Which of the following set of characteristics accurately describes the phylum cnidaria?

a. radial symmetry with only two germ layers and one digestive opening

b. asymmetric and porous body plans

c. cylindrical bodies with bilateral symmetry and two digestive openings

d. flat bodied with three germ layers and a single digestive opening

The correct answer is A. radial symmetry with only two germ layers and one digestive opening.

Explanation:

Phylum Cnidaria consist of aquatic organisms and they have special feature called Cnidocytes. Cnidocytes are tentacles used to capture the pray. All organisms of phylum are bilateral and have two body layers called Endoderm and Ectoderm. A jelly like material called mesoglea is present between ectoderm and endoderm. Their digestive system has no organs and their is a single opening to capture the food. As they have only single opening in digestive system it is also used to excrete the digested food out of the body.  

a symbiotic relationship with the mitochondria