What are the stages of trematodes?
platyhelminthes • All digenetic trematodes have indirect life cycles. host & under suitable conditions miracidium hatches. Hatching is controlled by light temperature & salinity. Five larval stage are miracidium, sporocyst, rediae, cereariae & metacercariae.
Why are trematode life cycle complex?
Complex life cycles are a hallmark of parasitic trematodes. In several trematode taxa, however, the life cycle is truncated: fewer hosts are used than in a typical three-host cycle, with fewer transmission events. Eliminating one host from the life cycle can be achieved in at least three different ways.
Which life cycle stage of the trematode life cycle is infective to the vertebrate host?
Adult metacercariae
Adult metacercariae or mesocercariae, depending on the individual trematode’s life cycle, will then infect the vertebrate host or be rejected and excreted through the rejected host’s faeces or urine.
What is the structure of trematode?
Structurally, trematodes are flat and elongated worms whose outer surface (tegument) contains microvilli that both protect the worm and act as a nutrient absorptive surface. Adult worms possess anterior and ventral suckers, which are useful in maintaining attachment to host tissue.
Who is the final host in the trematode life cycle?
First intermediate host: The host (usually a mollusc) in which trematode larvae multiply asexually to produce cercariae. Metacercariae: The final larval stage in the life cycle of trematodes, which are usually encysted and quiescent in the second intermediate host.
Which parasite passes its life cycle through three hosts?
digenan trematodes
… is illustrated by the typical three-host life cycle of digenan trematodes, a type of parasitic flat worm which are often referred to as ‘flukes’ (Figure 1).
Which of the following trematode stages are present in every trematode life cycle?
There are three distinct larval stages involved in all digenetic trematode life cycles: the miracidium, sporocyst, and cercaria. Some taxa also produce rediae and/or encysted metacercariae. All of these life stages except for the miracidium can be found in first intermediate hosts.