|Bristle worms, or Polychaeta, (= many bristles) are marine organisms related to the common earthworm. They have segmented bodies and very distinct bristles that are implanted in each segment.|
Many people will not be aware of their importance because they are almost exclusively marine creatures. They are extremely abundant. Mud dwelling forms are the main food of many shore birds.
Although most Polychaetes are burrowers or live crawling around the bottom of the sea their larvae are mostly pelagic (floating in the plankton).
This image shows that Polychaetes are not simple organisms. They have a well developed nervous system. In this larva the nerves can be seen in the image as black branching structures.