Sea Urchin Skeletal System
The sea urchin builds spicules, their bones or sharp crystallines, that encompasses its endoskeleton, the sea urchin makes itself its skeleton during its larval stage.
In other echinoderms, the endoskeleton is put together with another layer of muscle that allows the animal to move its arms or other body parts. Sea urchins are unable to move in this way.
In other echinoderms, the endoskeleton is put together with another layer of muscle that allows the animal to move its arms or other body parts. Sea urchins are unable to move in this way.