Platyhelminthes (Intro)

flat worms ---Class: Trematoda, Cestoda, Turbellaria

Class Turbellaria

aka Planarians; non-parasitic helminths, reside in fresh water

Class Trematoda

aka Flukes; Parasitic, monozoic (unsegmented body)

Class Cestoda

aka Tapeworms; parasitic, usually polyzoic (segmented body)

Schistosoma

long and narrow-bodied flukes

stomach flukes

thickly fleshed flukes

Fasciola

leaf-like flukes

tegument

most helminths that do not have an alimentary tract rely on ___ to absorb nutrients

Schistocomatidae

only family in Class Trematoda that are not hermaphrodites

Monogenea and Digenea

Two subclasses of Trematodes based on their life cycles

Subclass Monogenea

Subclass of Trematoda that needs only one host for reproduction, has a direct life cycle (no intermediate host), primarily external parasites of fish and other amphibious animals.

Subclass Digenea

subclass of Trematoda that needs more than one host for reproduction, found exclusively in vertebrates and are of considerable vet importance, eggs are shed usually in feces/urine of final host

molluscan (usually snail) IH

Where do the larval stages of Subclass Digenea develop

attachment

function of two muscular suckers on adult flukes

acetabulum

ventral sucker of adult flukes

anterior end

location of adult flukes’ oral suckers

cross and self

types of fertilization that may occur to Trematodes

seminal vesicle and cirrus

structures found inside the cirrus sac

vitelline glands

where does the yolk acquired by the ovum to form shells come from (female flukes)

ID the parts

mollusc

in most spp of Trematoda, the first intermediate host is a ____ in which further development of hatched larvae takes place

nematodes

one egg : one adult

flukes

one egg : hundreds of adults

parthenogenesis

flukes can perform ____ inside the mollusc host

miracidium

a pyriform (pear-shaped) larva develops inside the egg

light and temperature

stimuli that trigger the miracidium to release an enzyme that attacks the proteinaceous cement that holds the operculum in place

operculum

hinged lid that springs open where the miracidium emerges within a few minutes

~ 30 mins

how long does the entire process of penetration of miracidium into the soft tissues of a suitable snail host take?

metacercaria

infective stage of flukes for grazing animals

mastication (mechanical)

once metacercaria is ingested by grazing animals, how is the outer cyst wall removed

intestine

rupture of the inner cyst of metacercaria occurs in which organ?

marita

emergent juvenile fluke is often called what?

Egg → Miracidium → Sporocyst → Redia → Cercaria → Metacercaria → Marita → Adult

stages of the complete life cycle of flukes

Gymnocephalous

cercariae with long simple tail

Leptocercous

other name for gymnocephalous

Furcocercous

cercariae with a forked tail

Fasciola spp

flukes spp — Gymnocephalous

Schistosoma spp

Flukes spp with forked tail

Lephorcercous

cercariae with a dorsal, long, undulating fin fold

Opistorchis spp

spp of flukes that are Lephocercous

Gymnocephalous/Leptocercous

ID the cercariae

Furcocercous

ID the cercariae

Lephocercous

ID the cercariae

Microcercous

ID the cercariae

Cercariaeum

Cercariae with no tail

Trichocercous

ID the cercariae

Trichocercous

cercariae with spiny tail

Microcercous

Cercariae with small stumpy tail

Monostome

Classification of fluke with an oral sucker but no ventral sucker

amphistome

fluke with an oral sucker and an acetabulum at the posterior end

Cyclocoelum spp

example of monostome fluke

Zygocotyle spp

example of amphistome

Distome

has an oral sucker and acetabulum found at the anterior end

Alloglossidium spp

example of distome fluke

Cyclocoelum spp

Monostome spp

Zygocotyle spp

Amphistome spp

Alloglossidium spp

Distome spp

Cyathocotyle spp

holostome spp

Echinostoma spp

Echinostosome spp

Schistosoma spp

Schistosome spp

Holostome

a type of distome that has the body split into distinct anterior and posterior portions

Echinostome

has spines surrounding the oral sucker; head collars are present

Schistosome

has a strong oral sucker and an acetabulum near the anterior end