMATOCYSTS are used for defense, locomotion or food capture.
a. Abundant in the tentacles, some occur throughout the epidermis, except on
basal disk

33. Obelia

35. Tubularia

39. 00863f28
Pelagia

40. Cassiopoeia
Order Rhizostomae

41. Chironex fleckeri or Order Cubomedusae

42. Haliclystus
Order Stauromedusae

45. Scyphistoma
(Aurelia polyp)

46. Aurelia strobila
Strobilation – type of transverse fission that involves
horizontal constrictions from around the body and deepen so
that the organism resembles a pile of minute saucers with
fluted borders, the edge of each being formed into eight
double lobes.

47. Strobilating polyp and ephyra

49. Metridium

53. Ephiactis

54. Boloceroides

55. Cerianthus