How does the support structure of echinoderms differ from that of arthropods?

The primary difference between arthropods and echinoderms is their covering. Arthropods have a tough, non-living outer shell called exoskeleton, which protect their soft bodies while echinoderms have living endoskeletons, which develop within the deeper skin or body tissues and act as their protective covering. Echinoderms :

1) Marine

2) Adults are radially symmetrical but larvae are bilaterally symmetrical

3) Respiration through dermal bronchiae, tube feet, respiratory tree or bursae.

4) Circulation by water vascular system(open type)

5) Complete digestive system

6) Specialized excretory organ absent.

7) Brain is absent.

8) Unisexual , without sexual dimorphism , external fertilization and always indirect development.

Arthropoda :

1) All habitats ( almost all )

2) Bilateral symmetry

3) Respiration by general body surface, gills, trachea or book lungs

4) Blood vascular system (open type)

5) Complete digestive system ( extracellular inside the digestive tract)

6) Excretion through malpighian tubules, green gland, coxal gland

7) Nervous system is made up of nerve ring and double, ventral and solid nerve chord.

8) Mostly dioecious. Fertilization is usually internal.

Explanation:

the real answer is b. scintillation counter

the farther away the object is from the central star (the sun) it's gravitainal pull on the object is weaker when it is farther

explanation: