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Interactions
Among
Living
Things
The trap jaw ant closes its mouth the fastest. It
closes its mouth in 0.13 milliseconds at speeds of
35 to 64 meters per second! The force created
when its jaw snaps shut helps the ant escape
danger by either jumping up to 8.3 centimeters
high or 39.6 cm sideways.
1. How does the trap-jaw ant’s adaptation help it
avoid becoming the prey of another organism?
2. What are some adaptations that other predators
have to capture prey?
Adaptations
Behaviors and physical characteristics
that allow organisms to live
successfully in their environment
Example of adaptations
• Arctic hare: fur changes from gray to white in
winter
Niche
• The role of an organism in its habitat
• What it eats, how it gets food, and what eats
it
Your turn…
3. Describe the niche of a squirrel.
4. What adaptations might a squirrel have that
make it able to live in its environment?
Interactions Among Living Things
• Competition, Predation, Symbiosis
Competition
If two species occupy the same niche, one of the
species might eventually die off because of
competition.
Competition: the struggle between organisms to
survive as they attempt to use the same
limited resources
Predation
Interaction in which one organism kills another for
food or nutrients
Predator: the organism that does the killing
Prey: the organism that is killed
Your turn…
5. Imagine an ideal predator to prey upon a
porcupine. Draw or describe your predator and
label its adaptations.
Predator Adaptations
• Cheetah: runs fast for short time
• Owls: can hunt at night
Prey adaptations
Skunk: Smell
Porcupine: sharp quills
Stopping to think…
6. Two main ways in which organisms interact
are ____________ and ________________.
7. Give an example of competition.
8. Owls often prey on mice. What adaptations
do you think mice have that help them avoid
becoming prey?
Symbiosis
• Any relationship in which two species live
closely together and at least one benefits
• 3 kinds are mutualism, commensalism,
parasitism
Mutualism
• Both species benefit
• Examples: An oxpecker rides and snacks aboard
an impala. The oxpecker eats ticks living on the
impala’s ears.
Your turn…
9. How does the oxpecker benefit?
10. How does the impala benefit?
11. Explain how the relationship between a
hummingbird and flower is mutualism?
Commensalism
• One species benefits and the other is neither
helped nor harmed
• A bird builds a nest in a tree. The bird gets a
place to live while the tree is unharmed.
• This is not very common in nature.
Parasitism
• A relationship that involves one organism
living with, on, or inside another organism and
harms it
• Parasite: the organism that benefits
• Host: organism that it lives on or in
• Example: fleas on a dog