Species that are subject to predation might be expected to evolve adaptations designed to
block detection, attack, capture and consumption by predators.
Adaptations to make detection less likely
- Forage less when detection more likely (e.g. banner-tailed kangaroo rats forage more on
moonless nights) - Remove evidence of presence- e.g. birds remove broken eggshell from nest
- Cryptic colour and behaviour
Cryptic colour and behaviour
Crouching /hiding combined with camouflage may protect an animal from predation, but
there are costs of remaining hidden- this is time lost to feeding, courting etc.
Camouflaged animals often choose a background to match their colour (e.g. pale morphs of
peppered moth prefer tree bark covered with lichen, dark morphs land on exposed bark).
Other animals including some lizards and fish (e.g. flounders) can change their colour to
suit the background.
Adaptations to make attack less likely
- Chemical defences- sprays, injections, toxins, sticky secretions
- Warning colouration advertises that an animal is poisonous (aposematism); several
species living in the same area may adopt the same colours (Mullerian mimicry); all
benefit - Batesian mimicry: mimic poisonous or dangerous animal e.g. adopt same colouration as
poisonous animal. - Associating with a protected species
e.g. anemone hermit crabs carry anemones on their shells; the anemone’s stinging tentacles
help protect the crab. As the anemone also benefits from the association (gaining food
particles as crab feeds) this is an example of mutualism - Advertising unprofitability to deter pursuit
e.g. stotting (leaping off ground) by Thompson’s gazelles when a predator is seen
Adaptations to make capture less likely
- Startle predator e.g. butterflies flash wings eye-spots, caterpillars inflate false “snake
head” - Rapid escape flight
- Group defences (see notes on Group living)
-Vigilance and sociality
-Dilution
-Shielding (“Selfish herd”)
-Confusion
-Mobbing
Adaptations to make consumption less likely
Once the animal is caught it may make a last ditch attempt to save itself
* Noxious sprays e.g. bombardier beetle
* Sticky secretions e.g. silk (e.g. black widow spider), salamanders
* Misdirecting consumers- expendable parts as lure (lizard tail), false head on abdomen of
butterfly
* Attracting competing consumers: fear screams, or release of fear chemicals into water
(minnows)
Alternative hypotheses to explain stotting
- Signal to other gazelles
-Alarm signal
-Group formation- flee together - Signal to predator
-Advertisement of unprofitability
Observations - Solitary gazelles stott
- Turn white rump to predator
- Predators more likely to abandon hunt when gazelle stots
These observations support the pursuit-deterrence hypothesis
