How symmetry and nervous system typified in echinoderms

Question

How symmetry and nervous system typified in echinoderms?

Answer 1

Adult echinoderms, along with the cnidarians, are animals which present radial symmetry, that is, their body structures are distributed around the center. Radial symmetry in echinoderms but is a secondary radial symmetry, because their larval stage has bilateral symmetry and radial pattern seems only in the adult individuals (there are some few adult echinoderms with the lateral symmetry). All other animals encompass lateral symmetry with exception of the poriferans (no symmetry is defined for them).

Echinoderms don’t present cephalization and they have a diffuse network of the nerves and the neurons which is made of a neural ring around mouth and of radial nerves which ramify to follow pentaradial structure of body.