Meeting Abstract
21.5 Tuesday, Jan. 4 Comparative post-embryonic development of the cranial lateral line canal system in cichlid fishes: Temporal and spatial patterns DICKSON, JM*; WEBB, JF; University of Rhode Island; University of Rhode Island jdickson@my.uri.edu
Morphogenesis of the lateral line canals is a key feature of dermatocranial development in bony fishes. Of the four types of lateral line canals found among fishes, narrow and widened canals are thought to be functionally distinct. They are found among Lake Malawi cichlids providing an opportunity for interspecific developmental comparisons. Aulonocara hansbaenschi (widened canals) was reared at 80±1°F and sampled at 1-4 day intervals from hatch (5dpf) to >75 dpf and were either stained with DASPEI to localize neuromast receptor organs and then cleared and stained, or prepared histologically. All neuromasts in the mandibular (MD1-5), preopercular (PO1-6), supraorbital (SO1-5) and infraorbital (IO1-9) canals were identified and fish size at onset of canal development and at canal enclosure around individual neuromasts were recorded. Neuromasts are present at 6.5-8 mm SL, canal development commences at 8-9 mm SL (prior to yolk sac absorption). Canal segments around neuromasts MD3 and PO3/4 start to develop first (14 dpf, 8-9 mm SL) and then other segments develop rostrally and caudally. The SO canal develops unidirectionally, in caudo-rostral sequence, and is fully enclosed at >15 mm SL (>57 dpf); the IO canal develops rostro-caudally and is enclosed much later than the other canals. Enclosure of all canals is complete in juveniles 15-20 mm SL. Analysis of histological material reveals that the order of development in the MD and SO canals, but not the timing of complete canal enclosure, seems to be conserved in Aulonocara hansbaenschi, a congener (widened canals) and representatives of two other genera (narrow canals). Thus, spatial, but not temporal developmental patterns may be conserved among species that exhibit divergent adult morphologies. Supported by NSF grant IOS-0843307 to JFW.
