I’m going over an exam review sheet for my micro class and have a question. One of the points says to describe why halophiles must have a hypertonic environment.

Now I know that halophiles are microorganisms that require an environment high in NaCl in order to survive, and I also know that an environment high in NaCl, by definition, is hypertonic. However, I’m having problems understanding exactly WHY it is that halophiles must have that hypertonic environment. My text doesn’t go into any detail on the subject.