Phylum Platyhelminthes
characteristics:
Platyhilmenthes are the flatworms, and are triploblastic acoelomates, which display bilateral symmetry. They are still very primitive, still not displaying a complete digestive system, but have an excretory system consisting of flame cells, which excrete waste through pores throughout the body. Flatworms have a primitive nerve ladder nervous system, and display exceptional regenerative capabilities, which can be used as a form of asexual reproduction. In addition to asexual reproduction, flatworms can also reproduce sexually. Flatworms are the first organisms to begin to display cephalization, where nerves are collected near the anterior region of the body, forming a primitive brain. Free-living flatworms have primitive eyespots, which can detect light, but not display images. They also have small auricles, which can pick up vibrations. There are three classes of Platyhimlenthes: Turbullaria (the free-living flatworms), Trematoda (the parasitic flukes), and Cestoidea (the tapeworms).
Lab:
results:
1. A human tapeworm can be as long as 60 feet! How is this possible when the human intestine is only 20 feet long?
The Tapeworm folds itself up so that it 'stacks' its proglottids so that it can fit in a small area in the human intestine.
2. What is the function of the hooks and suckers on the scolex?
The hooks are for attachment to the intestine wall, the suckers are for sucking nutrition from the digested food passing through.
3. In what ways is Chlonorchis similar to Planaria? In what ways are they different?
Both are flat worms with large gastrovascular cavities of similar shape (bilateral symmetry).Chlonorchis, being a parasitic flatworm, has a sucker for hooking on to the intestine of it's victim while Planaria, eing a free-living flatworm, doesn't need one.
4. What do each of the germ layers develop into?
Ectoderm- nerve ladder and skin
Endoderm- digestive system
Mesoderm- Muscles and reproductive organs
5. In what way are flatworms more advanced than Cnidarians?
Flatworms are more advanced than Cnidarians because they have all three germ layers (troploblastic), flame cell excretory system, nerve center and nerve net instead of no nerve center and nerve ladder of Cnidaria, incredible regeneration system, Auricles for sensing vibration and eyespots for sensing light.
Flatworms are Triploblastic (have all three ger cells
6. Name the characteristics of Platyhelminthes:
(Above in 'Characteristics')
7. Explain or define these terms:
a) Hermaphroditic: an animal with both male and female reproductive parts.
b) Ladder-type nervous system: a system of nerves belonging to phylum Cnidaria that consists of two ventral nerve cords that connect to the nerve center at the 'head' or anterior area of the worm. nerve cords connect perpendicular to the two main cords, attaching them together like steps on a ladder.
c) Flame Cells: Pore-like openings all over a flatworm's body where it excretes it waste. this is unlike the Cnidarian's way of doing it, as their mouths are also their anus'.
d) Regeneration: When a flatworm is damaged, it uses a type of healing that starts from scratch by using stem cells to re-grow that part of the body that was damaged, if split in half, the flatworm(s) will grow back the other half of their bodies and form 2 full worms.
8. Compare the structure of taena, and endoparasyte, with a Planarian, and active, free-living predator in a table:
The Tapeworm folds itself up so that it 'stacks' its proglottids so that it can fit in a small area in the human intestine.
2. What is the function of the hooks and suckers on the scolex?
The hooks are for attachment to the intestine wall, the suckers are for sucking nutrition from the digested food passing through.
3. In what ways is Chlonorchis similar to Planaria? In what ways are they different?
Both are flat worms with large gastrovascular cavities of similar shape (bilateral symmetry).Chlonorchis, being a parasitic flatworm, has a sucker for hooking on to the intestine of it's victim while Planaria, eing a free-living flatworm, doesn't need one.
4. What do each of the germ layers develop into?
Ectoderm- nerve ladder and skin
Endoderm- digestive system
Mesoderm- Muscles and reproductive organs
5. In what way are flatworms more advanced than Cnidarians?
Flatworms are more advanced than Cnidarians because they have all three germ layers (troploblastic), flame cell excretory system, nerve center and nerve net instead of no nerve center and nerve ladder of Cnidaria, incredible regeneration system, Auricles for sensing vibration and eyespots for sensing light.
Flatworms are Triploblastic (have all three ger cells
6. Name the characteristics of Platyhelminthes:
(Above in 'Characteristics')
7. Explain or define these terms:
a) Hermaphroditic: an animal with both male and female reproductive parts.
b) Ladder-type nervous system: a system of nerves belonging to phylum Cnidaria that consists of two ventral nerve cords that connect to the nerve center at the 'head' or anterior area of the worm. nerve cords connect perpendicular to the two main cords, attaching them together like steps on a ladder.
c) Flame Cells: Pore-like openings all over a flatworm's body where it excretes it waste. this is unlike the Cnidarian's way of doing it, as their mouths are also their anus'.
d) Regeneration: When a flatworm is damaged, it uses a type of healing that starts from scratch by using stem cells to re-grow that part of the body that was damaged, if split in half, the flatworm(s) will grow back the other half of their bodies and form 2 full worms.
8. Compare the structure of taena, and endoparasyte, with a Planarian, and active, free-living predator in a table:
Value |
Endoparasite: Taena |
Free-Living: Planaria |
Body Structure |
-Head/scolex at the front/anterior region that houses suckers and hooks for attachment and feeding -Proglottids that are full of reproductive organs produces great numbers of eggs |
y-Anterior region: Nerve center, eyespots, auricles -Nerve Ladder -Ventral Pharinx -Both sexual organs -Large gastrovascular cavity |
Eyes |
no eyes (not needed) |
eyespots (sense light,not full-functioning eyes) |
Nervous System |
No nerve system |
Nerve Laddwer |
Digestive System |
Eats digested food from the host through sucker, excretes waste by flame cells |
Eats by hooking on to food with pharynx, excretes waste by flame cells |
Reproductive system |
Proglottids behind the scolex hold both reproductive organs (hemaphroditic) and create and fertalize hundreds of eggs. |
-Sexual: have both male and female reproductive organs (hemaphroditic) -Asexual: by the powers of regeneration, if split in half, two Planarians will be created. |
Planarian Lab
1. list 3 characteristics of flatworms:
-flat
-long
-flame cell excretory system
2. what type of symmetry does this worm have
bilateral
3. where do planarians live:
freshwater and saltwater ponds
4. draw your planarian: (below)
5. measure your planarian:
11mm
6. observe the planarian for 5 minutes, record what you see in the table provided. (below)
7. What 'hand' is your planarian: 3 tests: right, 2 tests: left. therefore the planarian is right handed.
8. make an experiment about how the planarian reacts to light and dark:
purpose: to observe a planarian's reaction to light and darkness
hypothesis: if the planarian is exposed to light, then it will be more afraid and will be less motile because it is easier to see and it knows that it is more visible to predators.
materials: microscope, paper towel, planarian
procedure:1. expose planarian to the light of the microscope for 30 seconds, turn off the light and record movement.
2. cover the planarian's 'tank' with paper towel for 30 seconds, uncover and record movement.
Observations: after being exposed to light, the planarian moved at a normal-fast pace and stretched out full when moving along the bottom of the 'tank'. after being exposed to darkness, the planarian moved at a slow rate and did not stretch itself out fully when moving along the bottom of the 'tank.'
9. how does the planarian eat the food: a white tube comes out from the ventral surface of the planarian, and it attaches to the food. the white 'mouth' is called the pharynx.
10. define hermaphrodite: has both reproductive organs
define regeneration: the use of stem cells to completely repair an injury
if cut in half, and the planarian becomes 2 planarians via regeneration, what kind of reproduction is that: asexual
make a cut on your planarian, observe: (we cut below the head diagonally towards the middle of the planarianright of the head) the head moves but the section cut does not, it is dragged along with the body.
make a prediction, how long do you predict it will take for your planarian to completely regenerate: 3-5 days
Results: the planarian completely fused itself with no visual scarring of any kind this happened anywhere between 1-3 days/
-flat
-long
-flame cell excretory system
2. what type of symmetry does this worm have
bilateral
3. where do planarians live:
freshwater and saltwater ponds
4. draw your planarian: (below)
5. measure your planarian:
11mm
6. observe the planarian for 5 minutes, record what you see in the table provided. (below)
7. What 'hand' is your planarian: 3 tests: right, 2 tests: left. therefore the planarian is right handed.
8. make an experiment about how the planarian reacts to light and dark:
purpose: to observe a planarian's reaction to light and darkness
hypothesis: if the planarian is exposed to light, then it will be more afraid and will be less motile because it is easier to see and it knows that it is more visible to predators.
materials: microscope, paper towel, planarian
procedure:1. expose planarian to the light of the microscope for 30 seconds, turn off the light and record movement.
2. cover the planarian's 'tank' with paper towel for 30 seconds, uncover and record movement.
Observations: after being exposed to light, the planarian moved at a normal-fast pace and stretched out full when moving along the bottom of the 'tank'. after being exposed to darkness, the planarian moved at a slow rate and did not stretch itself out fully when moving along the bottom of the 'tank.'
9. how does the planarian eat the food: a white tube comes out from the ventral surface of the planarian, and it attaches to the food. the white 'mouth' is called the pharynx.
10. define hermaphrodite: has both reproductive organs
define regeneration: the use of stem cells to completely repair an injury
if cut in half, and the planarian becomes 2 planarians via regeneration, what kind of reproduction is that: asexual
make a cut on your planarian, observe: (we cut below the head diagonally towards the middle of the planarianright of the head) the head moves but the section cut does not, it is dragged along with the body.
make a prediction, how long do you predict it will take for your planarian to completely regenerate: 3-5 days
Results: the planarian completely fused itself with no visual scarring of any kind this happened anywhere between 1-3 days/
#4
#6:
Movement |
'creeps along the ground forwards, usually towards the wall of the bowl. 'glides' along the wall with a current of some kind. |
Location |
crawls along the bottom until it gets to the wall, glides along the wall, crawls top the bottom, across the bottom, and up another side. |
Reaction to current |
squishes up in a ball, once it feels safe, stretches out again. |