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Fun With Flatworms!. Alyssa Morazé, Natalie Moloney, and Ethan Yip. Fun With Flatworms!. Planaria spp. aggregation response to injured conspecifics. Alyssa Morazé, Natalie Moloney, and Ethan Yip. “Fun” Flatworm Facts. Free living aquatic worms Class Turbellaria Acoelomate - PowerPoint PPT Presentation
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Fun With Flatworms!
Alyssa Morazé, Natalie Moloney,
and Ethan Yip
Fun With Flatworms!
Alyssa Morazé, Natalie Moloney,
and Ethan Yip
Planaria spp. aggregation response to injured conspecifics
“Fun” Flatworm Facts
Free living aquatic worms Class Turbellaria
Acoelomate Two eye spots called ocelli
that are photoreceptors Negatively phototactic
Abundant tactile and chemoreceptor cells
BRIAN D. WISENDEN & MELISSA C. MILLARD
• Tested whether Planarians showed any response when chemical cues from injured conspecifics were introduced (in Dugesia dorotocephala)
• Crushed up a conspecific and placed in ‘Danger Zone’• Test worm immediately
turned 180 when in the ‘Danger Zone’• Did control test with
water and found significant differences
So… WHY?• Found other studies that showed natural
aggregation in flatworms• Thought back to schooling in fish lab and how
social grouping can be a predation response• Found no prior studies linking aggregation to
antipredator response in flatworms
• We hypothesized that we would see a difference in the tightness of aggregation in response to IC stimulus
Materials and Methods
1. Do they actually aggregate?
• 5 flatworms in a petri dish
• 5 minutes to Acclimate• Photograph taken• Image J software
measuring• 3 trials
Three tests to accomplish our goal:
2. Do individuals respond to injured conspecifics?
Single flatworm given 5 minutes to acclimate
Photos taken starting at 5 minute mark every 15 seconds
Single planarian crushed Added to edge of Petri dish Behaviour of flatworm noted for two
minutes at 15 second intervals 3 trials of Injured Conspecifics and 3
trials of Control of water also used as stimuli
Distance from planaria to edge of Petri dish calculated
*Attempting to recreate the results of the Wisenden and Millard Study
3. Is there group response to injured conspecific?
5 flatworms/Standard Petri dish 1 minute acclimation, photo every 15s for 1min Injured conspecific solution added Photo every 15s for 2mins Average Nearest Neighbour Analysis
0 1 2 30
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Trial Group
Aver
age
near
est n
eigh
bor d
istan
ce (c
m)
Results1. Do they actually aggregate?
Found no significant differences between trials Showed no tendency towards aggregation or dispersal
Figure 1: The mean ± SEM between each flatworm and their nearest neighbour in three different replicates (N=15).
2. Do individuals respond to injured conspecifics? Could not replicate the findings of Wisenden and Millard No significant difference between acclimation period and
stimulus No significant difference between treatment and control
1 2 30
1
2
3
4
5
6
7
Control Injured Conspecific
Trial Group
Aver
age
Dist
ance
from
Poi
nt o
f Stim
ulus
(cm
)
Figure 4: Side by side comparison of post stimulus response of the control (tank water as stimulus) and the treatment (injured conspecific solution)
3. Is there group response to injured conspecifics?
Table 2: Average group response (nearest neighbour values in cm) before and after introduction of tank water as stimulus
Pre-Stimulus Post-Stimulus ANN S.D. ANN S.D. p =Group 1 1.57 0.188 1.43 0.373 0.3469Group 2 1.00 0.373 1.33 0.281 1.349Group 3 x x 0.996 0.181 x
Table 3: Average group response (nearest neighbour values in cm) before and after introduction of ICS as stimulus.
Pre-Stimulus Post-Stimulus ANN S.D. ANN S.D. p =Group 1 1.23 0.407 1.36 0.405 0.582Group 2 1.34 0.420 1.28 0.323 0.791Group 3 0.946 0.170 1.12 0.344 0.233
No significant difference in ANN analysis before/after introduction of stimulusNo significant difference between control and treatment
Discussion ANN values around 1… threshold for
clumping/dispersal
Directly contradicted findings of Wisenden & Millard (2001)- Said organisms avoided areas where injured chemical cues
present
Directly contradicted findings of Reynierse et al. (1967)- Tested anitpredator response in Dugesia dorotocephala
This flatworm species doesn’t show antipredator aggregation response
Future Avenues• Red light – too intense?• Larger sample size?• Larger area• Single, well identified species of flatworm