Remoras are fish that attach themselves to the underside of larger organisms, such as sharks. Remoras benefit by using the shark for protection, transportation, and food. The
shark neither benefits nor is harmed. This is an example of -
mutualism
commensalism.
predation.
parasitism.

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.

the correct answer in apex is tissue development, i know because i just had this question