1. Bellwork: Fri. May 5, 2017
Write the following classification in your bellwork:
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Turbellaria
Order: Tricladida
Family: Planariidae
Genus: Dugesia
Species: tigrina

2. Remember yesterday’s bellwork
“Red Yucca”
Kingdom: Plantae
Phylum: (clade) Angiosperms
Class: (clade): Monocots
Order: Asparagales
Family: Asparagaceae
Subfamily: Agavoideae
Genus: Hesperaloe
Species: parviflora

4. Laboratory Investigation
Observing Planaria
Laboratory Investigation

6. What are Planaria? Freshwater flatworms: (phylum: Platyhelminthes)
Live in freshwater under leaves and stones
Avoid light (“negative phototaxis”)
Free living – not parasites
Carnivores – eat decaying meat, insects and larvae (egg yolks or liver in the lab)
1-20 mm in size
Long lived
Use sexual or asexual reproduction
This picture has been released it into the public domain.

7. Overview of Brown Planaria Dugesia tigrina

8. Planaria are complex organisms
Gastrovascular
System

9. Nervous
System

10. Reproductive
System

11. Excretory/Osmoregulatory
System

12. Why study Planaria
Planaria have an amazing ability to regenerate parts of themselves
Planaria regeneration is a great model for demonstrating stem cell function and complexity of tissue regeneration
They can grow easily in the lab
1/279th

13. Neoblast = Planaria Stem Cell
20-30% of all the cells in a planaria are Neoblasts.
Neoblasts divide by mitosis and can make more of themselves. They are the only dividing cells in planaria.
When a planaria is wounded, neoblasts migrate to the site and begin dividing
Neoblasts can become ANY cell the planaria needs—nerve cells, flame cells, reproductive cells…
Ann. Rev. Cell. Dev. Biol. 20: , 2004

15. Neoblasts and Stem Cells are Totipotent
“Totipotent” Stem Cell
Blood Nerve Skin
They can become any cell type in the body
In Humans: Totipotent cells are limited to
early embryonic division
In Planaria: Neoblasts are always present

16. Care and Feeding of Planaria
The water is very important! Fresh water from a pond, stream or lake is best; spring water is adequate
Keep cultures in a cool, dark place
Feed planaria at least once a week
Change the water twice a week, especially after feeding
After cutting them, the cultures should not be fed

17. Laboratory Investigation
Each team will receive 1 planaria:

18. Plenty of Planaria

19. Planaria Regeneration, Days 1 - 14
Slide courtesy of Dr. Sánchez Alvarado and Dr. Kyle Gurley

20. Slide courtesy of Dr. Sánchez Alvarado and Dr. Kyle Gurley

21. Slide courtesy of Dr. Sánchez Alvarado and Dr. Kyle Gurley

22. Bellwork: old final review
You may use a word once or not at all: write each statement
Independent variable Hypothesis Theory Quantitative Qualitative
1. Testable, scientific explanation for observations:__________
2. Well-tested explanation supported by many observations_________
3. Variable that is deliberately changed in an experiment: ______ _________
Variable that changes because of the independent variable is the dependent variable
4. Data not involving numbers, but descriptions:______________
hypothesis
theory
Independent
variable
qualitative