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Bio 11 SS Worm Exam Review

Worms Exam Review


  1. The body of a segmented worm is divided into segments, separated by what structure?
  2. Which worm has a proglottid and what does it do?
  3. What is the tough outer covering of a nematode called?
  4. What tissue is a coelom lined with?
  5. What is cephalization?
  6. In which worm phylum/phyla do the members have a developed circulatory system?
  7. In what way is the digestive system of the roundworm considered more advanced than that of the flatworm? (2 reasons)
  8. Why is cephalization associated with motility? (2 reasons)
  9. Which characteristics do flatworms share with hydra?
  1. What is a structure or characteristics are shared by all the worm phyla?
  1. In which of the worm phyla do blood vessels appear?
  1. Which of worms have a complete one-way digestive tract
  1. A fluid-filled, mesoderm-lined body cavity is known as a
  1. How would you list worm phyla from least to most advanced?
  2. Which type of worms (common names) are found in phylum Annelida?
  3. How do Annellia worms breath or respire?
  4. What is an organ designed to grind food in the Annelid digestive system?
  5. If an organism is a hermaphrodite what organs would it have?i
  6. What is the dorsal saddle like structure called in segmented worms called and what is it’s function?
  7. What are some common names for both parasitic and free living Nematods?
  8. What is a concentration of nervous tissue that functions as a simple brain is called
  9. What is the function of the scolex?
  10. Looking at a cladogram , what is an evolutionary development first seen in Nematodes?
  11. Which worm has a closed circulatory system?
  12. What is th most highly developed organ system in a tapeworms ?
  13. Why are adult tapeworms have reduced or absent digestive systems?
  14. To avoid being infected by the trichinella worm what should you do?
  15. Proper sewage treatment could control which types of worms (common names like blood worms, flukes or latin names?
  16. What is the order in which food pass down the digestive system of an earthworm?


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

Bio 11 Worm Test Check

So here are some questions to test how good your study card is..

Last minute guide for worms


  • What do hydras have in common with flatworms?
  • What is a structure that all worms share for eating?
  • Which worm has closed blood vessels and why is this important?
  • Which worms have a digestive system that goes one way from mouth to anus?
  • Which worms do not have a one way digestive system?
  • What is a fluid filled mesoderm lined body cavity called?
  • How are worms ranked from simple to most complex?
  • How are annelida worms different from other types of worms.
  • What is the big deal about body segmentation?
  • How do worms “breath”?
  • How do earth worms grind up their food and where?
  • It is a “dorsal saddle like swelling”, what is it called and where is it found?
  • What are examples of nematode worms, using common names.
  • What is a concentration of nervous tissue called?
  • Which worm has a “scolex” and what is it used for?
  • It is found only in nematode worms and it is not found in flat worms nor annelida worms. What is it? Clue..It is some times referred to as an evolutionary development.
  • What is the most developed organ system in a tape worm?
  • Why does a tapeworm never have to worry about digesting food?
  • With proper sewage system, which worms can be controlled?
  • What is the order of organs in an earthworms digestive system? Why is this unique?
  • How are segments in an earthworm segmented separated?
  • What is the name and function of a reproductive structure in tapeworms?
  • What is the function of cuticle?
  • What is a coelom full of?
  • What is the use for a hydrosketon?
  • What is cephalization?
  • What are the structures and function of a closed circulatory system and which worm has one?
  • How are the three types of worms ( flat, round and segmented) different when it comes to digesting food? Which would be the most advanced and why?
  • If an organism forms a brain or has cephalization, how could this be linked to mobility?
posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Notes,Worms and have No Comments

Bio 11 Worm Study Guide

Bio 11 Worm Lab Sheet                          Name____________________________


Your mission is to dissect a worm.

Using your “map” or diagram of worm anatomy, you will prepare a study guide which you can use for the lab quiz.


The lab quiz will be pictures of actual dissections or pictures of live worms.


You will also need to be able to discuss 5 systems of the worm.


  1. Digestive system
  2. Circulatory System
  3. Excretory System
  4. Nervous System
  5. Reproductive System


A system is a group of organs, composed of tissues and cells. You will need to identify specific organs and their function.


You should also answer the following questions (from “Biology Corner”)


  1. What is the name of the pumping organs of an earthworm?
  2. Trace the parts of the digestive tract through which food passes.
  3. Which parts of the earthworm serve as its brain?  How are these parts connected to the rest of the body?
  4. Which of the parts of the worm’s body that you saw are included in the excretory system?
  5. How can you find out whether an earthworm eats soil?
  6. Among the earthworm’s structural adaptations are its setae. How do you think the earthworm’s setae make it well adapted to its habitat?
  7. How is the earthworm’s digestive system adapted for extracting relatively small amounts of food from large amounts of ingested soil?
  8. Your dissection of the earthworm did not go beyond segment 32.What will you observe if you dissect the remainder of the worm to its posterior end?
  9. On a separate piece of paper, ( or your study guide) draw and label the parts of the earthworm you observed, and color code the systems. Use green for the reproductive system, yellow for the digestive system, blue for the excretory system, and red for the nervous system.
  10. During mating, two earthworms exchange sperm. Fertilization is external, and cocoons are produced from which the young eventually emerge. Refer again to steps 5 and 11, where you located the earthworm’s reproductive organs. Use a reference to identify the role of each organ in the reproductive process of the earthworm. On a separate paper, summarize your findings.
posted by Marc Bernard Carmichael in Biology Eleven Notes,Worms and have No Comments

Bio 11 (2016-17) Worms 2 May 24th

Bio 11 (2016-17) Worms 2                 Date May 24, 2017



Last lessons Objective



1.   Worms (that are flat)

2.   Drawing and life cycle

Today’s Objectives  

1.   Round worms (Nematoda)

2.   Segmented (Annelida)



Number One

Key Points for round worms

1.   Pseudocoelomate

2.   Full digestive system

  1. Parasitic.
  2. Unsegmented.
  3. Complex cuticle without cilia.
  4. Intermal fertilization.
  5. 1cm to 8m in length.
  6. No circulatory system.
  7. Alimentary tract present.


Notes on Nematoda

10.                 See gap notes and check green duotang


Filarian worms in the eye



worms in face



Guinea Worm disease




Student youtube about nematode



Nematoda Classification




Number Two




What is new?

1 coelomate

2 Closed circulatory system with hemoglobin

3 hermaphroditic with internal fertilization

4 waste management via nephridia

5 segmentation

6 ectoparasite

7 hydroskeleton and dorsal pore

8 Advancement of muscle control

9 More complex cephalization


What is the big deal about earthworms?



Annelida Classification



Porifera to Annelida



Diversity of things



Using leeches for medicine



Science of leeches




Sample Annelida: “the earth worm”


10 facts about earthworms




Number Three

Prep for earthworm lab

Earthworm Anatomy



virtual dissection



Text book Reference Chapter Twelve
You tube Reference  

Comparing nematode to annelida




Practice quiz and worksheets :Annelida



Practice quiz and worksheet: Nematoda



Comparison youtube





Take Home Message It is ok…we found the worm!
posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Lesson Outline,Worms and have No Comments

Bio 11 Annelida Gap Notes

Biology 11

Name: ________________ __________________ Date: ________________ Block: __________


Phylum Annelida (Latin: anellus = “little ring”)

The “Segmented” worms

Pages 323-327


  1. Background:


  • 2 Major Classes: (Really there are 4 classes)
  • Though there are truly 4 classes of Annelids we will only look at 2 of the classes, and 2 of the sublclasses found within the Phylum Annelida


    1. Class ________________________: (Means “Many Bristles”)
    2. Class ________________________:
      • Subclass ________________________________: The Earthworms (Means “Few Bristles”)
      • Subclass ________________________________: The Leeches


  • ~15000 known species
  • The Annelids live in many diverse environments including freshwater, marine and terrestrial
  • Some Annelids can form symbiotic relationships including parasitic Annelids and mutualistic Annelids


DID YOU KNOW!!!: The giant Australian Earthworm can grow to be up to 3 meters in length


  1. Body Plan/Structure: (Based on the Earthworm Body Plan)


  • The Annelids demonstrate a ____________________________ symmetrical body plan
  • They have the three true germ layers:
    • ____________________________
    • ____________________________
    • ____________________________
  • Just underneath the _____________________ lays a _____________________ which helps stop the Annelids from ______________________________ in terrestrial habitats
  • Annelids have a true _________________________ with a _______________ and ______________ connected by ______________________________
  • The mouth is controlled by a muscular _________________________and is connected to the ___________________________ by an ____________________________
  • After the ___________________________ is a sac-like part of the intestines called a _________________
  • Just after the ____________________ is the _________________ which aids in digestion
  • Annelids have large ___________________ on the ___________________ side of the their anterior end which acts as a primitive brain
  • The _______________________are connected to a ________________________ which runs down the ________________________ side of the body
  • Annelids are the first organisms we will look at that possess a true __________________ that is lined with ___________________________
  • The Annelids have both _____________________ and ____________________ muscles
  • Annelids are the first group of organisms that we will look at which have a ________________________________________________. Their circulatory system is made up of two _______________________________ which run along the length of the body on the ________________and __________________ sides. There are also a series of “______________” in the _____________________ end which pump the blood through the circulatory system.       These “hearts” are called the ________________________.
  • Annelids are ____________________________ and contain both male and female reproductive organs.
  • These organs are found just anterior to a special structure called a ______________________ which is a swollen segment near the _______________ end of their body.
  • They are also the first organisms we will study that demonstrate true ___________________________:
    • Each segment of the Annelid worms contains similar structures to the next segment
    • Each segment is called a _______________________ and is separated from the next by a ______________________(plural = ________________). This is formed from of a double layer of __________________________
    • Annelid worms contain little bristles on their exterior called _________________ which aid in locomotion. The setae can be found in four pairs per segment and are made out of ___________________
    • Each segment of an Annelid contains a pair of _____________________ which are used for excretion
    • Each segment of Annelids have a _________________muscle which lays just beneath the ______________________



III. Feeding:


  • The Annelids are very diverse in the way that they feed.
  • Some are __________________________ and live off of theirs host’s blood such as the leeches (Hirudinea)
  • Others are __________________________ and hunt their prey such as the marine Polychaetes
  • Other Polychaetes such as the Christmas tree worms, the fan worms and other tube worms are ______________________________________
  • We will focus on the Earthworm (Oligochaeta) feeding:
    • Most Earthworms are called ____________________________ which means that they eat decomposing organic matter
    • As Earthworms travel through the dirt they suck the dirt into their mouth using their muscular _________________________
    • The Earthworm sends the dirt through the ________________________ and into the _________________ by muscle contractions
    • The dirt is stored in the ______________ until the worm is ready for digestion
    • Using muscle contractions the dirt moves into the ___________________________ which acts much like a _______________________________
    • The ___________________ mechanically digests the dirt and organic material by mixing it. The sand in the dirt aids to grind the organic material into small pieces
    • The organic material and dirt continues along the ___________________ by muscle contractions
    • As it travels through the intestines the organic material is absorbed into the ______________ in the _______________ and ________________ blood vessels
    • The remaining inorganic dirt travels through the ___________________ to the __________________


  1. Respiration:


  • Again, we will focus on the Earthworm for respiration
  • The circulatory system of Earthworms contains _______________________ which contains ___________________________.
  • ______________________ is taken into the Earthworm directly through the ______________________ by the process of _____________________
  • The oxygen enters the blood and is held by the _________________________ in the __________________ which carries the oxygen to the body cells of the Earthworm
  • _____________________________ exits the circulatory system directly through the ectoderm and into the Earthworm’s surroundings by the process of __________________


  1. Internal Transport:


  • All Annelids have _______________ circulatory systems which contain ______________ which in turn contains ___________________________
  • The _________________________ in the blood gives the blood its red colour
  • The haemoglobin in the blood transports __________________ throughout the Annelid
  • The circulatory system of Annelids is made up of the ______________________________ which are a series of muscular “______________” in their __________________ end, and a _______________ of blood vessels which run along the _______________ and ___________________sides of the worm
  • The _______________________________ pump the blood through the ________________ blood vessel and collect blood from the _____________blood vessel
  • The blood vessels branch into ________________________________that are found along the _____________________ and the ______________________
  • These capillary beds are sites of ________________________, both for __________________________ at the ectoderm and ______________/___________ exchange at intestine
  • The blood transports ____________ , ____________________ and ________________ throughout the Annelid body


  1. Excretion:


  • One form of excretion in Earthworms is directly out of the _______________
  • Undigested inorganic and organic food particles are expelled out of the anus
  • These mishmashes of inorganic and organic material are called _____________________
  • Another form of excretion in Earthworms uses structures found in every segment called ______________________:
    • There are two _________________ in each segment and they have two openings:       the first opening opens into the _________________ cavity of one segement, then the ___________________ pass through the __________________ into the next ______________________ segment where they open into the surroundings of the Earthworm
    • Wastes are excreted by the body cells, circulatory system and intestines into the ______________________ cavity
    • The _____________________ collect the waste material from the ______________________ cavity of one segment and transport it out of the earthworm in the next _______________________ segment.



VII. Response:


  • Earthworms are able to sense and respond to the following stimuli:
    • ____________________
    • ____________________
    • ____________________
  • Most of the Earthworm’s sensory organs are found in the ______________________ end
  • Once they have sensed stimuli the ________________________ interpret the information and send the information along the ventral ________________________ to control the response and movement of the segments
  • As the nerve cords enter each segment they bulge to form individual ______________________ in each segment
  • These _______________________ allow each individual segment to respond quickly


VIII. Movement:


  • Earthworms move by a process known as _______________________:
    • Earthworms are unique in that they are made of individual segments that act together in unison
    • Earthworms have both _____________________________ muscles which run down the entire body as well as ___________________ muscles in each segment
    • Starting at the _____________________ end the ____________________ muscles contract while the ___________________________ muscles relax. This causes the anterior end to become ___________________ and elongate.
    • After “stretching” the __________________________ muscles contract while the ____________________muscles relax.       This causes the anterior end to become fat again
    • As the body stretches the __________________ extend from the sides of the body to anchor into the soil
    • As the _________________________ muscles contract the Earthworm drags itself forward
    • If this process of contracting and relaxing of the longitudinal and circular muscles is done in sequence along the entire body it allows for easier motion and is called peristalsis


DID YOU KNOW!!!: Human beings also perform peristalsis, however, we use the process to

swallow our food. Try eating or drinking upside down one time and see what happens!!!




  1. Reproduction:


  • Asexual reproduction:
    • Annelid worms can undergo the process of _________________ to produce two genetically identical worms
    • Annelids can also _______________________ after they have been cut


DID YOU KNOW!!!: Earthworms can be cut up to 1/13 their size and still regenerate!!!


  • Sexual Reproduction:
    • Earthworms are _________________________ (though other Annelids have distinct sexes)
    • When conditions are right two earthworms will line up ____________ to __________ so that their _________________________ and their _______________ line up (male to female)
    • The ___________________________ of each worm then produce a slime tube that surrounds both worms
    • ___________________ is transferred from each partner to the other
    • Once copulation has occurred the worms wriggle out of the slime tube releasing the _____________ and _________________
    • The sperm fertilize the eggs within the worm “__________________”
    • The eggs mature directly into the adult Earthworms which emerge from the “cocoon”


  1. Ecological Roles:


  • Annelids play incredible ecological roles
  • Earthworms are very important to agriculture. As they burrow through the soil they help to aerate it allowing the roots of plants to gain much needed space and oxygen. The castings they leave behind also help to fertilize the soil
  • Some countries around the world use medicinal leeches. In Medieval times leeches were used to suck people’s blood in hopes of balancing their “Humours”. In modern medicine the chemical that leeches secrete during feeding called hirudin is used to prevent blood coagulation in certain operations such as plastic surgery or to stimulate circulation in reattachment surgeries.
posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Notes,Worms and have No Comments

Bio 11 Nematoda Gap Notes

Biology 11

Name: ___________ _______________ Date: _________________ Block: _____________



Phylum Nematoda (Greek: nema = “thread”)

The “Roundworms”

Pages 314-317


  1. Background:


  • 2 Major Classes:
    1. _______________________________
    2. _______________________________
  • ~ 80000 species known


DID YOU KNOW!!!: Nematodes are the most abundant multicellular lifeforms on earth!!!


  • The Nematodes have evolved to live in every habitat on the planet from marine to fresh water, the polar regions to the tropics and from the highest elevations to the lowest.
  • Nematodes can be ____________________________ or _______________________


  1. Body Plan/Structure:


  • Nematodes demonstrate a __________________________ symmetrical body plan
  • They have a _________________and ____________________________ body
  • They lack a ______________________
  • They have three germ layers:
    1. ______________________
    2. ______________________
    3. ______________________
  • Nematodes are the fist phylum we will look at that has a _____________________________________________ with a _________________ and an _____________ connected by __________________________
  • The mouth is connected to the intestines by a muscular _______________________
  • Nematodes are ___________________________________ which means that they have an internal body cavity but this cavity is not lined with __________________________
  • They do have muscles but only ___________________________ ones
  • They have ____________________ in their __________________ end which is connected to two __________________________ that run down the length of the body on the ________________ and ____________________ sides
  • Nematodes secrete a thick _______________________ that surrounds the body and protects them from their surroundings


DID YOU KNOW!!!: Nematodes are born with the same number of cells that they will have for

their entire life. This means that as Nematodes grow they do not get new cells; instead their cells just get larger!!!


III. Feeding:


  • The free-living Nematodes usually eat bacteria, fungi, protozoans along with other decomposing material
  • Parasitic Nematodes live off of their host organism
  • Food is ingested through the mouth by muscular contractions of the _________________
  • The food is digested in the ________________________
  • Undigested food is passed out of the _______________


  1. Respiration:


  • Respiration occurs by simple _____________________ where oxygen is taken up by the body cells from the surroundings and carbon dioxide is released from the body cells into the surroundings


  1. Internal Transport:


  • The Nematodes lack a true _______________________________; However, nutrients diffuse from the intestines into the __________________________ where they circulate throughout the body


  1. Excretion:


  • Wastes and undigested nutrients are released out of the _____________ of Nematodes
  • They also have _____________________________________ on either side of their body which release wastes into the surroundings from the pseudocoelome





VII. Response:


  • Nematodes can have the ability to sense and respond to three stimuli:
    1. Sense and respond to ________________
    2. Sense and respond to ______________________
    3. Sense and respond to _________________


VIII. Movement:


  • Since Nematodes lack __________________________ muscles and only have _________________________ muscles they can only slash around from side to side


  1. Reproduction:


  • Sexual reproduction (free-living):
    • Most Nematodes are either ________________ or _______________ (though some are hermaphroditic)
    • When a female and a much smaller male Nematode meet the male will wrap his ________________ around the female
    • One or more ______________________ will move out of his anus and will be inserted into the females _____________________ and sperm will be transferred
    • The fertilized eggs are released from the female into the surroundings to mature


  1. Ecological Roles:

Parasitic Nematodes:


Like the Platyhelminthes there are many forms of Nematodes that are parasitic. They

Are mostly parasitic on vertebrates and can cause serious illness. They also have very complicated lifecycles:


Ex. Trichenella spiralis (causes Trichinosis)


  • These Nematodes only need one host to mature but can be passed from host to host
  • The adult Nematodes live in the intestine of their host (pig/rat/human)
  • When they undergo sexual reproduction the larva burrow into the muscles of their host and create a capsule around themselves called an encyst
  • After maturing the larvae travel back to the intestines to begin the lifecycle again


DID YOU KNOW!!!: Most Humans get Trichinosis from eating undercooked pork which

contains the larvae filled encysts!!!



The Nematode known as Caenorhabditis elegans (C. elegans) was the first multicellular organism ever to have its entire genome mapped. Researchers found that C. elegans have

~ 100 million base pairs that code for ~20000 genes. Research in this area began way back in 1974 and it was completed in 2002. Since then the scientists involved in the research have won multiple Nobel Prizes in medicine and physiology. Also, since C. elegans has been extensively researched it has been used as a model organism to demonstrate cell differentiation and development, cell death, neuronal development, genetic processes, meiosis and many other processes.

posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Lesson Outline,Worms and have No Comments

Bio 11 Platyhelminthes Gap Notes (1)

Biology 11

Name: __________________ __________________ Date: ______________ Block: __________


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

The “Flatworms”

Pages 311-317


  1. Background:



  • ~ 25000 known species
  • Some flatworms are free-living whereas other flatworms are completely parasitic and require a host to survive


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 tale region
  • 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. 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. 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. Ecological Roles:


  1. B) 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):

Ex. Taenia saginata (The Beef Tapeworm)

  • The tapeworm has an anterior end called a scolex with complicated hooks for attaching to the intestines of its host.
  • The tapeworm does not have a mouth or digestive system. Instead they bath in the pre-digested fluids of their host and absorb nutrients directly into their body cells
  • Since they live in such a harsh environment as the intestines they have a modified ectoderm called a tegument which protects them from the host’s digestive enzymes and immune responses
  • The tapeworm is hermaphroditic and has an incredibly adapted body which is a reproducing powerhouse!!!
  • The body of the tapeworm is segmented into proglottids, each containing their own group of the necessary sexual organs.
  • 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 fecal matter.
  • Lifecycle:
    • After the fertilized eggs have been released in the fecal matter of the human host the feces can be used as fertilizer, especially in underdeveloped countries with poor sewage systems etc.
    • The eggs are ingested by the intermediate host, a cow
    • The eggs mature into larva in the stomach of the cow which then 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):

Ex. Schistosoma mansoni (The Liver Fluke that causes Schistosomiasis)

  • The fluke worm has an anterior end with an oral sucker
  • Fluke worms also have a tegument like the Tapeworms to protect them from their host’s immune system and digestive juices
  • Flukes are most often hermaphroditic 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 larvae 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 each other 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.


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