JACKSON, J.L.; LINDSAY, S.M.: A comparison of anterior regeneration between Dipolydora quadrilobata and Pygospio elegans

Spionid polychaetes display a variety of reproductive strategies, from asexual to sexual reproduction of both planktotrophic and lecithotrophic larvae. Like other polychaetes, spionids often lose anterior body parts to browsing predators; they regenerate this tissue over time. This study compared rates of anterior regeneration in 2 spionid polychaete species with different reproductive modes: Dipolydora quadrilobata (sexual) and Pygospio elegans (asexual architomy). We tested the hypothesis that anterior regeneration would be faster in the asexually reproducing species. Treatments manipulated various stages of injury: an intact control, loss of the palps, loss of the anterior through the first setiger, and loss of the anterior through the fifth setiger. Surgeries were performed with watchmakers forceps and a micro-scalpel. Worms were maintained in individual 5ml petri dishes filled with seawater and a light dusting of 0.5mm sieved surface sediment to cover the bottom of the dish. Seawater was changed daily and sediment was changed every time the worms were filmed. Using a camera mounted on a dissecting scope, worms were video taped for 2 minutes every other day for 6 days and then every day until they regenerated functional anteriors (11-16 days). Worms of both species successfully regenerated anterior tissue. Growth was significantly faster in the asexually reproducing P. elegans. Examination of nerve regeneration is in progress. Partly funded by NSF grant OCE 9973327 to SML.