1. Lesson 1.4: Interactions within an Ecosystem

2. Interactions within an Ecosystem:
Predation: occurs when one organism hunts (predator) another organism (prey) to consume
Example: A leopard seal (predator) hunts and eats an emperor penguin (prey) in Antarctica.

3. Interactions within an Ecosystem:
Competition: fighting over a resource such as food, shelter, or a mate; can occur 2 ways:
Intraspecific: between the same species
Ex. Hermit crabs compete for the biggest shell
Interspecific: between different species
Ex. Sponges & coral compete for food on the reef

4. Interactions within an Ecosystem:
Keystone Species: a species that has vital importance to its ecosystem; without the keystone species, the ecosystem would be drastically different
Ex. Sea Otter – is a keystone species in a kelp forest. Sea otters feed on sea urchins, which feed on kelp. Without the sea otter, the sea urchins would over populate. If there are too many sea urchins, there would eventually be no more kelp forest!

5. Interactions within an Ecosystem:
Invasive Species: a non-native species that causes harm to an ecosystem it was introduced to
Ex. Florida- Lion Fish in the reefs and Pythons in the Everglades have no natural predators, breed exponentially, and continually feed on native species, destroying the balance of the ecosystem

6. Interactions within an Ecosystem:
Symbiosis: “living together” occurs when 2 different species have a close relationship within an ecosystem.
3 types:
Mutualism
Commensalism
Parasitism

7. Types of Symbiosis:
Mutualism: occurs when both species in the relationship benefit in some way
Ex. Clownfish & sea anemone – fish gets a free home & also provides waste (food) for the anemone to eat.

8. Types of Symbiosis:
Commensalism: occurs when 1 organism in the relationship benefits without affecting the other one
Ex. The remora fish attaches himself to a shark to gain a free ride & protection from predators, the shark doesn’t mind (the fish is too small to even be a snack!)

9. Types of Symbiosis:
Parasitism: occurs when 1 organism in the relationship benefits while harming the other one
Ex. A tapeworm lives inside a polar bears gut and feeds off his internal organs.