Meeting Abstract

P2.126  Jan. 5  Worms as architects – building a better sense of the interior design of tubes MERZ, R. A.; Swarthmore College rmerz1@swarthmore.edu

When a polychaete moves from one end of its tube to the other, braces against the tube wall during peristaltic pumping, or anchors within its tube to avoid removal by predators or maintain its position while living a life in moving fluids it controls the traction that exists between its body and the tube wall. Polychaetes manage this using a variety of anatomical features primarily associated with their parapodia. What, if any, are the correlates between the scale and shape of parapodial structures and the macroscopic and microscopic features of the inner surfaces of worm tubes? Do these two sets of features work together as one of life’s devices? To examine this comparative biomechanics question I used light and scanning electron microscopy to view and quantify structures on the bodies and tubes of 20 species of polychaetes representing 11 families and six orders. In many species there are macroscopic bumps or ridges that protrude somewhat into the lumen of the tube, which could provide some sort of “purchase”. In some cases these features are the result of sediment (e.g. sand grains in maldanid or sabellarid tubes) or organic particles (e.g. plant or algal bits in ampharetid or nereidid tubes) that are incorporated into the tube structure, in other cases (e.g. chaetopterids and serpulids) the worms themselves secrete the material that forms ridges. On a finer scale there are orderly micro-ridges (owenids) and “fabrics” of mucus-based threads that provide bas-relief on the same scale (microns) as ornamentation of individual chaetae. The fine structures of tubes in conjunction with the morphologies of the worms that build them provide new ways to evaluate both how worms live within their tubes and how different lineages of worms have evolved.