someone who studies relations of organisms
There are many types of biologists. Some work on microorganisms, while others study multicellular organisms. There is much overlap between different fields of biology such as botany, zoology, microbiology, genetics and evolutionary biology, and it is often difficult to classify a biologist as only one of them.
What is the relationship between two organisms called? The term that you are referring to is symbiosis. (a symbiotic  relationship)    Symbiosis (from Ancient Greek ÏÏÎ½ together and Î²Î¯ÏÏÎ¹Ï living)  is a proxiâ¦mate and often long-term interaction between two or more  different biological species.