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
Crows + Hypothesis + Prediction
Hypothesis: Crows attempt to maximize energy intake rate according to the optimal diet model
Prediction: Crows should eat all clams greater than 29 mm in size and reject all clams < 29 mm in size.
Crows + Methods
Methods:
Recorded the size of clams that were eaten and the size of clams picked up but not eaten (rejected)
Measured handling times of differently size clams
Measured energy content of differently size clams
Crows + Results
Clams > 30 mm were almost always eaten
Clams < 28 mm were almost always rejected
