Phylum Platyhelminthes

Question 1

What is a morphologically different in platyhelminthes than in nematoda and acanthocephala?

Answer 1

• they’re flat worms.

Question 2

What are some features of Platyhelminthes?

Answer 2

• dorso-ventrally flattened and without cavity
• incomplete digestive tract or absent
• suckers and hooks
• hermaphrodites

Question 3

What are some features of trematodas?

Answer 3

• flukes
• ventral and oral suckers
• operculated eggs
• need at least one IH
• majority are endoparasites (in intestines, bile ducts and lungs) but some are ectoparasitic.

Question 4

What are some features of cestoda’s?

Answer 4

• tapeworms
• can be meters long
• small intestine
• IH

Question 5

What are some features of subclass digenea?

Answer 5

• endoparasites
• ventral sucker is used for attachment.
• incomplete digestive tract but no anus
• mouth is surrounded by oral sucker
• hermaphroditic
• males = testes and females = ovaries.
  IH = molluscs.

Question 6

What is the life cycle of subclass digenea?

Answer 6

adult -> miracidium -> sporocyst -> redia -> cercariae -> metacercaria -> adult

Question 7

Define the life stages of digenea.

Answer 7

• Adult
• Operculated eggs (lid)
• Miracidium (ciliated) - invade IH and multiply asexually
• sporocyst (in IH)
• radia (in IH) - motile and cause damage to IH
• cercaria - motile with tail develop inside rediae then settle on grass
• metacarariae - encyst form cercaria. can survive up to one year in the environment

Question 8

What are some features of fasciola hepatica?

Answer 8

• leaf like
• oral sucker around mouth
• caeca are branched and extended
• the testes are branched and extended posteriorly
• ovaries are in the middle
• vitelline glands
• eggs are yellow and operculated
• adults are in bile ducts of cattle, sheep, horses dogs and people
• juveniles migrate through the liver
  IH = snails
• miracidium develops in 8 days

Question 9

What is the infection pathway of the metacercaria?

Answer 9

• excyst in small intestine –> move to peritoneal cavity –> penetrate and burrow in liver –> bile ducts = adults

Question 10

What are some features of paramphistomes?

Answer 10

• stomach flukes
• cattle and sheep
• adults stages = rumen and reticulum
• immature = duodenum and abomasum
• attach to mucosa with posterior
• operculated

Question 11

What are some features of Dircocoelium?

Answer 11

• lancet fluke (small liver fluke)
• ruminants, horses, dogs and pigs
• in bile ducts and galll bladder
  IH = terrestrial snails and ants
• two suckers (anterior and ventral)
• miracidium with two germ balls