1. Emily, Azaria, Chris Period 5
Platyhelminthes
Emily, Azaria, Chris
Period 5

2. General Description Phylum- Platyhelminthes contains flatworms
Soft, unsegmented, & flat (no more than a few mm thick)
Tissues (tripoblastic) & internal organ systems
Simplest animals to have: 3 embryonic germ layers, bilateral symmetry, & cephalization
Do not have coeloms (body cavity)
Live in fresh or marine water
Most of their oxygen through diffusion

3. Symmetry No body cavity- aceolomates Bilateral symmetry
Gastrovascular cavity with one opening
Some breath through skin

4. Feeding
Parasites- enter body of other organisms, can absorb and consume what the host eats
80% are free living
Turbellaria- carnivores (tiny aquatic invertebrates)

5. Circulation Flatworms take in oxygen and release carbon dioxide
Flatworms don’t undergo cellular respiration
Flatworms undergo diffusion to obtain the oxygen they need, and release carbon dioxide they don’t
This is mostly the reason why they’re flat
Central nervous system: the complex of nerve tissues that controls the activities of the body.

6. Excretion
The digestive cavity has only one opening for both intake of food and the excretion of it
As a result the food cannot be processed continuously
Cilia help move foods to be digested and then excreted through their mouths
Pharynx: the membrane-lined cavity behind the nose and mouth, connecting them to the esophagus.
Flame cell: a specialized excretory cell- function like a kidney, removing waste materials.

7. Response They have ganglia
Have a complex structure for detecting and responding to external stimuli
Have eyespots that can detect changes in the amount of light in their environment
Have specialized cells that detect external stimuli

8. Movement
Free-living
Uses cilia and muscle cells

9. Reproduction Most are hermaphrodites
Reproduce sexually with internal fertilization
Parasitic
Commonly reproduce asexually by fission
Can reproduce sexually

10. Respiration
Gas exchange
Uses diffusion

11. Classes of Platyhelminthes
Trematoda
Turbellaria
Cestoda

12. Trematoda Parasites Infect animals and humans
Specialized body (Parasitic life)
Fasciola hepatica (Liver fluke)

13. Turbellaria Free living flatworms Most are aquatic
Some are terrestrial
Planaria

14. Cestoda Tape worms Intestinal parasites
Proglottid: segment containing complete reproductive system
Taenia solium (Pork tapeworm)

15. Works Cited https://www.shapeoflife.org/video/flatworms-first-hunter

16. The End