Organism That Lives on a Host
Puzzle 19 of Tools of the Trade Easy Pack
Question is: Organism That Lives on a Host
and the answer is: PARASITE
Word Meaning:
PARASITE — (biology) An organism that lives on or in another organism of a different species, deriving benefit from living on or in that other organism, while not contributing towards that other organism sufficiently to cover the cost to that other organism.
Definitions from Wiktionary.