Which answer best indicates the dynamic balance of an ecosystem?
space and food vs. temperature and water
number of plants vs. number of animals
number and variety of organisms vs. changing environment
number of organisms vs. constant environment

The right answer is number and variety of organisms vs. changing environment

Global warming therefore involves a transformation of the environment that results in the disappearance and the appearance of certain habitats and, more generally, by the displacement of the geographical area that hosts the habitats required for a species. So some animals are forced to move to a more adequate climate, otherwise they will not survive.

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.