Marine protozoa dont have a contractile vacuole why?

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.

because the light is a great source of energy for the plants to survive. (i hope this )