What does it mean to say that cells are “specialized”?

Hope this helps !!!

Explanation:

A cell is the basic unit of life. However, there are many different types of specialized cells. This means they are modified by size, shape, or function according to their purpose. Specialized cells make up tissues, tissues make up organs, and organs make up the systems that work together to make up our bodies.

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.