Phylum Platyhelminthes

What does the name Platyhelminthes mean?

Flatworms

Where do flatworms live?

Marine habitats, freshwater habitats, moist terrestrial environments, and as parasites inside other organisms.

What are the 3 tissue layers in flat worms?

Ectoderm, mesoderm and endoderm

What type of digestive system do flatworms have?

A gastrovascular cavity

What are the functions of the gastrovascular cavity?

Digestion and circulation

How many openings does the flatworm digestive system have?

one opening which is the mouth and anus

What type of symmetry do flatworms have?

Bilateral symmetry

What is the rostral end

The head

The tail end

caudal

What does acoelomate mean?

lacks coelomic activity

what surrounds a flat worms gut

mesoderm

what is the function of mesoderm in flatworms?

mesoderm directly surrounds the gut

What is the function of the mesoderm in flatworms?

Movement through muscular action.

How do ciliated ectodermal cells help flatworms?

They aid in locomotion

Are Turbellarians parasitic or free-living?

free living

where do planarians live?

freshwater

What type of feeder is a planarian?

Carnivore

Where is the mouth located in planaria?

In the middle of the ventral side.

What structure protrudes from the mouth during feeding?

the pharynx

What do planarians eat?

Insect larvae, small crustaceans, and small living or dead animals.

How do planarians reproduce?

Both sexually and asexually.

Are planarians hermaphroditic?

Yes, they have both testes and ovaries.

How do planarians move?

Cilia and muscular contractions

What are the black spots on a planarian’s head?

Light-sensitive eyespots.

What are auricles?

Lateral projections that function as chemoreceptors.

Why are planarians difficult to see in ponds?

Their color camouflages them among rotting leaves.

What happens when egg yolk is placed near planaria?

They quickly sense and move toward it.

What does the carbon-fed planaria whole mount show?

The branched gastrovascular cavity.

Why is the gastrovascular cavity highly branched?

To circulate nutrients throughout the body.

What is obvious in the middle cross section of planaria?

The large muscular pharynx.

What surrounds the pharynx?

A space outside the body proper.

How is the gastrovascular cavity arranged anterior to the pharynx?

One median tube.

How is the gastrovascular cavity arranged posterior to the pharynx?

Two lateral tubes with no median tube.

Which tissue layer lines the gut?

Endoderm

Which tissue layer covers the outside of the body?

Ectoderm

What type of muscles run through the mesoderm?

Dorsal-to-ventral muscle bands.

What are Trematodes commonly called?

Flukes

Are Trematodes parasitic or free-living?

Parasitic.

Why are Trematode life cycles considered complex?

They involve multiple hosts and life stages.

What is Opisthorchis also called?

Clonorchis or liver fluke.

What structures are found at the anterior end of the liver fluke?

Mouth and sucker disc.

What is the purpose of the sucker discs?

Attachment to the host.

How many intestinal tubes does the liver fluke have?

Two simple tubes.

What is the dark-colored organ in the center of the liver fluke?

The uterus filled with eggs.

Where is the ovary located in the liver fluke?

behind the uterus

What structure is found at the posterior end of the ovary?

Seminal receptacle.

What is the branched pink organ in the posterior region?

testes

How do liver fluke eggs leave the human body?

feces

What organism first eats the eggs?

freshwater snails

What is the hatchling stage called?

Miracidium.

Which fish commonly become infected with liver flukes?

Minnows and carp.

How do humans become infected with liver flukes?

By eating raw or undercooked infected fish.

Where do adult liver flukes mature in humans?

liver

What are Cestodes commonly called?

Tapeworms

Do tapeworms have a digestive system?

no

How do tapeworms obtain nutrients?

By absorbing them through the body wall.

What is the scolex?

The head region of a tapeworm.

What structures are found on the scolex?

Hooks and four suckers.

What are proglottids?

Tapeworm body segments.

What do mature proglottids contain?

Testes, ovaries, uterus, and hundreds of eggs.

Why do tapeworms produce so many eggs?

Because few eggs survive to complete the life cycle.

How do mature proglottids leave the human body?

through feces.

What are the intermediate hosts for Taenia species?

Cattle and pigs.

What happens when intermediate hosts eat eggs or proglottids?

Larvae hatch and encyst in muscle tissue.

What is inside the bladderlike cyst?

One or more inverted scolecies.

How do humans become infected with Taenia?

By eating raw or undercooked infected meat.

What happens to the scolex after ingestion?

It turns outward and attaches to the intestinal wall.

Where do adult tapeworms live in humans?

In the intestine.