What are the six classes of living echinoderms and the types of animals in each class?

The six classes of living echinoderms are:

1. Asteroidea - sea stars (starfish).
2. Ophiuroidea - brittle stars and basket stars.
3. Echinoidea - sea urchins and sand dollars.
4. Holothuroidea - sea cucumbers.
5. Crinoidea - sea lilies and feather stars.
6. Concentricycloidea - sea daisies.

Each class exhibits unique adaptations and forms, contributing to the diversity of this marine phylum.