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Platyhelminthes Gap Notes


Biology 11


Name: _________________________ Date: __________ Block: _____



Platyhelminthes Anatomy

eg: Class Turbellaria, Family Planaria


Biology 11

Ms. L. Jamieson

Name: _________________________ Date: __________ Block: _____


Phylum Platyhelminthes: Flatworms

(Greek: platy = “flat”, helminth = “worm”)

Pages 311-317


  1. Background:


DID YOU KNOW!!!: The longest tapeworm ever to be extracted from a human was 37 feet long and was pulled out of a woman’s mouth!!! In whales they can grow up to 120 feet in length!!!


  1. A) Free-Living Platyhelminthes:

(Class Turbellaria)


  1. Body Plan/Structure:
  • Flatworms demonstrate a _______________________ symmetrical body plan
  • They are ____________________ flattened and lack a __________________
  • They have a highly branched _______________________________________. It is considered a ______________ gut because there is only one opening to it which serves the function of both the ______________ and ______________
  • They have three germ layers:
    1. ______________________: Outside
    2. ______________________: Inside
    3. ______________________: Middle layer of tissue between the ectoderm and the endoderm
  • Though Flatworms have three germ layers they are _______________________ and have no body cavity
  • Flatworms do have ___________________ and primitive __________________ that are used for __________________ and ___________________
  • Flatworms are also the most primitive organisms to show ___________________
  • The head region of Flatworms contains a concentration of __________________ called ___________________ (singular=_____________________) that resembles a primitive brain.
  • They have two __________________ that run from the __________________ in the head region along the ___________________ side of the worm to the tail.
  • In the head region of Flatworms are two ______________________________
  • They also have lobes on the side of their head called _____________________


III. Feeding:

  • The free-living forms of Flatworms are ______________and ______________
  • Flatworms have a ___________________ which is connected to the __________________ through a long       muscular ________________________
  • Small invertebrates or the remains of dead animals are taken into the mouth/anus by the muscular ____________________
  • The food is then digested in the highly branched ________________________
  • The nutrients moves from the gut into the body cells by __________________


  1. Respiration:
  • Respiration occurs by ___________________
  • ______________is taken up directly by the ________________ from the water or the gut
  • ______________________ is released directly from the _________________ into the water or the gut


  1. Internal Transport:
  • __________________ and ___________________ in the gut are simply absorbed into the body cells by the process of _____________________






  1. Excretion:
  • Most undigested food is released directly out of the _____________________
  • Other waste materials diffuse from the body cells into the _________________ and exit out of the ____________________
  • Other undigested food is released out of tiny ____________________ that open to the water


VII. Response:

  • Flatworms are able to sense and respond to at least three forms of stimuli:
    1. Sense and respond to __________________: The __________________ can detect light and allow the Flatworms to respond to it
    2. Sense and respond to ____________________: ____________ on the side of their head regions can sense ___________________ in the water and allow the Flatworms to respond (like “smelling”)
    3. Sense and respond to ________________: The ____________________ on either side of the head region can sense _______________ and allow the Flatworms to respond
  • The _____________________ in the head region relay messages from the sensory organs down the _______________________ to the rest of the body. The _______________________ can control _______________________ in the body which allow the Flatworms to ______________ or ________________.


DID YOU KOW!!!: Even though Flatworms only have primitive brains they are capable of



VIII. Reproduction:

  • Asexual Reproduction:
    • Flatworms can asexually reproduce through a process called ____________.       The ________________ and ________________ ends hold a surface and the midsection constricts. This results in two new flatworms, one from the _________________ end of the original flatworm and the other from the ____________________ end of the original flatworm.
    • Flatworms can also ________________________ parts they have lost.




DID YOU KNOW!!!: If you cut a small piece off the tip of a flatworm’s head region and left the wound open it will regenerate a new head in front of the old one. You can repeat the process to create a flatworm with many heads. If we were Greek we could call it a Polycephaloturbellarian!!!


  • Sexual Reproduction:
    • Flatworms are _________________________
    • After two flatworms have copulated they release sacs of fertilized __________ and attach them to a surface


DID YOU KNOW!!!: In the animal world it is much easier to be male because you generally

don’t have to take care of your offspring. Because of this some hermaphroditic flatworms demonstrate a sexual behaviour called “Penis Fencing” in which two flatworms will attack each other with their penises. The first one that can jab the other will release their sperm and thus take on the role of a male while the flatworm that has been jabbed will have their eggs fertilized and take on the role of the female!!!


  1. Movement:
  • The flatworms move across a surface using _________ on their _____________ surface
  • They can also move by contracting _______________ and _________________ muscles that lay just below the __________________. These muscles are controlled by the ___________________.


DID YOU KNOW!!!: Some flatworms are so muscular they can swim through the water!!!


  1. Ecological Roles:


  1. ____________________
  2. ____________________
  3. ____________________






Biology 11

Mr. Kalkman

Name: ______________________ Date: __________ Block: _____


Parasitic Platyhelminthes

(Classes Trematoda, Cestoda and Monogenea)


Parasitic Platyhelminthes are quite a bit different than their free-living relatives. Many of these adaptations are related to the fact that they live within host organisms. Most of the final host organisms that parasitic Platyhelminthes use are vertebrates, including HUMANS!!! However, they have intricate lifecycles with intermediate host organisms.


Here is a list of adaptations that make the fluke and the tape worms different than the free-living flatworms.


Class Cestoda (Tapeworms):

  1. The Beef Tapeworm
  • The tapeworm has a _______________ at its anterior end, with complicated hooks for attaching to the intestines of its host.
  • The tapeworm does not have a _______________ or _______________. They are bathed in the pre-digested fluids of their host, and absorb nutrients directly into their cells
  • Since they live in such a harsh environment as the intestines they have a modified ectoderm called a _______________ which protects them from the host’s _______________ and _______________
  • The tapeworm is _______________ and has a body adapted for reproducing.
  • The body of the tapeworm is segmented into _______________, each containing both male and female _______________.
  • As the eggs in the proglottids are fertilized they are released into the human host’s intestines and eventually end up in the host’s _______________.


  • Lifecycle:
    • After the fertilized eggs have been released in the fecal matter of the human host the feces can be used as fertilizer etc.
    • The eggs are ingested by the intermediate host, a cow
    • The eggs mature into larva which burrow into the muscles of the cow
    • The beef is eaten by more humans and the larva mature into tapeworms in the intestine of the human host to start the lifecycle again.





Class Trematoda (Flukes):

  1. Schistosoma


  • The fluke worm has an an _______________ on its anterior end for attaching to the host
  • Fluke worms also have a _______________ to protect them from their host’s _______________ and _______________
  • Flukes are most often _______________ but in the case of Schistosoma there is a male and a female form
  • Other than these adaptations flukes show many of the same characteristics as the free-living turbellarians


  • Lifecycle:
    • The adult fluke worm lives in the blood vessels near the intestine of a human host.
    • When it is ready to lay its eggs it pushes its way into one of the tiny blood vessels of the intestine and lays thousands of eggs
    • The sheer number of eggs causes the blood vessels to burst releasing the eggs into the intestine
    • The eggs are carried out of the human host in their fecal matter
    • In many underdeveloped countries there are no proper sewage system and the fecal matter is used as fertilizer
    • The eggs get into the water systems and mature into ciliated larva
    • The larva swim until they find a snail intermediate host. If they do not find this snail they will die
    • The larva burrow into the tissue of the snail, feed on its tissues and asexually reproduce
    • The new larvae exit the snail and become free-swimming
    • The new free-swimming larvae burrow into the skin of humans who are swimming near them
    • A male larva and female larva will find eachother and move through the human circulatory system until they reach the human liver where they mature and feed on red blood cells
    • The pair of mature trematodes migrate to the intestines where they undergo sexual reproduction
    • The female releases the eggs into the small blood vessels of the intestines to start the cycle again.




Biology 11

  1. Jamieson

Name: _________________________ Date: __________ Block: _____



Human Tapeworm Lifecycle:

Phylum Platyhelminthes, Class Cestoda, Taenia saginata





































Biology 11

Ms, Jamieson

Name: ____________________ Date: ___________ Block: _____



Liver Fluke Lifecycle

Phylum Platyhelminthes, Class Trematoda, Schistosoma mansoni




posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Notes and have No Comments

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