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How Organisms Make a Living



Energy in the form of food is the key to staying alive.


Every living thing has to have ways to get energy.


In human life, this process is called "Making a Living."


"putting together"

Life's second great invention was to find a way to use light to make a living.


Photosynthesis transforms radiant light energy into chemical energy.


Photosynthesis is a way of packaging and storing energy that originated in the sun.

How do organisms make a living?
Here are eight basic paths

The Green Way

Plants on land, and algae and cyanobacteria in water, absorb sunlight and transform it into chemical energy.
These Producers package the sunlight energy as food we call carbohydrates.
Producers depend on sunlight


Grazing & Browsing:

A Gentle Way

Animals such as snails, deer, grasshoppers, rabbits and monkeys eat leaves, usually without killing the plants. Many others eat seeds, flowers and fruits.
These primary consumers package the sunlight energy as a mixture of proteins and fats we call meat.

Primary consumers
depend on plants and algae.

The Carnivorous Way

Carnivorous animals such as frogs, shrews, snakes, owls, skunks, ladybird beetles and mink, kill and eat other animals.
These secondary consumers package the sunlight energy as a mixture of proteins and fats we call meat.
Predators depend on grazers and browsers and on other predators.
A Lazy Way

Parasitic plants and animals, such as mistletoe and leeches, take food from other organisms, usually without killing them, but give nothing in return.
Parasites usually live attached to, or inside, the host organism.
Most parasites depend on a single host species they
co-evolved with.
The Win-Win Way
Symbiotic organisms combine to live mutually so that both partners benefit.
Plant and animal cells, (yes, your cells) originated as a symbiosis of different kinds of bacteria.
Virtually all plants combine their roots with symbiotic fungi (mycorrhiza) to help them absorb nutrients. Also see
Plants: Rizosphere and Mycorrhiza

Symbionts (symbiotic partners) depend on each other.
Detritus--Feeding: A Clean-Up Way Detritus is organic particles left after plants or animals are partially decomposed. Earthworms and many oceanic bottom-dwelling worms are detritus feeders and play a vital role in re-cycling organisms. Soil insects, such as springtails, and fungi are alsodetritus feeders.
Detritus-feeders depend on dead organisms, mostly plants.

Scavenging: A Necessary Way
Scavengers, such as vultures and jackals, feed on dead animals. They are carnivores who wait to feed until their prey are dead. Many carnivores are part-time scavengers.
Scavengers prepare bodies for decomposers.
Scavengers depend on non-microscopic dead animals.
Decomposing: The Recycling Way Many bacteria and fungi feed on dead organisms and break them down into their chemical parts.
Decomposers restore life-materials to the ecological nutrient cycles and prepare them for re-use.
Decomposers depend on dead organisms of all sizes.




Explore Further in Energy

frog   Energy: Introduction
frog   Energy: Energy Transfers from Life to Life

top of page

Explore the Biosphere

Biosphere: Introduction
Biosphere as Place: Introduction
Biosphere as Ocean: Life Zones
Biosphere as Ocean Floor: Benthic Biomes One
Biosphere as Ocean Floor: Benthic Biomes Two
Biosphere on Land: Terrestrial Biomes
Biosphere on Land: Anthropogenic Biomes
Biosphere as Process: Introduction
Biosphere Process: Floating Continents, Tectonic Plates
Biosphere Process: Photosynthesis
Biosphere Process: Life Helps Make Earth's Crust
Biosphere Process:
Rock Cycle--Marriage of Water and Rock
Biosphere Process: Marriage of Wind and Water
Biosphere Process: Gas Exchange
Biosphere as An Expression of Spirit
The Ecological Function of Art
The Earth Goddess
The Tree of Life
The Green Man
Earth Art
Biosphere as Community
Biosphere Microcosm: Bacteria and Archaea
The Procaryote Domain
Biosphere Microcosm: Germs
Biosphere Community: The Eucaryote Domain
Biosphere Community: Protists 1: Algae
  Biosphere Community: Protists 2: Protozoa
Biosphere Community: Plants: What's New?
Biosphere Community: Kinds of Plants--Major Groups
Biosphere Community: Plant Defense
Biosphere Community: Plant Pollination
Biosphere Community: Plant Seed Dispersal
Biosphere Community: Kingdom Animals
Biosphere Community: Kingdom Fungi
Biosphere Community: Six Great Extinctions
Return to Ecology Index


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