1. The “0 / -” symbiotic relationship
Ammensalism
The “0 / -” symbiotic relationship

2. What is ammensalism?
Ammensalism is the ecological interaction in which an individual species harms another without obtaining benefit.
This type of symbiotic relationship is common, but not considered an important process structuring communities because they are “accidental” and do not benefit the species doing the harm
It is a 0/- relationship

3. Examples of Ammensalism
Elephants stepping on ants or leveling brush does not benefit the elephant but causes harm

4. Examples of Ammensalism
Algal blooms can lead to the death of many species of fish and other animals, however the algae do not benefit from the deaths of these individuals

5. Examples of Ammensalism
One of the best examples of ammensalism is the one established between humans and other species under extinction due to human actions like habitat devastation by fires, ecological accidents, pollution of water, etc.

6. Examples of Ammensalism
One way scientists have used ammensalism to help humans can be found in the relationship of the bread mold penicillium with bacteria. Penicillium releases a chemical called penicillin which kills bacteria without benefiting the bread mold. Luckily we use this secretion as medicine!

7. A Summary of Symbiotic Interactions
Influence of species A
- (negative)
0 (neutral/null)
+ (positive) A B
Amensalism - A B
Parasitism + - A B
Mutualism + - A B
Amensalism - A B
Commensalism +
Influence of Species B A B
Parasitism - + A B
Commensalism + A B
Mutualism + +