The $Bipinnaria$ larva is found in:

Water vascular system (ambulacral system) is found in ...................

Radial symmetry occurs in

Absence of excretory organs,great power of regeneration,and exclusively marine animals belong to the phylum:

Water vascular system is present in $:-$

Assertion : Ambulacral system plays a major role in locomotion of echinoderm.
Reason : Hydraulic pressure of fluid and contraction of muscle of tube feet make possible movement of echinoderm.