Question

what do porifera (sponges), ctenophora (comb jellies) and cnidaria (jellyfish, corals, anemones, and hydroids) have in common regarding symmetry?

Answer 1

They are non-bilaterian.

Step-by-step explanation:

All the animals you listed are non-bilaterian; any organism that lacks bilateral symmetry is non-bilaterian, which is what all of those have in common.