Animals that exhibit bilateral symmetry in the larval stage and radial (pentamerous) symmetry in the adult stage belong to the phylum:

In which animal is the water vascular system found?

Starfish belongs to the class:

Aristotle's lantern is found 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.

Respiration by dermal gills $(branchiae)$ and respiratory tree is performed by the animals of