Ophiura albida (Echinodermata, Ophiuroida, Ophiuroidae), late pluteus larva, width 700 µm, Helgoland 07.2013. 0:40 min. Development of Ophiuroida is characterized by the ophiopluteus larva with mainly four and up to six pairs of arms, stabilized by delicate calcite rods. Anchoring body rods and additional transvers rods of a species-specific arrangement connect these skeletal elements. From the coelomic cavities the five pouches of the hydrocoel on the left side are prominent. Ciliary bands around the mouth and on the arms propel the plutei through the water. Video can be used for teaching.