Ontologically, however, the two bands of bipinnaria do not appear to arise from the division of a single band.
bipinnaria or Branchiolaria: The larval stage of starfishes.
The commonest and most thoroughly investigated form of Asteroid larva is a free-swimming form known as bipinnaria.
Thus the larv of the starfishes were called bipinnaria, the larv of the sea-urchins Pluteus, and so on.
The egg becomes a sort of infusoria, the infusoria becomes a bipinnaria, and this produces the Asterias.
The bands of cilia have the same general form as in bipinnaria.
The presence of two rings instead of one distinguishes the bipinnaria from the Auricularia.