Meeting Abstract

P2.85  Saturday, Jan. 5  The curious shapes of sea urchin larvae: A comparative investigation into a putative olfactory structure MACNEIL, K/E A*; BISHOP, C/D; St. Francis Xaviery University, Antigonish NS; St. Francis Xaviery University, Antigonish NS x2007tev@stfx.ca

Sea urchin planktotrophic larvae have evolved highly elaborate body shapes to increase the surface area of the body and thus the length of the ciliary band, their feeding and locomotory organ. One such elaborated structure is the adoral lobe (ADL), a newly described putative olfactory structure on the ventral surface of Lytechinus variegatus larvae. The ADL is composed of ciliary band and the associated epithelium, which are folded into a “U “shape. At the base of the “U” shape NOS-defined neurons (NDNs) differentiate and project axons to the pre-oral neuropile around the time of juvenile rudiment formation. I am interested in the relationship between the number and distribution of neurons and the morphology of the surrounding epithelium. Are there functional reasons for this intriguing structural arrangement? There is considerable interspecific variation in the presence (some feeding larvae do not have one) and shape of this structure among sea urchin larvae, the significance of which remains untested. Therefore my near term goal is to establish a method to conduct a comparative morphologic analysis of the ADL. Thereafter, I will test for the presence and distribution of neurons in this region of selected larvae. Using the comparative method, I will test my hypothesis that there is a function reason for the specific placement of NDNs within the ADL that predicts covariance between the presence of NDNs and an ADL.