noun, plural am·bu·lac·ra [am-byuh–lak-ruh, –ley-kruh] /ˌæm byəˈlæk rə, -ˈleɪ krə/.
- one of the radial areas in an echinoderm, as the sea urchin, bearing the tube feet by which the creature moves.
noun plural -ra (-rə)
- any of five radial bands on the ventral surface of echinoderms, such as the starfish and sea urchin, on which the tube feet are situated