BIOL3046 Lecture Notes - Lecture 20: Persistence Hunting, Grouper, Peregrine Falcon
5 Jul 2018
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Department
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Animal Behaviour BIOL3046 460381099
Lecture 20: Predator vs. Prey.
Preventing attack: is the best form of defence. Swell up in size, look threatening.
Preventing capture: prey animals are adapted to moving fast. Flying species are more likely
to survive attack. Example: Unguligrade locomotion evolution increase of stride and lever
length. The more animals invest in flying fast (log slender body etc.) has a trade off with
reproduction.
Accurate locomotion: prey animals have excellent local navigational abilities. Example:
Elephant shrew. This is why translocated animals often display stress in a novel
environment.
Unpredictable locomotion: Prevents predator from predicting direction that prey animal will
take. The prey will usually run away from the predator at 120º so that they can still see the
predator. So from this it can be seen that a sudden move is good, but a surprising move is
better.
Evidence that high contrast markings, in species such as zebra, makes it hard for predators
to assess speed and direction of prey. It may suggest a pattern for motion dazzle.
Misdirecting a predators attack can limit damage. Example: tails of lizards fall off allowing
the lizard to escape. Also, a number of insects have false heads and gives a surprise when
the animal runs the other way. Eyespots in fish are used to misdirect attack, however this is
plastic and is a response to predator exposure.
Preventing capture of vulnerable young: Parental bird can also pretend to have a broken
wing, to prevent capture of juvenile.
Prevent consumption: investing heavily into physical defences, however there are trade-offs
with locomotion. Crab populations may have thicker shells, others invest in internal
chemicals, and expose these when attacked. Sea hares release two chemicals, and one of
these chemicals deactivates the chemical senses of the attacker.
Thanatosis: playing dead to become less appealing. Many species engage in this trickery.
Virginia opossum backs up its ‘dead’ signal by dropping heart rate, urinating, drooling and
secreting a horrible pheromone.
Predator interference: Injured fish let off a chemical smell that attracts more predators,
thus handling time is increased, giving the opportunity to get away.
Document Summary
Preventing attack: is the best form of defence. Preventing capture: prey animals are adapted to moving fast. Flying species are more likely to survive attack. Example: unguligrade locomotion evolution increase of stride and lever length. The more animals invest in flying fast (log slender body etc. ) has a trade off with reproduction. Accurate locomotion: prey animals have excellent local navigational abilities. This is why translocated animals often display stress in a novel environment. Unpredictable locomotion: prevents predator from predicting direction that prey animal will take. The prey will usually run away from the predator at 120 so that they can still see the predator. So from this it can be seen that a sudden move is good, but a surprising move is better. Evidence that high contrast markings, in species such as zebra, makes it hard for predators to assess speed and direction of prey. It may suggest a pattern for motion dazzle.
