Bacteria in our intestinal systems. They help us break down things/food that we could not simply by our stomach grinding and acids. We give them food.
No, not all symbiotic organisms are harmless to humans. Some symbiotic organisms can be harmful and cause infections, diseases, or other health issues in humans. It is essential to understand the specific relationship between the host and the symbiotic organism to determine if it is beneficial or harmful.
The smaller organism is referred to as the symbiont, while the larger organism is referred to as the host in a symbiotic relationship.
host
A Shark
commesalism
Neutralism - this refers to the relationship where neither organism extracts benefit but neither are they harmed by co-existing
A symbiotic relationship called Parasitism.
House Sparrows have been known to have a commensal relationship with humans. They benefit from nesting in man-made structures and feeding on human-provided food sources, while humans usually do not benefit or harm from the presence of House Sparrows.
This is an example of a parisitic relationship because the organism harms the host.
Symbiotic.
Mutualism humans
The only roundworms that have a symbiotic relationship with humans live in our digestive tracts. They absorb nutrients and release toxic waste without giving us any benefit. Thus, roundworms have a parasitic relationship with humans. Technically parasitism (one organism benefits, the other is harmed) is considered a different form of interaction between species as symbiosis (both organisms benefited). The other possibility is commensalism (one organism benefits, the other is not affected).