Overview of Flatworms and Roundworms

Platyhelminthes

Phylum containing flatworms, including three classes.

Turbellarian

Class of free-living flatworms, e.g., Planaria.

Planaria

Example of Turbellarian, exhibits cephalization.

Cephalization

Development of a head region in organisms.

Bilateral symmetry

Body plan with symmetrical left and right sides.

Hermaphrodites

Organisms possessing both male and female reproductive organs.

Cross-fertilization

Sexual reproduction involving two different individuals.

Asexual reproduction

Reproduction without the involvement of gametes.

Mesoderm

Middle layer of cells in triploblastic organisms.

Trematoda

Class of parasitic flatworms, known as flukes.

Chinese Liver Fluke

Example of a Trematode that infects the liver.

Cestoda

Class of parasitic flatworms, known as tapeworms.

Scolex

Head of a tapeworm with hooks for attachment.

Nematoda

Phylum of roundworms, including hookworm and filaria.

Filaria

Worm causing elephantiasis, transmitted by mosquitoes.

Trichinosis

Disease caused by consuming undercooked infected meat.

Annelida

Phylum of segmented worms, including earthworms.

Oligochaeta

Class of Annelida, includes earthworms and leeches.

Symptoms of Tapeworms

Nausea, weakness, diarrhea, abdominal pain, fatigue.

Longest Tapeworm

Recorded length of 30 feet in humans.

Characteristics of Planaria

1. Free-living

2. Non-parasitic

3. Bilateral in shape

4. Exhibits cephalization: has a head

5. moves away from light ( crossed eye spots)

6. Has a brain

7. Has definite organs

8. Has a digestive system ( its mouth is its' anus)

9. They are hermaphrodites

10. They can reproduce sexually by cross-fertilization

11. They can reproduce asexually ( by cutting it in half)

Triploblastic

they have 3 layers of cells...the middle layer is known as the mesoderm