Sensory Ecology 2: Predation and Aggression

Sensory Ecology 2: Predation and Aggression

1. Find Food - Predator-Prey Interactions

   • Visual cues can be used to detect prey
     • Thee cues may be obscured by the complex habitat
     • Prey is also under selection pressure to not be detected
       • Use camoflage or crypsis
         • Prey that is detected show rapid response times
     • Predators use many different senses to detect prey
   • Predation strategies
     • Ambush Predators
       • These predators will wait for mobile, abundant prey to come into their active capture area
         • E.g. spotted stargazers who hide in burrows and use their lateral line to detect wake of prey in water
     • Criise Predation
       • Predators move through the water to capture less abundant prey
         • Prey is normally evenly distributed throughout water column
   • Saltatory Predation
     • Predation where predator will move and wait, move and wait.
       • eventually prey will move into the animals active capture area
       • Basset et al (2007) looked into the predation strategy of scorpionfish
         • Porcelain crabs are small and uptake water through scathognathies
           • fish have to move and wait so as to detect crab breathing (interference)
         • Prey is not abundant so cant ambush
         • Scorpionfish detect water currents through lateral line

2. Avoid Detection

   • Background matching
     • Hermit Crabs occupying empty gastropod shells
       • Given choice of either light or dark shells on an either light or dark background.
       • Initially crabs just pick whatever shell is closest regardless of background match
         • After 24 hours crabs have changed choice to shell that matches background.
         • In dark backgrounds crabs only changed shell to match when there was a predator cue
   • Counter-shading
     • Reef sharks have two different colourations on their bodies
       • Light underneath so prey below cannot see when they look up.
       • Dark topside so that prey/predators above cannot see from above
   • Disruptive colouration
     • Animals trying to break up their colouration (stripes)
       • E.g. Spotted Drumfish
     • This breaks up the outline of the animal in complex habitats
       • Useful for avoiding detection
   • Colour change in Cephalopods
     • Cephalopods have been known to change colour based on their background
       • Carry out this process using chromatophores
       • Eg Cuttlefish

3. Decision making and Competition

   • Briffa et al (1998) Decision to give up in hermit crab fights.
     • Successful attackers rap on shell more vigorously than ones that give up
     • When a crab is evicted the last rapping bout will have been strongest
       • If a competitor doesn't give u shell rapping strength decreases
   • Hypoxic conditions cause attackers to rap slower and causes them to give up easier