Life on earth is dependent on the interaction between which layers in the biosphere? a). the troposphere, the mesosphere, the crust b). the mesosphere, the hydrosphere, the crust c). the stratosphere, the mesosphere, the crust d ). the mantle, the hydrosphere, the crust c). the atmosphere, the hydrosphere, the crust

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.

layer 3 is younger than layer 6.