Meeting Abstract
68.1 Tuesday, Jan. 6 Is there functional convergence among ray-finned fishes with a crocodilian-like morphology? Feeding behavior of the small piscivore Belonesox belizanus GIBB, A*; PACE, C; FERRY-GRAHAM, L; ARENA, A; PORTER WOLFE, H; Northern Arizona University; Northern Arizona University; Moss Landing Marine Laboratory; Northern Arizona University; University of South Florida alice.gibb@nau.edu
The pike killifish Belonesox belizanus (Cyprinodontiformes: Poeciliidae) is an extremely small piscivore with highly-elongate anterior jaws, a reduced ligamentous connection between the upper and lower jaws, and numerous unicuspid teeth. Due to its superficial similarity with crocodilians, we term these cranial modifications a "crocodilian" morphology. We quantify the strike and prey-capture behavior of Belonesox and compare these parameters with published data for other ray-finned fishes (Actinopterygii) that also feed on fish-prey and possess this crocodilian morphology, including Lepisosteus (gar), Strongylura (needlefish), and Sphyraena (barracuda). Belonesox show convergence in aspects of the strike and prey-capture behavior with other piscivores; for example, many (but not all) of these piscivores use an S-start to produce a rapid forward attack on the prey. However, each piscivore employs a distinct combination of axial and cranial movements to lunge toward fish-prey and entrap them within the jaws. Thus, we concur with previous researchers that morphological convergence does not dictate functional convergence in prey capture behavior. However, based upon the literature, we posit that the crocodilian morphology may provide specific performance advantages for physically entrapping and handling large fish-prey; unfortunately, these hypothesized advantages remain to be tested in a phylogenetic context. Finally, the presence of very small juvenile fishes (the offspring of other livebearers) in the same habitat as Belonesox may allow this species to exploit fish as their primary prey items immediately after birth, thus allowing them to become some of the smallest known vertebrate piscivores.
