Symbiosis

Basic Information

This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand.

Soon after aerobic bacteria appeared, something special began to happen to life. Perhaps it began at the surface of the mud, where the anaerobes were still hiding away from the oxygen poison.
An anaerobe in the mud passed its oxygen molecules and its own wastes to an aerobe in the water. In return the aerobe passed back chemicals rich in ATP. Both bacteria gained. The aerobe got extra food. The anaerobe got energy.
When things live together like this, both benefiting from the arrangement, it is called symbiosis. Both partners benefit from the relationship. Neither could survive without the other.

Examples of symbiosis on Earth today are:

fungi and algae or blue-green bacteria live together in lichen;
nitrogen-fixing bacteria live in the roots of beans;
cows and the bacteria which live in their stomachs;
tree roots and fungi (mycorrhiza);
flagellated protozoa digest the wood eaten by termites;
acacia ants live in the bull-horn acacia -- the ants get food and shelter, the acacia gets protection from browsing animals which the ants drive away;
the yucca moth depends upon the yucca plant -- the moth pollinates the plant as she lays her eggs in the seed pods of the yucca, the larvae hatch and feed on some but not all the seeds.

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Earlier 1.5 Billion Years ago Later

Biological Environment > Symbiosis

Basic Information