What type of symmetry do echinoderms show?
parallel
mirrored
lateral
radial
As mentioned earlier, echinoderms show radial symmetry. Other key echinoderm features include an internal skeleton and spines, as well as a few organs and organ systems. Although echinoderms look like they have a hard exterior, they do not have an external skeleton. Instead, a thin outer skin covers an internal skeleton made of tiny plates and spines. This provides rigid support. Some groups of echinoderms, such as sea urchins ( Figure below ), have spines that protect the organism. Sea cucumbers use these spines to help them move.