Cornett, Anthony D.

Sharks possess an electrosensory system which allows the detection of
electric fields . How this system varies among related taxa and among species
inhabiting different environments remains unexplored. Electroreceptor number
was quantified for representative species of related taxa (genera, families, orders)
from different environments (pelagic, coastal, deepwater) and taxa from similar
environments to determine potential phylogenetic constraint or evolutionary
convergence. Coastal open water sharks possess the greatest number of
electroreceptors; deepwater sharks the least. Pelagic and coastal benthic sharks
retain comparable electrosensory pore numbers despite inhabiting vastly different
environments. Electrosensory pores were primarily located in ventral
distributions, except among coastal open water sharks which possess roughly
even distributions around the head. Among related species and genera, pore
numbers and distribution are comparable, with greater variation among higher
taxa. Results implicate evolutionary convergence as the primary influence in
electroreceptor development, while phylogenetic constraint establishes similar
base values for number and distribution.