BIOL113 L26

Flatworms

Acoelomates with gastrovascular cavities, triploblastic, and range in size from nearly microscopic to over 20 m long.

Number of flatworm species

About 20,000 species living in marine, freshwater, and damp terrestrial habitats.

Parasitic flatworms

Flukes and tapeworms.

Flatworm digestive system

Gastrovascular cavity with only one opening.

Turbellaria

Class of flatworms that are nearly all free-living and mostly marine.

Planarian movement

Using cilia on the ventral epidermis and by gliding along a film of mucus they secrete.

Parasite features

Structural and behavioral adaptations, specialized yet simplified, complex life cycles, intermediate hosts, and larval reproduction.

Intermediate host

An animal in which development occurs but adulthood is not reached.

Definitive host

Animal harboring the adult or sexually mature stage of the parasite.

Adhesive organs in trematodes and cestodes

Used for attachment inside and outside the host's body.

Sense organs in endoparasites

Reduced to adapt to a parasitic lifestyle.

Nutrition modification in trematodes and cestodes

Modifications for direct absorption and storage areas.

Larval stages in parasite life cycle

Allow the parasite to find different hosts.

Suckers in trematodes and cestodes

Used for attachment to the host.

Trematodes' tough covering

Protects these parasites.

Trematodes' reproductive capacity

Increased, including asexual reproduction.

Schistosoma infection impact

Infects 200 million people, causing body pains, anemia, and dysentery.

Schistosoma adult worms location

Within the blood vessels of the colon and urinary bladder.

Paragonomiasis prevalence

In the Far East, Central America, and Africa.

Paragonomiasis transmission

Through the consumption of raw freshwater crabs and crayfish containing Paragonimus larvae.

Paragonimus eggs in fresh water

Hatch as ciliated miracidia, penetrating specific snails.

Lung fluke larvae infection

Metacercaria penetrate the human small intestine wall and migrate to the lungs.

Paragonomiasis symptoms

Lung abscesses, chronic cough, rusty colored sputum, and aberrant worms in tissues.

Paragonomiasis prevention

By cooking crab meat and sewage treatment.

Clonorchis sinensis prevalence

In China.

Liver flukes acquisition

By eating infected freshwater fish.

Liver fluke eggs in stool

Hatch as ciliated swimming miracidia in fresh water.

Liver fluke larvae maturation

Climbing up the biliary tree to mature in the intrahepatic biliary radicles.

Monogeneans

Mostly external parasites of fishes.

Monogenean infection start

Ciliated, free-living larva called Onchmiracidium.

Monogeneans on fish

Occur on the skin or gills.

Polystoma integerrimum

Bladder parasite of frogs living in the bladder of the common frog.

Polystoma integerrimum larvae attachment

To the internal gills of tadpoles.

Tapeworms habitat

Mostly in vertebrates, including humans.

Tapeworm anchoring

Suckers and hooks on the head or scolex anchor in the host's digestive tract.

Tapeworm proglottids

Mature proglottids with eggs leave with the host's feces.

Tapeworm eggs development

Into larvae in intermediary hosts like pigs or cattle.

Hydatid tapeworm larvae acquisition

By eating undercooked meat contaminated with cysts.

Hydatid tapeworm larvae development

Into mature adults within the human body.

Hydatid tapeworm scientific name

Echinococcus granulosus.

Hydatid tapeworm transmission

Through undercooked meat contaminated with cysts.

Platyhelminthes classes

Four classes - Turbellaria, Monogenea, Trematoda, and Cestodea.

Trematodes characteristics

Usually leaf-shaped.

Platyhelminthes size range

From microscopic to 100 ft long.

Platyhelminthes covering

Covered by a cytoplasmic tegument.

Platyhelminthes body cavity

Absent.

Platyhelminthes digestive system

Absent or rudimentary.

Platyhelminthes excretory system

Contains ciliated cells extending into excretory tubules.

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