Symbiosis is any type of close, long-term, the relationship between two organisms. These relationships can be split into different types depending on the benefit or harm of the relationship to each organism. It is also split into two groups; obligate or facultative depending on whether, respectively, one or more of the organisms cannot survive without the other, or they can survive without the presence of the other.
Note: For some time it was argued that symbiosis should refer only to mutualism (benefit to both species), this argument has now been abandoned.
Symbiotic Relationships Between Species
|Type||Effect on Species A||Effect on Species B||Examples|
|Mutualism||Benefit||Benefit||Micro-organisms in the gut of borer larvae that may be chewing through the wood in a house benefit the borer by digesting the wood and releasing the nutrients into the gut where they can be absorbed by the borer. The borer benefits from being able to feed on otherwise indigestible wood and the micro-organisms benefit from being fed a constant supply of wood in suitable conditions for their growth and multiplication.|
|Competition||Harm||Harm||Rats and mice will compete for food and shelter within homes and other buildings. They are rarely active in the same spaces within buildings. Mice are more inquisitive and will more easily find their way into the living spaces of buildings, while rats tend to stay in roof voids, walls, sub-floors and out of the human living spaces; but they will invade those spaces when under pressure to find food or a mate.|
|Amensalism||Harm||No Effect||Think of the harmless garden beetle that wanders into the house and the human occupants accidentally stand on it. The beetle is harmed but there is no effect on the person.|
|Parasitism||Harm||Benefit||Fleas, bed bugs and other blood-sucking insects in the home benefit from the blood of the people or pets they feed on and the people or pets are harmed by the loss of blood, skin re4actions and possibly from diseases injected by the parasites during feeding.|
|Neutralism||No Effect||No Effect||This would be an unusual symbiosis as there is usually some benefit or harm to a species living in close association with another.|
|Commensalism||No Effect||Benefit||Rodents and humans could be regarded as a commensal relationship; the rats or mice benefit from the shelter from living in our buildings and sometimes they do no harm. But, if the rodents do damage to the building or contaminate our food then the relationship becomes parasitism. This points to the fact that the classifications of relationships can change.|
Have a look around your home, you may be surprised by how many symbiotic relationships you find.