Transcript Food Preference in Helix

Conditioning Towards Food
Preference in Helix aspersa
By: Emily Carter, Kate O’Brien &
Kimberley Wallace
Chemoreception
• Principle modality for location
• Amino Acids, Lactic acid, glucose metabolism
intermediates.
• Accurately discriminate food sources:
– Also need olfactory cues and feeding related stimuli
Food Preferences
• May have innate preferences:
– Quantity and quality
– Physiological condition
• Determined by two characteristics:
– Attractiveness and Edibility
• Important for protection of crops and
important plant populations.
Food Attraction Conditioning
• Influenced by: learning experiences and changes to
neural processes.
• Change in feeding experience.
• Teyke 1995:
• After a single feeding episode- preference
• No feeding period- no preference
• Just exposed to scent- no preference
Hypotheses
Helix aspersa will show a preference for the
conditioned food item.
• Apple condition = preference for apples
• Lettuce condition = preference for lettuce
• Control condition = no preference
Materials and Methods
• 6 Snails (Helix aspersa) in 3 separate tanks
-6 cups of soil in each tank and corresponding food type
Experiment
• Snail placed into middle Plexiglas enclosure
with apples and lettuce at opposite ends
• 20 minute testing period
• Distance, speed and preference of the snail
was recorded
Lettuce
Apples
• 2 trails conducted  each trial lasted 1 week
• Food was removed 1 day before trials to
ensure snails were hungry enough to eat
when placed in testing chamber
Results
• Results did not agree with original hypotheses
- Only Lettuce group had results that agreed with original
hypothesis
• No relationship among results that suggested
that snails can be conditioned towards a
particular food type.
Conditioned to Lettuce
8
7
7
6
Number of Snails
5
4
3
3
2
2
1
0
Apple
Lettuce
Food Regiime Type
Neither
Conditioned to Apple
7
6
6
Number of snails
5
4
3
3
3
2
1
0
Apple
Lettuce
Feed Regime Type
Neither
Conditioned to Apples and Lettuce
7
6
6
5
Number of Snails
5
4
3
2
1
1
0
Apple
Lettuce
Food Regime Type
Neither
Speed of Snails (cm/min)
3.5
3
Speed (cm/min)
2.5
2
1.5
1
0.5
0
Apples
Lettuce
Food Regime Type
Apples and Lettuce
Discussion
• Hypothesis:
– Snails can be conditioned to a specific food item,
and retain memory of that food item for extended
period of time.
– Proven by Teykes (1995)
Discussion
• Predictions:
– Conditioned to lettuce = prefer lettuce
– Conditioned to apple = prefer apple
– Conditioned to both = no preference
Discussion
• Based on the results:
– Reject hypothesis
• No signs for conditioning
or food preference
• In the wild:
– Leaves, stems, soft bark,
fruit, vegetables, fungi
and algae
• In lab:
– previously exposed to
lettuce
Improvements/ Future Directions
• Timing (6 days feeding, 1
day starved)
– Didn’t move, cleaning
shell, stationed on or
around the black plug
• Positioning of food in
chambers
– Make sure food accessible
(top, sides & bottom)
• Placement of snails
– Not facing food (eliminate
biases)
Conclusion
Overall:
• The snails did not demonstrate food attraction
conditioning.
• Our findings differed from Teykes(1995)
experiment
• Further research is needed
Questions?