“…This is followed by a retraction of pelvic fins (Figures 5 & 6). Subsequently, as the body moves downwards, which occurs due to a forward (recovery stroke) swing of the pectoral fins, the pelvic fins expands almost instantaneously to absorb the impact force as described by Sayer (2005) and to Stefan adhere the fish body to its underlying substrate as described in our previous work in Wicaksono et al (2016) – see Supplemental Video Data for motion sequences of all fishes from several angles. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The black arrows identify the unchanged pelvic fin geometries while the blue arrows elucidate contraction of the pelvic fins. The picture of the locomotion sequence in Periophthalmus variabilis is reproduced and edited from our previous work by permission of Elsevier (from Wicaksono et al , 2016). Fig.…”
In this research, we compared the anatomy and biomechanics of two species of mudskipper vs an aquatic sandgoby in view of terrestrial locomotion. Of particular interest was the relationship (if any) of pectoral fin movement with pelvic fin movement. We show that the pelvic fins of the terrestrial mudskippers studied herein, are retractable and move antagonistically with the pectoral fins. The pelvic fin of the sandgoby studied here is contrarily non-retractable and drags on any underlying substrate that the sandgoby tries to crawl across. We find that the pelvic and pectoral fin muscles of all fish are separated, but that the pectoral fins of the mudskipper species have bulkier radial muscles than the sandgoby. By coupling a detailed morphological investigation of pectoral-pelvic fins musculature with finite element simulations, we find that unlike sandgobies, the mudskipper species are able to mechanically push the pelvic fins downward as pectoral fins retract. This allows for an instant movement of pelvic fins during the pectoral fin backward stroke and as such the pelvic fins stabilize mudskippers through Stefan attachment of their pelvic fins. This mechanism seems to be efficient and energy saving and we hypothesize that the piston-like action might benefit pelvic–pectoral fin antagonism by facilitating a mechanical down-thrust. Our research on the biomechanics of tree-climbing fish provides ideas and greater potential for the development of energetically more efficient systems of ambulation in biomimetic robots.
“…This is followed by a retraction of pelvic fins (Figures 5 & 6). Subsequently, as the body moves downwards, which occurs due to a forward (recovery stroke) swing of the pectoral fins, the pelvic fins expands almost instantaneously to absorb the impact force as described by Sayer (2005) and to Stefan adhere the fish body to its underlying substrate as described in our previous work in Wicaksono et al (2016) – see Supplemental Video Data for motion sequences of all fishes from several angles. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The black arrows identify the unchanged pelvic fin geometries while the blue arrows elucidate contraction of the pelvic fins. The picture of the locomotion sequence in Periophthalmus variabilis is reproduced and edited from our previous work by permission of Elsevier (from Wicaksono et al , 2016). Fig.…”
In this research, we compared the anatomy and biomechanics of two species of mudskipper vs an aquatic sandgoby in view of terrestrial locomotion. Of particular interest was the relationship (if any) of pectoral fin movement with pelvic fin movement. We show that the pelvic fins of the terrestrial mudskippers studied herein, are retractable and move antagonistically with the pectoral fins. The pelvic fin of the sandgoby studied here is contrarily non-retractable and drags on any underlying substrate that the sandgoby tries to crawl across. We find that the pelvic and pectoral fin muscles of all fish are separated, but that the pectoral fins of the mudskipper species have bulkier radial muscles than the sandgoby. By coupling a detailed morphological investigation of pectoral-pelvic fins musculature with finite element simulations, we find that unlike sandgobies, the mudskipper species are able to mechanically push the pelvic fins downward as pectoral fins retract. This allows for an instant movement of pelvic fins during the pectoral fin backward stroke and as such the pelvic fins stabilize mudskippers through Stefan attachment of their pelvic fins. This mechanism seems to be efficient and energy saving and we hypothesize that the piston-like action might benefit pelvic–pectoral fin antagonism by facilitating a mechanical down-thrust. Our research on the biomechanics of tree-climbing fish provides ideas and greater potential for the development of energetically more efficient systems of ambulation in biomimetic robots.
“…These modifications are hypothesized to increase the flexibility and strength of the rays to assist in station‐holding on the bottom in flow (Lundberg & Marsh, ). A study of tree‐climbing mudskippers found that their ability to adhere to vertical surfaces improved with more flexible pelvic‐fin rays (Wicaksono et al, ). Our own work on pectoral‐fin rays in benthic longhorn sculpin has demonstrated that the location and magnitude of the curvature of their fin rays is affected by both the ray's cross‐sectional shape and the proportion of the ray that is unsegmented versus segmented (Figure ) (Taft & Taft, ; Taft et al ).…”
Although the ray-finned fishes are named for their bony, segmented lepidotrichia (fin rays), we are only beginning to understand the morphological and functional diversity of this key vertebrate structure. Fin rays support the fin web, and their material properties help define the function of the entire fin. Many earlier studies of fin ray morphology and function have focused on isolated rays, or on rays from only one or two fins. At the same time, relatively little is known about how different preservation techniques affect the material properties of many vertebrate structures, including fin rays. Here, we use three-point bending tests to examine intra- and inter-fin variation in the flexural stiffness of fin rays from yellow perch, Perca flavescens. We sampled fin rays from individuals that were assigned to one of three preservation treatments: fresh, frozen, and preserved with formalin. The flexural stiffness of the fin rays varied within and among fins. Pelvic-fin rays were the stiffest, and pectoral fin rays the least stiff. The fin rays of the dorsal, anal, and caudal fins all had similar stiffness values, which were intermediate relative to those from the paired fins. The flexural stiffness of the fin rays was higher in rays that were at the leading edge of the fin. This variation in flexural stiffness was associated with variation in joint density and the relative length of the unsegmented proximal base of the fin rays. There was no significant difference in flexural stiffness between fresh and frozen specimens. In specimens preserved with formalin, there is a small but significant effect on stiffness in smaller fin rays.
“…These characteristics are supported by the existence of pectoral fins that have been evolved into sturdy legs and can be used to walk in mud (Al-behbehani and Ebrahim, 2010). The base of the pectoral fins is sturdy enough that can be bent and serve as arms for creeping, crawling, and leaping (Wicaksono et al, 2016). According to Wicaksono et al (2020), Periophthalmus variabilis has unusual climbing and jumping ability, it can cross the water surface by leaping and can change its direction while on the water surface.…”
Section: The Biology Uniqueness Of Mudskippers (Teleostei: Gobiidae: mentioning
ecosystem functions. The main effects of long-term heavy metal pollution include biodiversity and habitat degradation. These pollutants can disrupt living organisms at the molecular, cellular, and physiological levels, resulting in adverse effects at the population and community levels (Lionetto et al., 2019). Heavy metal pollution mostly comes from anthropogenic practices as a result of industrialization, farming operation, and urban growth (AnvariFar et al., 2018). Heavy metals that often pollute estuaries are Cu, Zn, Fe, Pb, Cd, Hg, and Ag (Marques et al., 2019). However, society often overlooks the health effects of heavy metals and our overall knowledge about the biological effects of heavy metals on estuary ecosystems is minimal. Accordingly, establishing a biomonitoring program using biomarkers as an early identification tool is mandatory for preventing the harmful effects of heavy metal pollutants on the estuary ecosystem. The purpose of the biomonitoring program is to measure the environmental quality through the use of living organisms on a regular and systematic basis or through their normal responses as markers in the environment (
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