Phylum Echinodermata

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).