Flatworms & Roundworms

Question 1

What are the 3 groups of worms?

Answer 1

Platyhelminthes
Annelida
Nematoda

Question 2

Which 2 groups are protostomes split into?

Answer 2

Lophotrochozoa

Ecdysozoa

Question 3

What is helminthology?

Answer 3

Study of flukes, tapeworms & roundworms

Question 4

What is the difference between parasites & parasitoids?

Answer 4

Parasite = not fatal to host

Parasitoid = fatal

Question 5

What are the 2 types of parasite depending on where they live?

Answer 5

Endoparasite = inside host

Exoparasite = on host

Question 6

In terms of reproduction, what must parasites do?

Answer 6

Reproduce within host

Get fertilised eggs/embryos out of host

Question 7

In terms of their habitat, what must parasites do?

Answer 7

Recognise & contact new host

Get into new host

Find right location in host & stay there

Question 8

In terms of survival, what must parasites do?

Answer 8

Withstand anaerobic conditions

Avoid host digestive & immune systems

Avoid killing host

Question 9

How can some flukes alter snail behaviour?

How can they alter the snails’ appearance?

Answer 9

Cause them to seek light in the open so more likely to be eaten by bird

Cause eyestalks to resemble caterpillars

Question 10

How can flukes alter the physiology of Potamopyrgus antipodarum?

Which hypothesis is this an example of?

Answer 10

Strong correlation between sexual reproduction & extent of nematode infection

Heavy load = sexual
Light load = asexual

Red Queen hypothesis

Question 11

What is the common name fro Platyhelminthes?

Answer 11

Flatworms

Question 12

Describe the features of Platyhelminthes.

Answer 12

> Simplest of the lophotrochozoans
Triploblastic
Aceolomates
25,000 species

Question 13

Why are Platyhelminthes flat?

Answer 13

= cells near surface

No organs for transporting O2
–> Only simple organs for excreting waste

Question 14

Which flatworm class is probably most similar to ancestral flatworm forms?

Answer 14

Turbellaria

= free living flatworms

Question 15

How do motile flatworms move?

Answer 15

Beating broad bands of cilia

Question 16

Describe the flatworm digestive system.

What do they feed on?

Answer 16

= mouth opening into blind sac
- highly branched sac increases SA
(no anus)

Living or dead animal tissue
- release digestive juices then suck digested food through pharynx

Question 17

What is special about Schmidtea?

Answer 17

They’re regenerative

Question 18

What is special about the Digenean life cycle?

Answer 18

5 stages:
miracidium, sporocyst, redia, cercaria, metacercaria

2+ intermediary hosts 
- 1st = mollusc
Specificity towards molluscan host 
Asexual reproduction in intermediary hosts 
Sexual in vertebrate definitive host

Question 19

What is the main characteristic of:

>Turbellaria (class)?

Answer 19

All non-parasitic forms

Question 20

What is the main characteristic of:
>Trematoda (class)?

> Digenea (subclass)?

> Aspidogastrea (subclass)?

Answer 20

> Parasitic flukes

> Adults often in digestive tract of vertebrates

> Marine & freshwater fishes & turtles

Question 21

What is the main characteristic of:
> Cercomeromorpha (class)?

> Monogenea (class)?

> Cestoda (class)?

Answer 21

> Typically attach w/ discs of hooks

> 1 host e.g. fish scales or frog bladder

> Tapeworms in organs of vertebrates

Question 22

Which class are Monogenea in?

Answer 22

Cercomeromorpha

Question 23

Describe what the Frog bladder fluke (Gorgoderina attenuate) does.

This is an example of which subclass?

Answer 23

Larva attach to tadpoles that hatch from eggs

• -> as tadpole metamorphoses into a frog, parasite migrates to host’s bladder
• -> parasite takes 3yrs to become adult

Monogenea

Question 24

Which class are Cestoda in?

Answer 24

Cercomeromorpha

Question 25

What are cestodes?

Answer 25

Parasitic worms aka tapeworms

Question 26

Tapeworms are an example of which subclass?

Answer 26

Cestoda

Question 27

Describe the features of tapeworms

Answer 27

> Non-cilliated teguments
Teguments have no cell membranes - syncytial (multi-nucleated)
No digestive tract - acquires nutrients via highly folded outer surface
Scolex binds to intestine & buds proglottids
Proglottids = hermaphrodites & produce eggs

Question 28

Describe the beef/pork tapeworm life cycle

Answer 28

1. Egg eaten by cow/pig
2. Egg hatches into onchosphere –> bores through intestine –> transported in blood to muscle –> forms cysticercus
3. In undercooked meat… cysticercus evaginates –> scolex attaches to gut wall
4. Proglottids containing eggs defecated
5. REPEAT

Question 29

Which superphylum are Nematoda in?

This means they have what feature?

Answer 29

Ecdysozoa

Animals grow by ecdysis = shedding their exoskeleton

Question 30

What is the exoskeleton called in ecdysozoans with wormlike bodies?

Answer 30

Cuticle

= thick, flexible exoskeleton

Question 31

Describe a nematode’s coelom

Answer 31

Pseudocoelomates

= coelom between endoderm & mesoderm

Question 32

What are nematodes commonly known as?

Answer 32

Roundworms

Question 33

What are the features of nematodes?

Answer 33

> cylindrical w/ tapered ends
thick cuticle
longitudinal muscle only - strong sphincters around gut & reproductive openings
high turgor pressure
complete gut
separate sexes
exchange O2 & nutrients w/ environment via cuticle & intestine

Question 34

What are the Nematode examples?

Answer 34

Wuchereria bancrofti
= inhibits lymphatic glands
–> elephantiasis

Onchocercal filariasis
= acquired from black flies & causes nodules under skin &/or blindness

Question 35

Which class are Dignea in?

Answer 35

Trematoda

Question 36

Which class are Aspidogastrea in?

Answer 36

Trematoda