The overall shape of a starfish can provide useful characters – whether the arms are long and the central disk area small or whether the disk is large. The form of the skeleton is a very important character. The skeleton is a series of connected plated which often bear spines, granules or knobs. The form and arrangement of theses plates is important. The form of the tube feet, whether pointed or suckered is used to distinguish group of starfish from the rest. In the study area species of Astropecten can sometimes be encountered off-shore superficially resembling Archaster but differing in having pointed tube feet.
Taxonomic name: