sentences:  In most species, this larva has 12 elongated arms lined with bands of cilia that capture food particles and transport them to the mouth.In a few species, the blastula contains supplies of nutrient yolk and lacks arms, since it has no need to feed.Several months are needed for the larva to complete its development, the change into the adult form beginning with the formation of test plates in a juvenile rudiment which develops on the left side of the larva, its axis being perpendicular to that of the larva.