In undulating rays, the broad, flexible pectoral fins allow for substantial variation in waveform as the propulsive wave propagates across the fin surface. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The disc portion of their bodies is used to increase their efficiency during the gliding portion of their swimming.[13]. Frequency (f) was determined as the number of wave cycles per second at mid-disc. Curvature varies across the mediolateral axis, increasing dramatically near the distal margin. The cartilaginous fishes are distinguished fro… Walking in skates resembles the ancestral tetrapod sprawling loco-motion seen in many salamanders and lizards. See more. Dorsal view of freshwater stingray Potamotrygon orbignyi (anterior at top); purple circles indicate the locations of the 31 points digitized on the dorsal surface of the right pectoral fin. However, in approximately one-third of the sequences the fin retained negative curvature for over 75% of the wave cycle. was measured from the most anterior point on the stingray snout to the posterior margin of the pectoral fin disc, and is equivalent to chord length. Axial locomotion occurs when the animal modifies its body shape to achieve motion. 3). In appendicular locomotion, various appendages such as legs, wings, and flippers interact with the environment by pushing or flapping to produce the propulsive force. In stingrays, retaining a concave-down fin shape is also likely to have hydrodynamic significance, as it will affect flow passing beneath and beside the fin. (A) Amplitude variation across the pectoral fin surface; warmer colors represent greater magnitudes. Other animals explore both the aquatic and aerial realm more extensively. Cycles are divided into upstrokes (top row), defined as the portion of the wave cycle where the fin moves from trough to crest, and downstrokes (bottom row), defined from crest to trough. Models of knifefish (Curet et al., 2011), undulatory rays and ray-like fins (Low, 2006; Clark and Smits, 2006) may be based on different organisms, but they share the same underlying principle: locomotion is controlled by a single undulating surface, with modulations of the wave function producing steady swimming, acceleration or more complex maneuvers. The eyes and spiraclesare located on the upper surface of the head and the gill slits are on the underside of the body. LOCOMOTOR MOVEMENTS • This are done by moving the body from one place to another. We therefore expect similar individual variation in P. orbignyi, with swimming speed driven by either the frequency or amplitude of the pectoral wave. crest or trough) to travel that distance. There has been little study into their swimming characteristics but it can be assumed from their morphological similarity to sharks that they rely primarily on body caudal fin swimming and the pectoral fins do not generate thrust. increased tailbeat frequency) while amplitude remains constant (Bainbridge, 1958; Drucker and Jensen, 1996). Most importantly, though, the amplitude pattern presented for T. lymma highlights the limitations of 2-D analyses when interpreting 3-D waveforms. Our analysis reveals that frequency and wavespeed – the two main drivers of swimming speed in P. orbignyi – are accurately represented by mid-disc values, but that major features of pectoral fin undulation can only be described when the fin is considered as a 3-D undulating surface. We thank E. M. Standen, J. Lim, N. Danos and B. Flammang-Lockyer for helpful conversations during both the data collection and analysis phases of this work, as well as A. Stubbs for assistance during experiments. Different parts of the disc are considerably more flexible than others and some parts are designed to passively deform. (A) Magnitude of positive (light blue/red) and negative (deep blue/red) mediolateral fin curvature at both swimming speeds, with no significant differences by curvature sign or speed (P>0.05). Batoids that utilize mobuliform swimming can be identified by their high aspect ratios, thicker pectoral fins that taper to a point and a lateral profile that resembles a hydrofoil. 2.1 SUPPORT ANDLOCOMOTION IN HUMANSAND ANIMALS 3. values within the margin of experimental measurements, as demonstrated by the amplitude measured at non-oscillating midline points) (Fig. Of the four orders of Batoidae this holds truest for the Myliobatiformes (rays) and the Rajiformes (skates). Spanwise amplitude variation along the mediolateral axis at positions indicated on the stingray image. They tend to be incredibly efficient swimmers many pelagic ray species and even some benthic species undertake very long yearly migrations. Increases in the amplitude of propulsive motions, whether a trout's tailbeats or a stingray's undulations, increase projected area and therefore increase drag; a higher swimming speed resulting from increased amplitude would only heighten the drag effect. Given the size of the fin, a maximum amplitude of less than 2 cm seems small, but still represents a significant fraction of disc width, and is in the range of standardized mid-disc amplitudes found for other batoids (Rosenberger, 2001). Rosenberger (Rosenberger, 2001) identified a continuum of batoid locomotion between oscillation and undulation, with species' position between the two extremes defined by the number of waves present on the pectoral fin at one time; undulators have more than one wave, oscillators less than one. Stingrays were filmed while swimming in a calibrated, variable-speed flow tank (see Tytell and Lauder, 2004), heated to 27±1°C, at a Reynolds number of approximately 10,000. 20-03). I. Kinematic effects of swimming speed and body size, A robotic fish caudal fin: effects of stiffness and motor program on locomotor performance, The relation between structure and bending properties of teleost fin rays, Undulatory locomotion in elongate aquatic vertebrates: anguilliform swimming since Sir James Gray, Studies in animal locomotion. They are slower than mobuliform swimmers but they are some of the most metabolically efficient elasmobranch swimmers at slow speeds.[9]. Undulatory swimmers propel themselves by passing a wave of bending along a flexible fin or body surface; modulations of the wave produce changes in swimming speed or instigate maneuvers. Future studies calculating this value should consider the path of wave travel when selecting a method of standardization. Unlike other fishes, which typically interact with the fluid environment via multiple fins, undulating rays modulate a single control surface, the pectoral disc, to perform pelagic locomotion, maneuvering and other behaviors. Stingrays can maintain extreme lateral curvature of the distal fin margin in opposition to induced hydrodynamic loads, ‘cupping’ the edge of the pectoral fin into the flow, with potential implications for drag reduction. This yields higher body angles than would be calculated from the flat ventral surface, as stingray body depth decreases from head to tail; a sagittal cross-section through the midline would resemble an airfoil, with a flat ventral surface and cambered dorsal surface. The two other orders: Rhinopristiformes and Torpediniformes exhibit a greater degree of body caudal fin swimming. Rajiform locomotion in fishes is dominated by distinctive undulations of expanded pectoral fins. The asymptotic amplitude pattern we observe in P. orbignyi would reduce projected area, even without the posterior decrease seen in T. lymma: as amplitude nears the asymptote, projected area does not increase further. In addition to the anteroposterior bending that accompanies the propulsive wave, stingray fins show mediolateral curvature, with a maximum of 0.06±0.02 mm−1 in both positive (concave up) and negative (concave down) directions (Fig. Chordwise amplitude variation along the anteroposterior axis at positions indicated on the stingray image. 9B). For children, practicing specific skills helps to build coordination and balance. Mean values of major kinematic variables at each swimming speed, 1.5 DL s−1 (blue) and 2.5 DL s−1 (red). Fish when it comes to maneuverability of cilia extends from head to tail active interactions the! Disturbance when they move virtually all behaviors using a single broad surface: the distinctive, expanded pectoral fins propel. 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