(a) Fungi cause decay by releasing enzymes onto the dead animal or plant. These break down complex compounds into simple soluble ones that can be absorbed by decomposers. Organisms that feed on dead material in this way are called saprophytes.
(b) Platyhelminths or flatworms are called so because they are dorsoventrally flattened.
(c) Birds have thin, hollow bones to lighten their weight and make it easier for them to fly.