11.3 Platyhelminthes

Question 1

Protostomes are…

Answer 1

• Triploblastic
• Blastores develop into mouth
• Anterior brain
• Ventral nerve cord
• Bilateria

Question 2

Other name for Platyhelminthes?

Answer 2

Flatworms

Question 3

Platyhelminthes - gut?

Answer 3

Blind

Question 4

Body plan of platyhelminhes?

Answer 4

Planarian - head, eyespots (photoreceptors), auricles (chemoreceptors), highly branched digestive cavity

Question 5

How do platyhelminthes take up O2?

Answer 5

Diffusion (highly flattened body): no respiratory or circulatory

Question 6

True or false - some have no digestive cavity or mouth

Answer 6

True. They have a higly branched digestive CAVITY

Question 7

Platyhelmintes - symmetry?

Answer 7

• Bilateral (because head)

Question 8

Directed movement is linked to ….

Answer 8

Cephaliztion

Question 9

What are the advantages of concentration of neurons and sensory structures at the anterior end?

Answer 9

• Enables directed motion and behaviour

- Senses encounter new environment first

Question 10

Sensory structures of platyhelminthes?

Answer 10

• Mechanoreceptors
• Chemoreceptors
• Photoreceptors

Question 11

Nervous system of platyhelminthes?

Answer 11

• Cerebral ganglion (concentratin of neurons, primitive brain)
• Longitudina nerve cords

Question 12

Free living platyhelminthes?

Answer 12

Turbellaria (planarian - can regenerate body, anterior and always develop into a head, reproduce asexually by fission &sexually)

Question 13

Parasitic platyhelminthes?

Answer 13

• Monogenea (ecto)
• Trematoda (endo)
• Cestoda (endo)

Question 14

Monogenea?

Answer 14

• Ectoparasites, flukes = flat body with suckers (on fish gills)

Question 15

Trematoda?

Answer 15

Endoparasites, flukes (primary - humans - and intermediate host - snail)

Question 16

Disease linked to trematoda?

Answer 16

Schistosomiasis (can damage internal organs and impair growth and development in children) - Asia, Africa, South America

Question 17

Cestoda?

Answer 17

Endoparasites, tapeworm

Question 18

Habitat of cestoda?

Answer 18

Intestines of vertebrates (host specific)

Question 19

Adaptations of cestoda?

Answer 19

• Scolex (suckers, hooks)

- Proglottids (reproductive segments)

Question 20

System of cestoda?

Answer 20

• No mouth or digestive system

Question 21

How cestoda passed?

Answer 21

• Protective cuticle forms around embryos and terminal proglottids break off, passed via feces