1. Triploblastic

2. bilateral symmetry

3. flattened dorsoventrally

4. epidermis cellular or cyncytial (a syncytium)

   - Cellular: eg proglottids, etc. Each cell is separate, with 1 nucleus each

   - Cyncytial: when the membrane dissolves during development. Multiple nuclei in a syncytium. ← neodermata

5. no internal body spaces (ie acoelomate)

6. digestive system incomplete or absent in some (cestodes)

7. Pair of ganglia with longitudinal nerve cords

8. Simple sense organs; eyespots in some

9. Excretory system with protonephridia (or flame cells)

10. no respiratory, circulatory, skeletal systems. No need, especially if parasitic.

11. most hermaphroditic; internal fertilization

12. many parasitic, complicated life cycles

Kingdom: Animalia, Phylum: Platyhelminthes, Class: Turbellaria ('stirring') 

Common name: Free living flatworms; planarians

 Negatively phototactic (move away from the light)

Kingdom: Animalia, Phylum: Platyhelminthes, Class: Trematoda

Common name: Flukes, Opisthorchis, Schistosoma

Parasitic.

Morphologically, very similar to turbellarians, but can produce enormous quantities of eggs.

Life cycle involves 2 or more hosts.

What are the characteristics of Class Monogenea?

parasites primarily of fishes; have complex posterior attachment structure

Attachment structure called a opisthaptor.

1. no digestive tract.

2. Have head (scolex) and repeating series of body segments (proglottids)

3. Very, very fast reproduction.

4. Hermaphroditic

 Cysticercercosis: ingesting Taenia Solium (pork tapeworm) eggs directly (rather than eating infected pork)

Neurocysticercosis: If pork tapeworm gets into brain. Can be fatal

E. Granulosus

Tiny tapeworm that lives in coyotes, wolves, dogs, foxes, etc.

Does not harm the canine.

Eggs are passed in feces, are passed to moose, sheep, deer, etc.

Grow into larger and larger hydatid cysts (have a lot of water). Grow in liver.

If humans consume eggs from canine feces, can get it too. Can grow in livers, brains, eyes, etc

ribbon worms

• Cylindrical body with 3 germ layers

• An eversible proboscis

• A rynchocoel (small space) that houses proboscis

• Complete digestive system

• usually separate sexes, some fragmentation

• flame cells for excretion

• predators on invertebrates and eggs of invertebrates

What is a rhynchocoel and eversible proboscis?

Eversible Proboscis: (usually sharp-ended) tube/mouth. Can be retracted and extended.

Rhynchocoel: housing for eversible probiscis

Carcinonemertes—an egg predator on crabs

Female crabs end up with them; they eat eggs.

See Fig 14.12

Kingdom: Animalia, Phylum: Platyhelminthes, Class: Trematoda, Species: Opisthorchis sinensis

Common name: Chinese Liver Fluke

Adults live in bile duct of liver. Release eggs containing miracidium (larval form). Miracidium hatches after egg has been eaten by snail. They develop into redia and sporocysts. Developed larvae are released from snail as cercaria. They encyst, becoming metacercaria in the muscles of fish. We eat them, they develop into adults.

male and females mate inside humans. Eggs are released, develop into miracidium. Become sporocysts in snails. Developed cercaria are released, where they can infect people.

See fig 14.13b