Meeting Abstract

P2.83  Sunday, Jan. 5 15:30  Development of the Cranial Lateral Line Canal Pores in Two Species of Cichlid Fishes with Functionally Distinct Canal Morphologies CARTER, L*; WEBB, JF; University of Rhode Island; University of Rhode Island carterl@my.uri.edu

The cranial lateral line system (LL) is composed of a series of bony, pored canals that are integrated within a conserved subset of dermatocranial bones. Neuromast receptor organs are located in the canals between positions of adjacent canal pores (bony pores and pores in the overlying epithelium), which link the fluid within the canals to the fluid of the external environment. Pore size and inter-pore distance are important for predicting the functional properties of the canal, and thus the way in which canal neuromasts respond to external water flows. It was hypothesized that the size of these pores decreases and the number of pores decreases as a fish grows. This hypothesis was tested using two species of Lake Malawi cichlids that are characterized by differences in pore size – Tramitichromis sp., which has small pores and narrow canals, and Aulonocara stuartgranti, which has larger pores and widened canals. Pore length, width, and cross-sectional area (approximated) were analyzed in the supraorbital and mandibular canals of larvae and juveniles from 6.0-19.5 mm SL using histological material, juveniles visualized using SEM, and adults stained with methylene blue and then cleared and stained for bone. Preliminary data show that there are complex relationships between the timing of formation and the size and number of bony and epithelial pores through ontogeny in both species. In juveniles, bony pores are larger than epithelial pores especially in Aulonocara. The complexity of ontogenetic trends in pore number and morphology predict unappreciated variation in LL function through ontogeny. Supported by NSF grant IOS-0843307 to JFW.