What is the adaptive value of having the organ of gas exchange (the alveolus) inside the body?

For gaseous exchange and energy distribution

Explanation:

they give the lungs a really big surface area.

they have moist, thin walls (just one cell thick)

they have a lot of tiny blood vessels called capillaries

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.