Sea stars and sea cucumbers are chiefly marine invertebrates with bodies covered in spines. They have a water vascular system called an ambulacral system that functions for locomotion, respiration, and feeding. Their bodies are differentiated into tissues and organs, with sex organs found in each arm. They also have remarkable regeneration powers, with sea stars able to regenerate lost arms and sea cucumbers able to discharge internal organs if threatened.

2. Chiefly marine invertebrates
Bodies are covered with spine,
a characteristic by which they
are described (Greek: echinos
= hedgehog; derma = skin)

3.  Have a water vascular system a.k.a
ambulacral system, which function
for locomotion, respiration and
feeding.
 The body is trisemic and well
differentiated into tissues and
organs.
 Their sex organs are found in each
arm

4.  They have remarkable powers of
regeneration.
 Some sea stars are capable of
regenerating lost arms.
 Sea cucumbers often discharge parts of
their internal organs if they perceive
danger (a phenomenon called
evisceration).