Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment contains a higher concentration of solutes than the protozoan. is isotonic to the protozoan. is hypertonic to the protozoan. is hypotonic to the protozoan.