In the heart, one ventricle pushes blood with oxygen to the cells of the body. where does the other ventricle push the blood without oxygen?

The other ventricle which is right ventricle receives deoxygenated (blood without oxygen) blood from the right ventricle. Right ventricle pushes deoxygenated to the lungs for the oxygenation through pulmonary artery. Although artery carries blood with oxygen but pulmonary artery is exception as it carries blood without oxygen. This is a part of pulmonary circulation.

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.