Question

Why marine protozoa dont have contractile vacoule

Answer 1

Marine protozoa do not have contractile vacuole unlike fresh water protozoa because of the reason that contractile vacuole is used to store and remove excess water (due to endosmosis) which if comes in rapidly can cause the cell to burst,As marine protozoa have a hypertonic external enviorment they do not possess a problem of excess endosmosis instead they have to conserve their water content from getting lost in enviorment. 

Answer 2

Answer:

The marine protozoa do not have contractile vacuole because the marine protozoa live in a hypertonic environment. So, they do not need to store and remove excess water as in the case of freshwater protozoa.

The main function of contractile vacuole is to store and remove the excess water present in the cell. Marine protozoa do not need to remove excess water out of the cell, instead, they need to conserve water from getting lost in the hypertonic environment. Hence, they do not need contractile vacuole.