1

PH. PLATYHELMINTHES

* CLASSES:

1.

2.

3.

4.

1.

2.

3. GVC (Incomplete gut)

4. Dorsoventrally flattened

5. Bilateral symmetry

6.

7.

8. Excretory system ⇒

9. 2 mm ⇒ 10 M, ~20,000 spp., many parasitic

10. Complex reproductive & musculature systems

2

PH. PLATYHELMINTHES

* GENERAL BODY FORMS:

* BODY WALL & LOCOMOTION:1. Ciliary gliding2. Muscular undulations

3

PH. PLATYHELMINTHES* FEEDING:

1. PHARYNGES:A. Simple, non-eversible

B. Cylindrical, eversible

C. Ruffled (plicate), eversible

GVC

GVCGVC

GVC

GVC

4

PH. PLATYHELMINTHES

* FEEDING:

2. DIGESTION:A. Primary → extracellularB. PhagocytosisC. Final → intracellular

3. GASTROVASCULAR CAVITIES: GVCA. None

B. Simple sac

C. Convoluted

D. Tri-branched

E. Multi-branched

GVC

GVC

5

PH. PLATYHELMINTHES

* EXCRETION & OSMOREGULATION:

1. ProtonephridiaA. Ectodermal origin

B. 2-celled unit

C. Closed internally; open externally

6

PH. PLATYHELMINTHES

* NERVOUS SYSTEM:

1. Ladder-like or net-like

2. Cephalization

3. Ectodermal origin

4. INVERTED PIGMENT CUP OCELLUS

7

PH. PLATYHELMINTHES

REPRODUCTION:

ASEXUAL:1. Transverse fission

2. Regeneration

SEXUAL:1. Hermaphroditic

2. Mutual cross fertilization

3. Internal fertilization via hypodermic impregnation

ORGAN SYSTEMS (within same animal):

8

PH. PLATYHELMINTHES

ONTOGENY:

GVC

9

PH. PLATYHELMINTHES

LIFECYCLES:

1. CESTODA:(EXAMPLE: TAENIA)

adult tapeworm [sexual reproduction] human intestines

bladder worms zygotes [via proglottids]

oncosphere larva [living in cow]

10

PH. PLATYHELMINTHES

LIFECYCLES:

2. MONOGENEA:(EXAMPLE: ANAPLOCOTYLOIDES & DACTYLOGYRUS)

adult fluke[sexual reproduction]

gills of fish

swimming zygoteslarva

oncomiracidium larva [bottom of pond]

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PH. PLATYHELMINTHES

LIFECYCLES:

3. TREMATODA:(EXAMPLE: OPISTHORCHIS)

adult fluke[sexual reproduction] in human bile ducts

metacercarial cyst

[in fish muscle tissue]zygotes

cercaria larva

[free swimming]miracidium larva

[asexual redia in snail]

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PH. PLATYHELMINTHES

* PHYLOGENETIC CONTEXT & CHARACTER EVOLUTION: