Aquatic locomotion

About: Aquatic locomotion is a research topic. Over the lifetime, 69 publications have been published within this topic receiving 3796 citations. The topic is also known as: swim & active swimming.

Review of fish swimming modes for aquatic locomotion

Abstract: Several physico-mechanical designs evolved in fish are currently inspiring robotic devices for propulsion and maneuvering purposes in underwater vehicles. Considering the potential benefits involved, this paper presents an overview of the swimming mechanisms employed by fish. The motivation is to provide a relevant and useful introduction to the existing literature for engineers with an interest in the emerging area of aquatic biomechanisms. The fish swimming types are presented, following the well-established classification scheme and nomenclature originally proposed by Breder. Fish swim either by body and/or caudal fin (BCF) movements or using median and/or paired fin (MPF) propulsion. The latter is generally employed at slow speeds, offering greater maneuverability and better propulsive efficiency, while BCF movements can achieve greater thrust and accelerations. For both BCF and MPF locomotion, specific swimming modes are identified, based on the propulsor and the type of movements (oscillatory or undulatory) employed for thrust generation. Along with general descriptions and kinematic data, the analytical approaches developed to study each swimming mode are also introduced. Particular reference is made to lunate tail propulsion, undulating fins, and labriform (oscillatory pectoral fin) swimming mechanisms, identified as having the greatest potential for exploitation in artificial systems.

Unsteady Aspects of Aquatic Locomotion

Abstract: Virtually all animals swim unsteadily. They oscillate appendages, undulate, and produce periodic propulsive forces so that the velocity of some part of their bodies changes in time. Because of their unsteady motion, animals experience a fluid force in addition to drag—the acceleration reaction. The acceleration reaction dominates the forces resisting rapid accelerations of animals and may be responsible for generating thrust in oscillating appendages and undulating bodies. The ever-present unsteady nature of animal swimming implies diverse applications of the acceleration reaction.

Transitions from Drag-based to Lift-based Propulsion in Mammalian Swimming

Abstract: Synopsis. The evolution of fully aquatic mammals from quadrupedal, terrestrial mammals was associated with changes in morphology and swimming mode. Drag is minimized by streamlining body shape and appendages. Improvement in speed, thrust production and efficiency is accomplished by a change of swimming mode. Terrestrial and semiaquatic mammals employ drag-based propulsion with paddling appendages, whereas fully aquatic mammals use lift-based propulsion with oscillating hydrofoils. Aerobic efficiencies are low for drag-based swimming, but reach a maximum of 30% for lift-based propulsion. Propulsive efficiency is over 80% for lift-based swimming while only 33% for paddling. In addition to swimming mode, the transition to high performance propul? sion was associated with a shift from surface to submerged swimming providing a reduction in transport costs. The evolution of aquatic mam? mals from terrestrial ancestors required increased swimming performance with minimal compromise to terrestrial movement. Examination of modern analogs to transitional swimming stages suggests that only slight modification to the neuromotor pattern used for terrestrial locomotion is re? quired to allow for a change to lift-based propulsion.

Scaling macroscopic aquatic locomotion

Abstract: Nonlinear inertial flows usually influence the motion of swimming organisms, but most studies focus on the tractable case of swimmers too small to feel such effects. A mechanistic principle now unifies the varied dynamics of macroscopic swimmers. Inertial aquatic swimmers that use undulatory gaits range in length L from a few millimetres to 30 metres, across a wide array of biological taxa. Using elementary hydrodynamic arguments, we uncover a unifying mechanistic principle characterizing their locomotion by deriving a scaling relation that links swimming speed U to body kinematics (tail beat amplitude A and frequency ω) and fluid properties (kinematic viscosity ν). This principle can be simply couched as the power law Re ∼ Swα, where Re = UL/ν ≫ 1 and Sw = ω AL/ν, with α = 4/3 for laminar flows, and α = 1 for turbulent flows. Existing data from over 1,000 measurements on fish, amphibians, larvae, reptiles, mammals and birds, as well as direct numerical simulations are consistent with our scaling. We interpret our results as the consequence of the convergence of aquatic gaits to the performance limits imposed by hydrodynamics.

Kinematic and electromyographic analysis of the functional role of the body axis during terrestrial and aquatic locomotion in the salamander ambystoma tigrinum

Abstract: Summary Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs - one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during the original evolution of terrestriality in early tetrapods.