Lecture 8: Fish as Predators and Prey Flashcards
What are the five stages of predation in fish?
Encounter and Detection
Pursuit
Attack
Capture
Ingestion
What are the main strategies fish predators use to capture prey?
Chasing: Speed-oriented (e.g., tuna).
Ambushing: Stealth attacks from hiding (e.g., pike).
Luring: Using adaptations to attract prey (e.g., anglerfish).
Stalking: Slow approach followed by attack.
What is the significance of gape size in piscivorous fish?
Gape size determines the maximum prey size a predator can ingest and is a critical factor in size-selective predation.
How do prey fish use crypsis to avoid predation?
Crypsis involves blending into the environment through:
Countershading (e.g., darker dorsal and pale ventral sides).
Transparency (e.g., larval fish).
Camouflage (e.g., flatfish changing color).
Reflection
Mimesis
Distractive coloration
Adaptive coloration
Ultra-blackness
How does shoaling behavior reduce predation risk for prey fish?
Shoaling reduces risk via: Dilution Effect: Reduces the chance of individual predation.
Confusion Effect: Makes it difficult for predators to target one fish.
What are functional responses in predator-prey dynamics?
Functional responses describe how predation rates change with prey density:
Type I: Linear increase.
Type II: Decelerating increase (most common in piscivores).
Type III: Sigmoidal curve (low predation at low densities).
What morphological adaptations help piscivorous fish capture prey?
Streamlined bodies (e.g., tuna), large mouths (e.g., bass), sharp teeth (e.g., barracuda), and lures (e.g., anglerfish).
What are the main adaptations of prey fish to escape after capture?
Prey fish use:
Spines and armor: E.g., sticklebacks.
Inflation: Pufferfish inflate their bodies.
Rapid escape movements: Quick bursts of swimming speed.
What are the ontogenetic diet shifts observed in piscivorous fish?
As piscivores grow, they transition from zooplankton to larger invertebrates and eventually to fish prey due to gape size limitations.
How does prey size selection influence piscivore feeding success?
Piscivores often target smaller prey for higher capture success, as handling time and prey escape rates increase with larger prey.
What is the role of prey switching in predator diets?
Prey switching allows piscivores to target the most abundant prey type, maintaining feeding efficiency when prey availability changes.
What is Batesian mimicry, and how do prey fish use it?
Batesian mimicry involves harmless prey resembling harmful species to deter predators. Example: Mimicry of venomous blennies.
How do predators like bluefish adapt their feeding behavior?
Bluefish can switch from whole-prey consumption to partial-prey consumption, allowing them to target larger prey sizes.
What is a size-refuge, and how does it protect prey?
A size-refuge occurs when prey grow large enough to escape predation due to gape size limitations of predators.
How do predator-prey dynamics influence ecosystem structure?
Predators regulate prey populations and prevent overgrazing.
Prey adaptations drive co-evolutionary changes.
Predator declines (e.g., cod in the Baltic Sea) can lead to mesopredator release, disrupting food webs.
