Final answer:
The symbiotic relationship where one organism benefits and the other is neither harmed nor benefited is called commensalism, which is different from mutualism, where both organisms benefit, and parasitism, where one benefits at the expense of the other.
Step-by-step explanation:
The term used to describe a symbiotic relationship where one organism benefits but the second organism is neither harmed nor receives any benefit is known as commensalism. In such relationships, one species typically uses the other for a purpose other than food or nectar, such as transportation or shelter, exemplified by mites hitching a ride on larger insects or hermit crabs living in the shells of dead snails.
On the other hand, a symbiotic relationship where both coexisting species benefit from the interaction is called mutualism. In contrast, parasitism is a relationship where one species benefits at the expense of the other, causing harm.