Mention one example each for animals with chitinous exoskeleton and those covered by a calcareous shell.
Every living form maintain a proper shape, size and structure. In multicellular lower organisms the shape of body is maintained by certain biological materials like chitin and calcium substances. Chitinous exoskeleton is the characteristic feature of arthropods. (e.g., cockroach, termite,wasp) whereas, calcareous shell is present in molluscs (gastropods). (e.g., snail and slugs).
