Answer: opportunistic

AnswerCrossword Clue
opportunisticExploiting chances offered by immediate circumstances without reference to a general plan or moral principle
opportunistic(of a plant or animal) Able to spread quickly in a previously unexploited habitat
opportunistictaking advantage of opportunities as they arise
opportunistic(of a microorganism or an infection caused by it) Rarely affecting patients except in unusual circumstances, typically when the immune system is depressed