Meeting Abstract

P1.55  Sunday, Jan. 4  Four-eyed fish (Anableps anableps)use the same jaw-opening movements to produce a distinct prey-capture behavior across environments KUSHNER, S.A*; GIBB, A.C; ARENA, A; FERRY-GRAHAM, L.A; Mansfield University of Pennsylvania; Northern Arizona University; Northern Arizona University; Moss Landing Marine Laboratory kushners@mounties.mansfield.edu

Four-eyed fish, Anableps anableps, are native to northern South America and inhabit mangrove swamps. They swim at the water’s surface so that their eye is bisected by the air-water interface, which allows a simultaneous view of both aerial and aquatic environments. A. anableps feed both in the water on aquatic organisms, and out of water on intertidal, terrestrial and even low-flying aerial organisms. In the laboratory, A. anableps were offered prey items (crickets) held on forceps both above (aerial) and below the surface of the water (aquatic). Using high-speed digital-imaging, we recorded and quantified five displacement variables and five timing variables associated with the head and jaw movements during the mouth-opening phase of prey capture in both environments (e.g. maximum gape, time to maximum jaw depression, etc.). Surprisingly, the relative timing and magnitude of these movements were statistically indistinguishable across environments. However, the time between mouth opening and prey contact was longer and strike velocity was more rapid when A. anableps were feeding on prey held above the surface. These results suggest that a single set of cranial movements is used to produce mouth opening in both environments, but the predator is physically closer to the prey-item when these movements occur underwater. The ram-suction-index (RSI) indicates that the movements of the neurocranium and jaws produce effective suction during aquatic feedings, but the same movements result in a ram-based prey capture during aerial feedings.