It indicates the frequency of the swirl and the distance between them. Pell, and S.A. Wainwright. Figure 6 illustrates the basic principle of DPIV as used in our experiments visualizing flow in the wake of the caudal fin. The HL muscle originates from the ventrolateral surface of the caudal skeleton and passes posterodorsally to make four tendinous insertions on the first four fin rays. 10). 15. These methods are then applied to the function of the caudal fin during steady swimming in fishes with heterocercal and homocercal morphologies: chondrichthyians (leopard sharks) and ray-fined fishes (sturgeon and bluegill sunfish). The assumption of horizontal reaction forces based on morphological symmetry is certainly incorrect, as the homocercal tail is generating lift forces even during horizontal locomotion. This paper has three aims. Dickson, and G.V. The technique of DPIV (digital particle image velocimetry) provides a means of quantifying fluid flow and of calculating forces exerted by fishes swimming in vivo. The interradialis and flexor muscles within the tail show no activity at this speed. 2) that is found within all major clades of ray-finned fishes. 3). Quantitative flow visualization in the wake of bluegill swimming in a flow tank at 1.6 lengths/sec (Fig. Such views appear to show that the ventral lobe of the tail leads the dorsal for portions of the tail beat and that the tail appears to be oriented in a manner that might direct a reactive force ventrally through the center of mass. Does Jerry Seinfeld have Parkinson's disease? Anatomically, these muscles consist of dorsal and ventral flexor muscles (which often have deep and superficial components), the carinal muscles that connect the most dorsal and ventral skeletal elements of the tail to the dorsal and anal fins, and interradialis muscles (Fig. In homocercal tails, the vertebral column typically terminates near the base of the skeletal elements supporting the tail (hypural bones in teleosts), and although the internal caudal skeleton is not completely dorsoventrally symmetrical, the dorsal and ventral lobes of the tail are nearly equivalent in area and composition. 1. Broad evolutionary patterns of caudal fin structure have now been relatively well documented in fishes, and the internal anatomy of the caudal fin is a common source of characters for phylogenetic analysis (Patterson, 1968, 1973; Schultze and Arratia, 1986, 1988; Arratia, 1991). In contrast, the alternative model predicts that the XZ angle will be less than 90° with the expectation that water influenced by motion of the tail will be directed posterodorsally and thus create a reaction force directed slightly ventrally through the center of mass. Previous kinematic data have supported the classical theory which proposes that the beating of the heterocercal caudal fin during steady horizontal locomotion pushes posteroventrally on the water, generating a reactive force directed anterodorsally and causing rotation around the … The experimental data described above on the function of heterocercal and homocercal and caudal fins suggests that a reevaluation of the classical models of both caudal fin types is needed. 1, 2) is in need of reevaluation in the light of new functional data. One of the most prominent characteristics of early vertebrate fossils is the elongate tail bearing fin rays (Fig. Preparation of this manuscript was supported by NSF grant IBN 9807012 to GVL. Wolfgang, M.J., J.M. Facey. Positive Z values indicate a vector pointing to the right and negative values a vector pointing to the left. Graphs of three-dimensional orientations of sturgeon tail triangles (Fig. But the hypochordal longitudinalis (HL) muscle possesses a fiber axis at an appreciable angle to the horizontal (Fig. Small reflective particles are placed in the water and light from a laser is focused into a light sheet which reflects off of individual particles and is imaged by high-speed video. The changing orientation of sturgeon tail triangles, the oscillatory pattern of the Y movement vector component, and the orientation of vortices shed behind the tail is not consistent with the classical hypothesis of heterocercal tail function for sturgeon. Previous work with Lara Ferry-Graham was critical in understanding the function of the shark tail. Finally, the significance of the diversity of tail designs in early vertebrates and major evolutionary patterns to tail morphology (Figs. But the vortex rings generated by the sturgeon tail are oriented with an oblique axis and a central jet of fluid directed posteroventrally. Figure 8 shows six representative video frames, each illustrating a simultaneous lateral and posterior view of the tail. Heterocercal tail kinematics in the sturgeon, Acipenser transmontanus. Bemis, W.E., E.K. These muscles are approximately symmetrically arranged about the horizontal axis and would seem to have generally symmetrical effects on dorsal and ventral tail lobes. One source of error in two-dimensional kinematic analyses. Red fibers in myotomes of the caudal peduncle show light rhythmic bursting activity typical of locomotion at this speed, just above the transition from pectoral to caudal propulsion (Gibb et al., 1994). While quantifying the three-dimensional motion of the caudal fin is one critical component of understanding caudal fin function, it is also necessary to evaluate the impact that movement of the fin has on the fluid. These experimental data also indicate that the function of homocercal tails is considerably more complex than previously appreciated. The skeleton of the fish is made of either cartilage (cartilaginous fishes) or bone (bony fishes). Lauder and Jayne (1996) showed that angles of fin surfaces estimated from two-dimensional analyses can be in error by as much as 83° from the correct three-dimensional angle (and further details about 3D angle calculations can be found in that paper). Heterocercal tail kinematics in the leopard shark, Triakis semifasciata swimming steadily at 1.2 lengths/sec. However, analysis of steady swimming in chub mackerel (Scomber japonicus) (Gibb et al., 1999) reveals a similar pattern of asymmetry with the dorsal lobe undergoing a 15% greater Z excursion than the ventral lobe.
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