Meeting Abstract
P2.110 Monday, Jan. 5 Preliminary observations on the development of the little skate, Leucoraja erinacea, with reference to the mechanosensory lateral line system. HACISKI, S. Insley*; WEBB, Jacqueline F.; University of Rhode Island haciski@mail.uri.edu
The development of the elasmobranch lateral line system has been studied in only a few species, with papers published just twice in the past 100 or so years, and has not been studied in detail in batoids. Here, the development of the little skate, Leucoraja erinacea, is described as a basis for the study of the development of its lateral line system. Adult skates, which readily lay eggs in captivity, were maintained in tanks with recirculating seawater at 15-16C. Eggs laid in Dec. 2007 were candled and embryos were fixed in 10% formalin in PBS over several months. Another eight eggs, laid on known dates (Jan.-May 2008), were sampled periodically to begin to generate a developmental series for more detailed analysis. Results showed that in 38 individuals (49-91 mm TL) both disc width (DW) and tail length (TL) scale positively with increasing total length (TL). Paired somites and tail bud were visible at 4.5 mm TL (14 days post-deposition [dpd]). Pharyngeal arches were visible at 6 mm TL (18 dpd). External gills were visible at 25 mm TL and were resorbed at 73 mm TL. Early stages of the hyomandibular and scapular lateral line canals were visible in a 50 mm TL embryo. The pectoral fins were partially fused to the rostrum in a 42 mm TL embryo and remain caudal to the mouth until fusion was complete at 50 mm TL. A cleared and stained hatchling (93 mm TL, day of hatch) revealed what appears to be a complete dorsal and ventral lateral line canal system indicating that canal morphogenesis occurs prior to hatching. Further details of lateral line development will be studied using histological analysis and SEM in order to determine the timing of neuromast differentiation, ontogenetic trends in neuromast size and shape, and the timing and pattern of lateral line canal morphogenesis.
