Purpose
To compare the structure and function of various Nematode body plans.
Materials
Microscope
Necator, Ancylostoma and Trichina slides
Dissecting equipment
Ascaris worm
Blank paper and pencil
Necator, Ancylostoma and Trichina slides
Dissecting equipment
Ascaris worm
Blank paper and pencil
Method
Part 1: The Dissection
1. Draw the dissected Ascaris round worm and label as many structures as possible
2. Locate the muscle fibres along the inside of the body wall
Part 2: The other worms
1. Hookworm - Draw a diagram of Necator (the human hookworm) and a diagram of Ancylostoma (dog hookworm)
2. Draw a diagroam of Trichina encrusted muscle tissue
1. Draw the dissected Ascaris round worm and label as many structures as possible
2. Locate the muscle fibres along the inside of the body wall
Part 2: The other worms
1. Hookworm - Draw a diagram of Necator (the human hookworm) and a diagram of Ancylostoma (dog hookworm)
2. Draw a diagroam of Trichina encrusted muscle tissue
Dissection
Results
Analysis
1. Q: In Ascaris, which direction do the muscles run; horizontally or vertically?
A: Vertically
2. Q: What forms the lateral line in Ascaris?
A: The main nervous cord
3. Q: Is there any evidence of sensory organs in Ascaris?
A: No
4. Q: In what ways is Ascaris adapted to a parasitic existance?
A: It has no sensory organs that appear in free-living nematodes, as it does not need to find its food. It only has a digestive system and reproductive organs, which is all it needs
5. Q: Describe the life cycle of Ascaris from egg to adult and back to egg
A: Eggs leave the human body in their feces. These feces land on the ground, leaving residue on fruits and vegetables. The eggs grow into baby worms, which then re-enter the body when someone eats the fruit without cleaning it. The larva go down into the small intestine, where it absorbs nutrients from food we digest and grows into an adult. Once fully grown, the worms begin to release eggs and sperm, and the fertilized eggs once again leave the worm in our feces.
6. Q: In what ways are hookworms similar to the Acaris
A: Both of the worms are parasitic, with no sensory organs, only posessing digestive and reproductive organs. They both live in the small intestine of humans, absorbing nutrients to sustain themselves that would be normally used for ourselves.
7. Q: How does Necator enter the body? How does it get inside the host's intestine?
A: When walking barefoot, the worm attatches to your feet and secretes fluid that causes your feet to itch. When scratched, tiny cuts open up in your feet, where the worms enter into your bloodstream. They then travel through the heart to the lungs and enter the respiratory system. They irritate your throat, causing you to cough them up. They then enter the digestive system when you swallow, and then travel to the small intestine where they latch onto the stomach lining and begin to grow.
8. Q: For the Trichina worm, how does it compare to Necator and Ascaris?
A: It has the same lack of sensory organs that appear in Necator and Ascaris. However, it lives in the muscle tissue, and is caught by eating undercooked pork.
9. Q: How can Trichonosis be prevented?
A: By fully cooking all pork that is eaten.
10. Q: What germ layer is the roundworms' pseudocoelum located between?
A: It is located between the mesoderm and the endoderm.
11. Q: What organs and organ systems are located in the nematodes body cavity between the two mesoderm layers?
A: The digestive organs (gastrovascular cavity) and the reproductive organs are housed in between the two mesoderm layers.
12. Q: In what ways are the parasitic members of Nematoda different from their free-living relatives?
A: The parasitic worms have no sensory organs, while the free-living worms have auricles (ears) and eye spots. Parasitic worms rely on people and animals to get and digest food for nutrients, while free-living worms eat and digest food on their own.
13. Q: What are the advantages and disadvantages of being a parasite?
A: Advantages - They don`t have to find your own food. They simply absorb nutrients that would normally go into their hosts` body. Once they are in place, they stay there for the rest of their lives and don`t have to look for food.
Disadvantages - If the victim is malnourished, the worm won`t get proper nutrients and will die. Without sensory organs, if the worm doesn`t make it into the body of a host, it will die of starvation. Once detected, the worms can be easily killed with antibiotics or surgeries.
14.
A: Vertically
2. Q: What forms the lateral line in Ascaris?
A: The main nervous cord
3. Q: Is there any evidence of sensory organs in Ascaris?
A: No
4. Q: In what ways is Ascaris adapted to a parasitic existance?
A: It has no sensory organs that appear in free-living nematodes, as it does not need to find its food. It only has a digestive system and reproductive organs, which is all it needs
5. Q: Describe the life cycle of Ascaris from egg to adult and back to egg
A: Eggs leave the human body in their feces. These feces land on the ground, leaving residue on fruits and vegetables. The eggs grow into baby worms, which then re-enter the body when someone eats the fruit without cleaning it. The larva go down into the small intestine, where it absorbs nutrients from food we digest and grows into an adult. Once fully grown, the worms begin to release eggs and sperm, and the fertilized eggs once again leave the worm in our feces.
6. Q: In what ways are hookworms similar to the Acaris
A: Both of the worms are parasitic, with no sensory organs, only posessing digestive and reproductive organs. They both live in the small intestine of humans, absorbing nutrients to sustain themselves that would be normally used for ourselves.
7. Q: How does Necator enter the body? How does it get inside the host's intestine?
A: When walking barefoot, the worm attatches to your feet and secretes fluid that causes your feet to itch. When scratched, tiny cuts open up in your feet, where the worms enter into your bloodstream. They then travel through the heart to the lungs and enter the respiratory system. They irritate your throat, causing you to cough them up. They then enter the digestive system when you swallow, and then travel to the small intestine where they latch onto the stomach lining and begin to grow.
8. Q: For the Trichina worm, how does it compare to Necator and Ascaris?
A: It has the same lack of sensory organs that appear in Necator and Ascaris. However, it lives in the muscle tissue, and is caught by eating undercooked pork.
9. Q: How can Trichonosis be prevented?
A: By fully cooking all pork that is eaten.
10. Q: What germ layer is the roundworms' pseudocoelum located between?
A: It is located between the mesoderm and the endoderm.
11. Q: What organs and organ systems are located in the nematodes body cavity between the two mesoderm layers?
A: The digestive organs (gastrovascular cavity) and the reproductive organs are housed in between the two mesoderm layers.
12. Q: In what ways are the parasitic members of Nematoda different from their free-living relatives?
A: The parasitic worms have no sensory organs, while the free-living worms have auricles (ears) and eye spots. Parasitic worms rely on people and animals to get and digest food for nutrients, while free-living worms eat and digest food on their own.
13. Q: What are the advantages and disadvantages of being a parasite?
A: Advantages - They don`t have to find your own food. They simply absorb nutrients that would normally go into their hosts` body. Once they are in place, they stay there for the rest of their lives and don`t have to look for food.
Disadvantages - If the victim is malnourished, the worm won`t get proper nutrients and will die. Without sensory organs, if the worm doesn`t make it into the body of a host, it will die of starvation. Once detected, the worms can be easily killed with antibiotics or surgeries.
14.
Taena
Clonorchis
Ascaris
Necator
Trichina
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Entering body
Through cuts in toes when host scratches
Egg consumed by snail, enters skin of fish as larva
On unwashed fruit/veggies
Enters through feet
Enters through mouth when consuming undercooked pork
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Where it lives
Attatches to wall of small intestine
All over in primary host, in liver of secondary host
Small intestine
Small intestine
Lives all over body in specific muscle tissues
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Host/Effects
Humans. Causes malnourishment
Snail=primary, animal=secondary
Humans, malnourishment
Humans, malnourisment
Humans and animals. It forms very painful cysts in muscles
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Prevention
Wearing shoes when walking in feces
Antibiotics, get rid of snails around animals
Wash fruit before eating
Don`t go barefoot
Make sure all pork is fully cooked before consumption
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