Chapter 8 - Experiments Flashcards
Catfish + RQ
How do nocturnal (Silurus glanis) catfish find food in the dark?
Catfish + Hypothesis + Prediction
Hypothesis: Catfish use their lateral line system to detect cues provided by the wake of their fish prey
Prediction: Catfish will follow the wake of their prey while hunting
Catfish + Methods
Observed catfish hunting individual guppies
Used an infrared video system to track the movement of both predator and prey in complete darkness
Classified movement sequences as “path following,” “head-on encounters,” or “attack on stationary guppy”
Path following = the catfish followed the guppy wake
Head on encounters = the catfish encountered the guppy head-on without a previous encounter
Catfish + Results + Conclusion
Results: 80% of attacks occurred on moving guppies
Catfish usually followed the same path as the guppy before the attack
Conclusion: Catfish appear to follow the path of their prey to find and attack them
Catfish (Chemical) + RQ
Do catfish use chemical or hydrodynamic cues to track their prey in the dark?
Catfish (Chemical) + Methods
Used an infrared video system to track the movement
Manipulated either the lateral line or external gustation
Classified hunting success and movement sequences of treatment fish
Hydrodynamic info: immerse the fish in a solution of cobalt chloride
External gustation: surgically remove a portion of the medulla oblongata
Catfish (Chemical) + Results + Conclusion
Results: Without lateral line, mostly head-on attacks and low capture rate
Conclusion: The lateral line provides important information for catfish to track the wake of their prey
Bees + RQ
Is foraging more efficient when multiple sense are used
Bees + Methods
Trained individual bees (Bombus impatiens) to feed on artificial flowers
Treatments
1. Visual Cue
2. Olfactory Cue
3. Shape and Olfactory Cue
Bees + Results + Conclusion
Bees trained to use both visual and odour cues had the highest feeding performance
Conclusion: The use of multiple sensory cues facilitates efficient feeding
Cryptic Prey + RQ
: How does cryptic prey colouration affect trout foraging efficieny?
Cryptic Prey + Hypothesis + Prediction
Hypotheses: Prey that match their background will be harder for predators to detect, and predator hunting efficiency will increase with experience.
Predictions: [1] Trout will find noncryptic prey faster than they will find cryptic prey. [2] Trout will find cryptic prey faster with experience.
Cryptic Prey + Methods
- Established two test aquaria, identical except for the colour of the aquarium bottom: one was brown plastic covered with brown grains, and the other was green plastic covered with green grains.
- Placed a single prey (a maggot) in one of six different locations on the aquarium bottom. The maggot was cryptic on the brown background and conspicuous on the green background.
- Recorded the amount of time until the test fish found the food item
- Tested 42 parr (i.e., young trout), half with cryptic prey and half with conspicuous prey
Cryptic Prey + Results + Conclusion
Results: Individuals found noncryptic prey faster than cryptic prey. Search times to find prey decreased with experience.
Conclusions: Background color matching can benefit prey by reducing predator hunting efficiency. Predator search efficiency for cryptic prey can increase over time.
Crows + RQ
Why do northwestern crows reject some clams while foraging
