Sexual and Ontogenetic Dimorphisms in the Anterior Lateral Line Nerve of the Yellow Singray, Urobatis jamaicensis

To fully understand the function of the elasmobranch
electrosensory system it is necessary to examine
electrosensory nerves extending from the ampullae
of Lorenzini to the central nervous system. Studies
detailing the composition of sensory axons are rare,
but they have shown that ontogenetic and sexual
dimorphism exists in the anterior lateral line nerve
(ALLN) of numerous species. This study obtained a
count of the number of axons comprising the ALLN in
male vs. female and adult vs. juvenile yellow stingrays
(Urobatis jamaicensis). We hypothesized that
males have more axons than females, and that the
number of axons is ontogenetically constant. We
expect males to have 30% more axons in their ALLN,
and that the number of axons is ontogenetically constant
for both sexes. This study will provide unique
data about the electrosensory nerves of Yellow
stingrays that can be used in future studies to make
comparisons between other species.