Characteristic of echinoderm

Answer 1

1. Deuterostome embryo development
2. Secondary radial symmetry: larvae have bilateral symmetry (radial symmetry thought to have evolved from sessile forms)
3. Five radial parts; sea urchins and cucumbers by folding "arms" upwards and fusing their edges; sea cucumbers lay on "side" and developed pseudo-bilateral symmetry, i.e. have distinct upper and lower side
4. Endoskeleton: calcite plates = ossicles, covered by epidermis, may be single plates (flexible body) or fused (solid shell, sea urchin)
5. Spines on calcite plates give "spiny skin" (phylum name!) sea urchin spines are endoskeleton and covered by thin skin!

Answer 2

some examples of echinoderms are:

1) Starfish

2) Sea Urchin

a starfish sticks to walls