Populations in a Community
Food Webs
Population: all the organisms of the same species that live in the same place at the same time
A group of frogs living in a pond
Community: multiple populations that live in the same place at the same time
Groups of fish, frogs, ducks, and lily pads that live in a pond
Food web: a diagram that shows what eats what in a community
Levels of a food web:
Producers: take in the sun’s energy and make their own food (examples: plants, algae)
Consumers
Primary consumers: herbivores that eat producers for energy (examples: rabbits, cows, deer)
Secondary consumers: carnivores that eat primary consumers (examples: lions, tigers)
Tertiary consumers eat secondary consumers and so on
Animals can belong to multiple levels of a food web: omnivores eat both producers (plants) and consumers (animals) (examples: foxes, bears)
Decomposers: an organism that breaks down dead bodies of organisms at every level (examples: mushrooms, bacteria)
Niche: the function that an organism performs in the food web of that community, as well as everything the organism does and needs in its environment
No two types of organisms occupy exactly the same niche in a community
Relationships Between Organisms
A symbiotic relationship may exist between two organisms of different species when they live and work together.
Mutualism: both organisms benefit
Clownfish and anemones: the clownfish gets a safe habitat in the anemone while the anemone gets food because the clownfish’s bright colors attract other fish
Commensalism: one organism benefits and the other is unaffected
Barnacles and humpback whales: barnacles get a ride on the whales, but the whales are not affected
Parasitism: one organism benefits and the other is harmed
Tapeworms and humans: tapeworms attach themselves to human intestines and get food, but humans are harmed
Predator-prey relationship: the interaction between a consumer that hunts for another consumer for food (for example: a fox, the predator, eating a rabbit, the prey)
Competition: two populations both use a resource, so they must fight for it
Cooperation: two populations work together to get a resource
Communities are interdependent because organisms and populations depend on other organisms and population for food or other resources. Energy resources of a community are shared through the interactions of producers, consumers, and decomposers.