The evolution of an internal body cavity was in important improvement in animals body design in which area ?

In molluscs, the general body cavity is

Functional body cavity in arthropods is

Body cavity is lined by mesoderm in

A body cavity which is lined by mesoderm is called

Give scientific terms for the following : (a) True internal body cavity of animals (b) A solid, unjointed rod present in chordates at some stage of life. (c) Creeping vertebrates. (d) Pore-bearing animals

Name the body cavity of Nematodes.