Remarkably, the pluteus of some ophiuroids develops, undergoes metamorphosis, and eventually the juvenile brittle star settles to the substrate. The remaining parts of the larvae are then released, swim back up into the water column and then regenerate, ultimately forming a secondary pluteus which also undergoes metamorphosis and settles forming another juvenile brittle star. Some deep-sea species, especially in the genus Ophiura , exist in very high density aggregations. Ophiuroids have used their ability to autonomize in many ways. Some ophiuroids reproduce asexually.
Autonomy is a great way to escape being eaten by a predator.
Usually just an arm is sacrificed to the predator while the brittlestar escapes. Notice that in this photo, and in the one provided by Samuel Dupont , that the bioluminescent regions on the animal are the arms. The central region is dark. The arms are replaceable, but damage to the disk of the animal can be more serious. Samuel DuPont has created an online presentation for a recent conference he attended.