What type of symmetry is associated with diploblastic organisms? Which phylum is the exception to this rule and why?

Answer: Diploblastic animals have radial symmetry.

Phylum porifera lack body symmetry and are therefore call asymmetrical this is because their bodies lack true tissues, true organs and there body is well adapted for water and water flows through their body and deposit nutrients needed for growth and development.

Explanation:

Diploblastic organisms meaning organisms that have two germ layers (ectoderm and endoderm) have radial symmetry because their symmetry is located along a central axis examples are the sea anemone and jelly fishes belonging to phylum cnidarians.

Phylum porifera e. g sponges are assymetrical that is they have no body plans and this is because the shapes of their bodies is adapted to water and water flow allow nutrients to enter their body for growth.