There so many different relationships existing in an ecosystem. The most common ones are symbiotic and parasitic relationship. The parasitic is harmful to the host but the symbiotic relationship has both organisms benefiting.
An example of commensalism in the marine ecosystem is that of the remora and whales. Remora attach themselves to the whales and ride and eat scraps, but the whales neither gain nor are harmed by this relationship.
The biological relationships existing amount the organisms are Mutualism, Parasitism, Communalism and Amensalism. A tick is an example of the parasitism relationship, while a tick bird on a rhino represents a mutualism relationship.
A symbiotic relationship is the same as a mutualistic relationship, where both organisms benefit- For example, lions hunting for food- this enables a vast group of organisms to benefit and means that resources can be shared