Meeting Abstract

P2.85  Jan. 5  Form and Function of Stingray Mechanosensory and Electrosensory Systems (Elasmobranchii: Batoidea) JORDAN, L.K.; Univ. of California, Los Angeles ljordan@ucla.edu

Elasmobranch fishes (sharks, skates, and rays) demonstrate remarkable sensory capabilities which are used for a variety of purposes including locating and capturing prey. This study compares the sensory anatomy to detection capabilities of the mechanosensory lateral line system and the electrosensory system in the benthic feeding round stingray, Urobatis halleri, and bat ray, Myliobatis californica. These systems allow elasmobranchs to locate prey through detecting water movements and electrical fields respectively. Predictions based on detailed maps of the sensory anatomy were tested in behavioral detection experiments. U. halleri feeds primarily on small epifaunal benthic invertebrate prey and the lateral line of this species shows a high proportion of ventral non-pored canals while the electrosensory pores are highly concentrated around the mouth. M. californica feeds primarily on infaunal benthic invertebrates as well as some more mobile invertebrates and fishes. The lateral line system in this species is highly branched with a large number of pores per branch. The electrosensory system shows a high pore number and is highly concentrated anteriorly. In M. californica both systems have dramatic lateral extension toward the wing tips on the anterior edge of the pectoral fins providing a larger lateral search area. Responses of both species to water jets at 10 cm/s and weak electrical fields are compared. Response thresholds to electrical fields were comparable to those observed for sharks with minimum responses below 1 nV/cm. Implications of these results are discussed within the context of the ecology of these species.