Living representatives of Echinodermata include : Sea
Lilies, Starfish, Bristle Stars, Sea Urchins, and Sea Cucumbers.
They are
the largest phylum to lack any freshwater or land representatives.
Most are
pentamemal, meaning that they have fivefold symmetry, with rays or arms in fives
or multiples of five.
Many
fossil Echinoderms were not pentameral.
Many
Echinoderms form “Tube Feet”, with which they can move or grip with.
The
oldest known Echinoderm is the Vendian Fossil.
All
echinoderms are marine; they cannot live in freshwater or on land.
They
range from a few millimeters to a few decimeters in size.