1. What special structures are specific to the phylums of Porifera, Cnidaria, Ctenophora, and Platyhelminthes?

The special structures of the following phylums:

Porifera: members of this phylum have special collar cells. They have cellular level of body organisation. Cnidaria: members have stinging cells on the tentacles surrounding mouth. Ctenophora: members have comb like ciliary plates for swimming. Platyhelminthes: For the first in animal kingdom, members of this phylum there is development of sensory and nervous tissue in the head region (cephalization)