Why can algal blooms be dangerous? a. Some dinoflagellate species synthesize toxins.
b. Too much algae can limit photosynthesis.
c. dinoflagellates use up needed oxygen
d. Algae produce methane.
e. Too much algae causes pollution.

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 answer to your question is slate