For more information than you'll ever want get a copy of the Peterson field guide to the Atlantic Seashore and look up Errant (Moving/swimming) Polychaetes. As mentioned there are many types with my favorite being the Dumerils clam worm. Most swarms involve reproductive members utilizing external fertilization but the Dumerils have aquired a 'unique' method. Quoting Petersons "The female siezes the male's tail end in jaws injesting sperm through the mouth causing the internal organs of the female (thinned and weakend by entering the reporductive stage) to allow passage through and directly to the eggs, which, now fertilized burst through the body cavity and into the sea. Presumably both male and female die after mating". And you thought being married with kids was tough
In addition, the worms actually manufacture a breeding part which 'snaps off' the main worm to go spawn. Imagine the possibilities
