Helminths

Question 1

What are the two groups of Helminths?

Answer 1

Platyhelminths

Nematoda

Question 2

What are the 4 sub-groups of Platyhelminths

Answer 2

Trematoda
Cestoda
Mongenea
Turbellaria

Question 3

What are the characteristics of Turbellaria?

Answer 3

• Small size
• Hemaphroditic
• Simple life cycles

Question 4

What is a parasitic example of Turbellaria?

Answer 4

Rhabdocoela

Question 5

What are the characteristics of Rhabdocoela

Answer 5

• Simple blind gut
• Infect echinodermata
• Feed on host intestinal tissue and eat host ingest
• feed on host gut ciliate symbionts

Question 6

What are some adaptations of Rhabdocoela

Answer 6

• Haemoglobin around cerebrospinal-pleural ganglion and gonads ro facilitate oxygen diffusion in hypoxic conditions

Question 7

What are the charecteristics of monogeneans?

Answer 7

• ectoparasitic
• Have a tegumental structure
• tegumental surface has microvilli

Question 8

The shape of monogeneans divide them into two groups, what are they?

Answer 8

• monopisthocotylea (single simple sucker)

- Polypisthocotylea

Question 9

What characteristics do trematodes have?

Answer 9

• Endoparasitic flukes with complex tegument and suckers

Question 10

What are the two sub-classes of trematodes?

Answer 10

• Digenea

- Aspidogastrea

Question 11

What are the characteristics of Digeneans?

Answer 11

• Compex life cycle (2/3 hosts)

- Normally molluscan 1st host

Question 12

What is the life cycle of digeneans?

Answer 12

1. Adult produces eggs which produce miracidium
2. Miricidium enters first host (molluscan)
3. First host produces cercariae
4. Cercarie exit first host and enter second host
5. Second host produces metacercariae
6. Metacercariae leave 2nd host and move into definitive host

Question 13

What are the two infection methods used by digeneans?

Answer 13

1. Internal (Ingested cystophores - cercariae produce tubes which penetrate host gut and bud off metacaricae in body cavities of host)
2. External (most common - free swimming cercariae locate host and use piercing stylet to inject proto-metacercaria stages into the intermediate host)

Question 14

What are the effects of digeneans on hosts?

Answer 14

• blockage of blood vessels/gut and other organs
• tolerable in wild, but in aquaculture where there is already stress, cause be fatal
• toothed whales infected with nastrema in their sinuses suffer damage to 8th (auditory) cranial nerve which have been linked t mass stranding

Question 15

What effects can digeneans have on host behaviour?

Answer 15

• infected periwinkles showed more migration to top of rocks in intertidal areas
• more likely to be eaten (and hence transmitted) by herring gulls

Question 16

What is crassicauda boopis and what does it do?

Answer 16

• Nematode
• Fin Whale Worm
• Head of worm found in blood vessel in the liver, middle in the kidney and tail end in the reproductive/excretory system
• can be 8 meters long
  (LEMPEREUR ET AL 2017)

Question 17

What are the 2 parasitic classes of acanthocephala

Answer 17

• Palaeacanthocephla

- Eoacanthocephla

Question 18

What can palaeacanthocephla do to amphipods?

Answer 18

Contorl them so their anti-predator behaviour is disrupted - get eaten by predators - passing on nematode