Phylum Platyhelminthes

Question 1

What species consists of the platyhelminthes?

Answer 1

• Flatworms (platy = flat … helminth = worms)

Question 2

What kind of body type do flat worms have?

Answer 2

they are aceolmate (lack coelom, therefore lack fluid filled body cavity)
- they are triploblastic

Question 3

How are their respiratory and circulatory functions?

Answer 3

• they don’t have a special circulatory or gas-exchange system
• their bodies have to be in contact with water and air to exchange gasses

Question 4

What is the digestive system of the playthelminthes?

Answer 4

• they don’t have a complete digestive system, they have a mouth and gut lumen but lack anus
• some kinds lack mouth and gut

Question 5

How do most platyhelminthes (flatworms) eat?

Answer 5

through a host… thats why they’re parasitic

Question 6

What are the 3 Classes of Platyhelminthes?

Answer 6

1. Class Turbellaria
2. Class Cestoidea
3. Class Trematoda

Question 7

What are the 6 characteristics of the class Turbellaria?

Answer 7

1. they are free living flatworms
2. they are mostly marine and predatory
3. their epidermis is covered by cilia
4. they have a pair of ventral nerve cords
5. they have a pair of ganglia (i.e. brain) at the front of the body
6. They do not have anal opening and their undigested food is ejected from their mouth

Question 8

What are 4 characteristics of Class Cestoidea?

Answer 8

1. They consist of tape worms
2. They are entirely endoparasitic (they live inside the host) and in the digestive systems of other animals
3. They Lack a digestive system and absorb nutrients through thin body wall
4. They have scolex which is that the front end of their body is modified for holding onto a host’s gut via suckers and hooks

Question 9

What are proglottids in tapeworms?

Answer 9

they are posterior to the scolex and its a long chain of units devoted to reproduction

• The new proglottids produced at the base of the scolex (what they use to hang on to the gut)
• older proglottids are towards the posterior end of their body
• mature proglottids are filled with eggs and the first host usually poops these eggs out

Question 10

What is the life cycle of the tapeworms?

Answer 10

it needs two hosts to complete its life cycle

• their eggs are consumed by the intermediate host which is a invertebrate and the parasite does not undergo sexual reproduction in the invertebrate
• then their larvae develop and stay in cysts inside the tissues of the intermediate host
• the intermediate host is then eaten by a final (definitive) host which is usually a vertebrate and the larvae develop into adult tapeworm in the gut of the final host and undergo sexual reproduction

Question 11

How do tapeworms effect humans?

Answer 11

humans can get tapeworms from undercooked pork and beaf from a strain called Taenia spp.

• tape worm can also be present in raw fish including salmon
• It causes blockage and nutritional deficiency

Question 12

What are 4 characteristics of the platyhelminthes class of Trematoda?

Answer 12

1. Their common name is “flukes” and they have 2 large suckers for attachment
2. they have a complex life cycle of 2 or more hosts and the adults are parasites of vertebrate and invertebrates serve as intermediate hosts
3. They have medical and economical importance
4. Blood flukes (schistosoma) –> affects 200 million people worldwide and also knowns as “swimmers itch” where the worms crawl into ur pores and cause itchy bumps