Platythelminthes

Organization

Organ Lvel

Embryonic Development

Triploblastic

Protostomes

Acoelomates

Deutorstomes

Symmetry

Bilateral

Skeleton

Parenchyma fills blastocoel, provides hydrostatic skeleton

Movement

Hydrostatic Skeleton

Longitudinal Muscles in the mesoderm

Circular muscles in the mesoderm

Cilia on ventral surface

Sensory/Nervous

Cephalization, ventral nerve cord

Digestion/Feeding

Gastrovascular Cavity (GVC)

• Free living

• Ectoparasites

• Endoparasites

Excretory

Diffusion

Circulation

Diffusion

Respiration

Diffusion

Reproduction

• Asexual (Regeneration)

• Sexual monoecious (Hermaphroditic)

- Internal fertilization

• Penis-fencing (Class Polycladida)

Classes of Platyhelminthes

• Tricladida

• Trematoda

• Cestoda

• Polycladida

• Monogenea

Class Tricladida

• Planaria

• Triply-branches intestine

• Free living omnivores

• Protruding pharynx to feed

• Ocelli (eyespots)

• Auricles (chemosensory receptors)

What organism is this? Class and Phyla? Identify the labelled parts below.

• Planaria

• Phylum Platyhelminthes

• Class Tricladida

A. Ocelli (eyespots)

B. Auricles (Chemosensory receptors)

C. Gastrovascular cavity (GVC)

D. Pharyngeal cavity

E. Pharynx

F. Mouth

G. Diverticulum of GVC

Polycladida

• Almost all marine

• Elongated Branching intestine

• Free living

• Brightly colored and toxic

• Penis-fencing

Class Trematoda

• Flukes

• Endoparasites

• Lack sensory and locomotor functions of planaria

Two suckers

i. Oral sucker for feeding

ii. Ventral for attachment

What phylum and class is this organism? Identify the parts with their corresponding letter.

Phylum Platyhelminthes

Class Trematoda

A. Oral sucker

B. Pharynx

C. Intestine

D. Ventral sucker

E. Uterus

F. Seminal Receptacle

G. Excretory Bladder

H. Testes

I. Ovary

J. Yolk glands

Class Monogenea

• Ectoparasites of fish

• Single host in life cycle

Cestoda

• Tapeworms

• Endoparasites

• No gut; absorb nutrients through cuticle

What phyla and class does this organism belong to? Identify the parts that correspond to each letter.

• Phylum: Platyhelminthes

• Class: Cestoda

A. Rostellum

B. Hooks

C. Suckers

D. Scolex

What phyla and class does this organism belong to? Identify the parts that correspond to each letter.

• Phylum Platyhelminthes

• Class: Cestoda

A. Vitelline Gland

B. Genital Pore

C. Sperm Duct

D. Testes

E. Excretory Canal

F. Ovary

G. Uterus

What phyla and class does this organism belong to? Identify the parts that correspond to each letter.

• Phlyum: Platyhelminthes

• Class: Tricladida

A. Mesoderm

B. Testis

C. GVC

D. Pharyngeal Cavity

E. Epidermis

F. Gastrodermis

G. GVCs

H. Pharynx

I. Cilia

J. Ventral nerve cord

K. Gland cell

L. Oviduct