Would meteorology be a useful science to apply to the study of Mercury the innermost and smallest planet.. Explain !

Yes, meteorology could be useful when studying other planets such as Mercury and Mars; atmospheric science has been extended to the field of planetary science and the study of the atmospheres of the planets of the solar system.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.