Download Document

Unit 2 Making a Living in the
Wild
Chapter 7
Predators and Prey
Predators and Prey
• Predators are
organisms that survive
by eating others
(includes some plants
and fungi)
• Prey is what they eat
• Coevolution- changes in
both pred and prey due
to their interactions
Predator Behaviors
• Prey selection- use
experience to choose
what to hunt
• Locating prey by vision,
hear, smell
• One sense dominates
the others
Examples
• Dolphins and bats
use echolocationsound waves
• Some animals use
vibrations in ground
or water or body
heat
• Some use electrical
fields in the water
(sharks) called
ampullae of
Lorenzini
Capturing prey
• 1. Stalk and
ambush- cats
• 2. Consistent
pursuit- chimp hunt
• 3. Lure in preyangler fish, less
common
Hunting in groups
•
•
•
•
Social carnivores
Can hunt larger prey
Then must share
Can use group as
defense as well
Group predation in other
species
• Not just large
carnivores
• Hawks
• Humpback whales
• Killer whales
• Spiders
• Ants
Handling prey
• Immobilize (stun)
• Kill immediately and
take somewhere
else and eat right
away
• Store kill for later
(cache)
Defense against predation
•
•
•
•
Primary vs. secondary
Primary- built into body
Ex: spines
Secondary- behavior
when faced with
predator
• Ex: run away, spray
toxins
Primary defenses
• 1. Camouflage
• 2. Warning displays (aposematism)coloration
• Mimicry (2 types)
• Mertensian- resemble something dangerous
• Batesian- resemble something unpalatable
• Mullerian mimicry- two unpalatable animals
resemble each other
Primary defense cont
• 4. Lifestyleavoidance, live in
large numbers, etc
Secondary defenses
• 1. Flight- get away
quickly
• Flagging behavior-act
hurt to distract predator
from young
• 2. Fight- usually when
cornered, toxins
• Mobbing- diving and
chirping loud to distract
predator from young
Secondary defense
• 3. Freeze- silent,
odorless, even may
lose consciousness
(tonic immobility)
Evolutionary arms race
• The better prey is at surviving, the
better the predator must be to catch it
• Population size fluctuates in cycles
• Both pred and prey usually stay stable
• Prey usually reproduce faster than pred
• Predators invest more in their young b/c
have longer lifespan