Zoology 

Remember;

1. All echinoderms are marine

2. The most numerous and successful are the Arthropods

3. The earthworms are "nature's plough man" since they tilt the soil aerate it.

4. In earthworms,each segment has a separate coelom and acts as a hydraulic skeleton.

5. All Arthropods have an exoskeleton of chitinous cuticle