Meeting Abstract

S5-7   13:30 - 14:00  The water to land transition submerged: Multifunctional design of paired fins for use in swimming and in association with underwater structures. Hale, ME*; Galdston, SA; Arnold, BW; Song, CB; University of Chicago, Illinois; University of Chicago, Illinois; University of Colorado, Boulder; Univ of Chicago, Illinois mhale@uchicago.edu

Fins of fishes provide many examples of structures that are beautifully designed to power and control movement in water; however, some species use fins not only during swimming but also for substrate-associated behaviors where interactions with solid surfaces are key. Here we examine how the fins of fish with these multifunctional performance needs are structured and function. We both review previous research and add key new examples of specialized fins. In some species, different fins are used for the alternative functions. In other species, the same fin structure is used to accomplish both swimming and substrate-based behaviors. We further examine this second case of the multifunctional pectoral fin in bichirs and gobies but focus on a special intermediate fin of the hawkfishes. Along with a small number of other species, hawkfishes have pectoral fins with regionalized specializations for swimming and substrate-based behavior. In hawkfish the dorsal region of the fin is structured with flexible fin rays connected by the fin membrane. Ventrally rays are not interconnected beyond their base and are more robust. Routine swimming of the hawkfishes includes synchronous rhythmic rowing of the dorsal region with the ventral rays held closer to the body. Hawkfishes are most often found perching and moving on structures in their environments. During perching the ventral rays are in contact with the substrate and often splayed, maintaining the fish's posture. We will further discuss the neuromuscular underpinnings of the sub-functionalized fin. Approaches for accomplishing both fluid-based and solid substrate-based behavior with fins highlight alternative evolutionary directions for meeting functional demands of both land and water.