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Post on 12-Dec-2014




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  • 1. Dragonflies Feeding on Amphipods; Size Does Matter Linda White, Kenny Danner, Shane Murnan, Craig Henson, and Lori Espieg Research Scientist: John White

2. Introducingour study subject

  • We will be studying theHylellaamphipod.

3. Introducingour prey

  • Dragonfly nymph

4. Step 1

  • We added 400 mL of non-chlorinated well water to fifteen individual sandwich sized 900 mL quart serving containers .

5. Step 2

  • We placed four four inch segments of ambulia plastic aquarium plants.

6. Step 3

  • All of the containers were left overnight to reach ambient temperature and oxygenate the water.

7. Step 4

  • Dragonfly larvae were separated into individual plastic beverage containers overnight to rest.Dragonfly larvae were not fed to ensure that each dragonfly had an appetite.

8. Step 5

  • We separated all of the amphipods into four categories; small, medium, large, and females with broods. The females with broods were placed in a separate container.

9. Step 6

  • We placed eight small, eight medium, and eight large amphipods into each container.

10. Step 7

  • After allowing the amphipods to rest in the containers, we placed one dragonfly larvae in each container.

11. Step 8

  • After allowing nature to take its course, we returned to examine our results.

12. 13. Step 9

  • The dragonfly larvae had a bigger appetite than expected.We found no amphipods.All of our test subjects had been consumed.

14. Step 10

  • We conducted our experiment a second time using eight of each size amphipod in each arena.We placed the females with broods in a separate container.

15. Step 11

  • Our dragonfly larvae were left in the arenas for twelve hours.After twelve hours the dragonfly larvae were separated from the amphipods.

16. Step 12

  • We placed the remaining amphipods and dragonfly larvae in a vial with ethanol solution killing juice to preserve them for measuring.

17. Step 13

  • We sorted the amphipods based on size remaining on Petri dishes for each arena.

18. Step 14

  • Using a microscope, we measured the head length of each of the remaining amphipods.
  • We measured the head width of each dragonfly larvae.

19. Step 15

  • All of our data was entered into a spreadsheet so we could draw conclusions based on our data.

20. Results

  • We determined that the dragonfly larvae preferred the medium size amphipods to the small or large amphipods.

21. 22. Conclusions

  • Through the analysis of our data, we determined that the dragonfly larvae prefer amphipods that are medium sized.
  • Reasons for this could be the energy used to catch the amphipod in relation to the energy gained by consuming the amphipod.

23. Ideas for Future Study

  • Comparing females with and without broods to males of the same size.
  • Comparing females with and without broods.
  • Increase the variation of dragonfly larvae size.

24. More Ideas for Future Study

  • Painting black dots on males to determine if it increases visibility or attractiveness.
  • Analyze energy content to determine if females with broods provide a higher energy return for dragonfly larvae.
  • Introduce other predators to determine which size amphipod they prefer.

25. Potential Predators

  • Toe Biters
  • Crawfish
  • Tadpoles
  • Fish

26. Disclaimer 27.

  • Questions?