1.They have a unsegmented body.
2.Body cavity is present which is well developed and modified into water vascular system.
3.They have a spiny exoskeleton.
4.They have tube feet which help in locomotion.
5.They have a radiallysymmetrical body.
6.They are triploblastic animals that is they have three body walls

The features of Echinodermata are as follows:-
.Echinoderms are radially symmetrical, triploblastic coelomate animals
.Their body is either star-shaped, spherical or cylindrical.
.Their body surface is covered with calcareous spines or projections.
.They do not have head and tail or right and left sides.
.They have coelom which is well-developed and modified into water vascular system.
.They have tube feets for locomotion
eg: starfish, sealily etc.

hoped helped u :))