Regeneration in worm larvae, Family Spionidae

Abstract

Metazoan lineages exhibit a wide range of regenerative capabilities in their adult forms, however, less is known about larval regeneration. Our study evaluated whether larvae of Spionid worms were capable of regeneration. We chose Spionids due to their abundance in the near-shore waters of Friday Harbor Laboratories (WA) and because information is available on their regenerative abilities as adults. We sought to answer the following questions: (1) do larvae survive after bisection? (2) do larvae exhibit wound healing and regeneration of the lost tissues at cut regions of the anterior and posterior body segments? To do this, we collected 78 larval Spionid worms, photographed each one and grouped them into tentative larval stage and species groups. We then bisected and monitored worms for survival and signs of regeneration. Overall, anterior body parts had higher survival than posterior body parts and regeneration was observed in both worm sections. However, we were unable to detect patterns in regeneration due to uneven sampling size per group. In order to better understand the difference between groups, surviving larvae will be barcoded to determine actual species. Future experiments should be extended to observe until complete regeneration occurs. Studies in regeneration, such as this one, are important as it can reveal evolutionary relationships among polychaetes, further our understanding of developmental processes in marine worm larvae, and understand survival under sublethal predation.