Earth Science

Life on Earth

Roles in an Ecosystem

Study Tip
Think about Latin roots to remember what consumers eat.
Herba (herbivore): small plant
Carne (carnivore): flesh
Omni (omnivore): all

Roles in Ecosystems

Climate conditions determine which ecosystems are found in a particular location. A biome encompasses all of the ecosystems that have similar climate and organisms. Different organisms live in different types of ecosystems because they are adapted to different conditions.

Study Tip
Think about Latin roots to remember what consumers eat.
Herba (herbivore): small plant
Carne (carnivore): flesh
Omni (omnivore): all

Nevertheless, every ecosystem has the same general roles which living creatures fill.

  • Organisms that produce their own food are called producers. There are 2 ways of producing food energy:
  • Photosynthesis: plants on land, phytoplankton in the surface ocean, and some other organisms
  • Chemosynthesis: bacteria at hydrothermal vents
  • Organisms that use the food energy that was created by producers are named consumers. There are many types of consumer:
  • Herbivores eat producers directly. These animals break down the plant structures to get the materials and energy they need
  • Carnivores eat animals; they can eat herbivores or other carnivores.
  • Omnivores eat plants and animals as well as fungi, bacteria, and organisms from the other kingdoms.
llama grazes
A llama grazes on a terrace near Machu Picchu, Peru
  • There are many types of feeding relationships between organisms.
  • Predator: animal that kills and eats another animal, known as its prey
  • Scavengers: animals that eat organisms that are already dead (e.g. vultures and hawks)
  • Decomposers: break apart dead organisms or the waste material of living organisms, returning the nutrients to the ecosystem

(a) Predator and prey; (b) Scavengers; (c) Bacteria and fungi, acting as decomposers.

Earth Science

  • Species have different types of relationships with each other.
  • Competition occurs between species that try to use the same resources.
  • When there is too much competition, one species may move or adapt so that it uses slightly different resources.
  • If the competition does not end, one species will die out. Each niche can only be inhabited by one species.
(a) The pollinator gets food; the plant’s pollen gets caught in the bird’s feathers so it is spread to far away flowers. (b) The barnacles receive protection and get to move to new locations; the whale is not harmed. (c) These tiny mites are parasitic and consume the insect called a harvestman.
Concept Check
  • Compare and contrast the two different ways of producing food energy, photosynthesis and chemosynthesis.
  • After a producer produces food energy, follow its path until it ends up being used by another producer.
  • What kind of symbiotic relationship do zooxanthellae and corals have?