Answer: Body plans change as new challenges arise.
Step-by-step explanation:
The mollusks are the invertebrate animals. They live marine environment. They live in shallow waters. They have been found in variety of marine habitats so this indicates their adaptiveness to different conditions. They have body plan that comprises of shell, mantle, radula and muscular foot that helps in survival and adaptation in different conditions. The shell and mantle are hard structures which protect these animals from predators and also help them to camouflage. Also the muscular foot helps in locomotion. Radula helps in feeding. Oysters, snails are some examples of mollusks.