Phylum Phylum PlatyhelminthesPlatyhelminthes

Platyhelminthes:Platyhelminthes:

1. “Flat”worm2. One body

opening3. Very simple

Nervous & Muscular Systems

4. May be Parasitic or Free living

Planarian: (Class Planarian: (Class Turbellaria)Turbellaria)1. Free-living flatworm with

2. Bilateral Symmetry

3. Lives in freshwater

4. Found under leaves & rocks

5. Feeds on dead or slow moving organisms

6. Reproduction:

a. Sexually: Hermaphrodites = Male & Female Parts

b. Asexually: Fission = can regenerate body parts

7. Nervous & Sensory System

a. Brain-like Ganglion located in anterior region

b. Nerve cord to carry impulses

c. Eyespots: sense light & dark

d. Sensory pits line sides of head to aid in movement

e. Cilia line body & aid in movement

f. Flame cells remove excess water & nitrogenous wastes

7. Digestion: Food enters mouth & solid wastes exit mouth

a. Mouth: located in center of ventral side

b. Pharynx: tube-like struture which extends from mouth during feeding-acts like a

straw sucking up food & carrying it to the body

Freshwater flatworms have simple ganglia and nerve cords that run the length of the body. The excretory system consists of a network of tubules connected to flame cells that remove excess water and cell wastes.

Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism.

Flatworms use a pharynx to suck food

into the gastrovascular cavity. Digested food

diffuses from the cavity into other cells of the body. Eyespots

in somespecies detect light.

EyespotHead

Mouth Pharynx

Flame cell

Figure 27–3 Page Figure 27–3 Page The Anatomy of a FlatwormThe Anatomy of a Flatworm

1. Parasitic Flatworm

2. Lives in the Intestines of Vertebrates

3. Can grow up to 10 meters in length!

4. Reproduction: Hermaphrodites

Tapeworm (Class Cestoda)Tapeworm (Class Cestoda)

5. Flattened body is made up of individual segments called: Proglottid

a. Each proglottid is detachable

b. Each proglottid may contain up to 100,000 eggs

c. Fall off when full

d. Released with wastes

6. Head Region: Scolexa. Surrounded by hooks & suckers to

aid in attachment to intestine

b. Smallest section of worm

c. Proglottids grow out from scolex

7. Life cycle:

a. Eggs hatch in intestines of Intermediate Host (pig)

b. Young worms burrow into pig muscle

c. Secondary Host (man) eats undercooked/raw meat contaminated w/ worm larvae cysts

d. Larvae hatch & mature in intestines, must live in intestines since they don’t have them e. Attach to intestines and soak up digested food of host f. May enter bloodstream & infect other tissues w/ cysts

1. Parasitic Flatworm

2. Lives in Digestive System or Liver

3. Feeds on cells, blood, & body fluids

4. Blood flukes:

a. Eggs are released in water from wastes of infected host

b. Hatch into larvae

c. Larvae enter snail where they develop & reproduce

d. Enter water again & bore into skin of new host

Flukes(Class Trematoda)Flukes(Class Trematoda)

e. From blood, they bore into intestines

where they attach & feed on blood

5. Liver flukes:a. Lodge in liver ducts of host

b. Block liver ducts which can cause liver damage or failure

Quiz #2

Flatworms

IN

1. Planarians have ___ symmetry. a. bilateral b. radial c. assymetrical d.

symmetry

2. Flatworms reproduce sexually, they are hermaphrodites, what does this mean?

A. produce only sperm C. produce only eggsB. produce egg & sperm D. none

3. A tapeworms body is made of individual segments called __ A. segments B. flame cells C. scolex D. proglottids

4. The difference between planarians and tapeworms?a. planarians are parasites, tapeworms are freeliving

b. tapeworms are parasites, planarians are freeliving

c. both are parasites d. all the above

5. The function of ___ is to remove excess water & wasteA. pharynx B. flame cells C. fission D. cysts