Biology subjects

Lauder, G. V.

Publications and source records attributed to Lauder, G. V..

5 recordsLinked to original sources

bioRxiv2026

Fluctuating hydrodynamic forces increase fish locomotor variability in turbulence

Turbulence has been shown to alter fish locomotion and increase the energetic cost of swimming, yet the mechanisms underlying these effects remain unclear. To address this, we studied giant danios (Devario aequipinnatus) swimming at multiple speeds in both laminar and turbulent flows. Within this turbulent regime, mean tail-beat kinematics were largely unchanged relative to laminar conditions, but cycle-to-cycle variability increased, with larger effects occurring at higher speeds, where the velocity fluctuations are stronger. Turbulence also increased the frequency of asymmetric tail beats, particularly under stronger fluctuations, providing further evidence of increased locomotor variability. A quasi-steady hydrodynamic model suggests that velocity fluctuations in this flow regime produce relatively small changes in mean thrust and drag, whereas thrust variance scales with the square of velocity fluctuation magnitude. These variable forces likely prompt fish to adjust locomotor output to maintain position, which could explain the observed increase in kinematic variability. We further show that mechanical swimming power can be increased through correlations between fluctuating hydrodynamic forces and tail velocity. Together, these results suggest a mechanistic link between turbulent velocity fluctuations, locomotor variability, and increased energy expenditure.

biophysics↗

bioRxiv2025

Fish locomotor variation: connecting energetics and kinematic modulation

Analyses of vertebrate locomotion have frequently revealed variations in locomotor energetics and movement both among individuals and through time within an individual. This variation is often collapsed into mean values for broad comparative analyses of function. However, kinematic patterns of locomotion, even when animals move at a near-constant mean speed, frequently vary with both the physical and biological context. Here we demonstrate, using analyses of fish locomotion and energetics, how variation among individuals in kinematic gaits can manifest as changes in dynamics of metabolic rate (estimated from oxygen uptake). We present kinematic data from a small school of giant danio (Devario aequipinnatus) to show that fish within a school frequently modulate their kinematics and change position, even when the school moves at an overall constant mean speed. We show that rainbow trout (Oncorhynchus mykiss), swimming over a range of speeds, exhibit considerable variation in tail beat frequency and metabolic rate among speeds. By experimentally altering the fluid dynamic environment, we demonstrate that brook trout (Salvelinus fontinalis) show correlated modulation of both kinematics and metabolic rate. Simultaneous measurement of energetic and biomechanical characteristics can unveil the physiological, biomechanical, and fluid dynamic mechanisms that underlie dynamic changes in vertebrate locomotor gaits.

physiology↗

bioRxiv2025

The tail of myliobatid rays controls body stability

Eagle rays, pelagic eagle rays, cownose rays, and manta rays are the only four batoid families exhibiting oscillatory locomotion, and are characterized by expanded pectoral fins and long, slender tails that can exceed body length. This study investigates whether these tails influence body stability during gliding, when the pectoral fins remain extended and held in position. We first measured relative tail lengths across the four families (Rhinopteridae, Myliobatidae, Aetobatidae, and Mobulidae). Using two 3D-printed models based on a myliobatid body and a NACA 0012 shape, we tested the effects of different tail lengths (double, equal to disc width, and no tail) on posture and stability across increasing flow speeds (1-4.5 body lengths/second) in a recirculating flow tank. Pitch, roll, and ODBA were recorded via an embedded accelerometer. Our results show that tail length varies among myliobatids, with spotted eagle rays having the longest tails (>4x body length) and giant manta rays the shortest ([~]0.9x body length). Models without tails exhibited greater instability, particularly increased roll and ODBA. However, tails longer than body length did not provide additional stability or affect pitch. Although tails offered similar results in both models, the tailless NACA model was more unstable at high speeds than the manta body model. We propose that elongate tails of myliobatids enhance stability by generating hydrodynamic drag and exerting a restoring moment around the center of gravity, thereby damping body oscillations. Tails exceeding 0.9x body length may serve additional functions such as communication, mating, or sensory roles. SUMMARY STATEMENTWhat is the function of the long and slender tail in myliobatid rays? We show experimentally that a tail longer than one body length greatly increases hydrodynamic stability during gliding.

zoology↗

bioRxiv2023

Locomotor effects of a fibrosis-based immune response in stickleback fish

The vertebrate immune system provides an impressively effective defense against parasites and pathogens. However, these benefits must be balanced against a range of costly side-effects including energy loss and risks of auto-immunity. These costs might include biomechanical impairment of movement, but little is known about the intersection between immunity and biomechanics. Here, we show that a fibrosis immune response in threespine stickleback (Gasterosteus aculeatus) has collateral effects on their locomotion. When freshwater stickleback are infected with the tapeworm parasite Schistocephalus solidus, they face an array of fitness consequences ranging from impaired body condition and fertility to an increased risk of mortality. To fight the infection, some stickleback will initiate a fibrosis immune response in which they produce excess collagenous tissue in their coelom. Although fibrosis is effective at reducing infection, some populations of stickleback actively suppress this immune response, possibly because the costs of fibrosis outweigh the benefits. Here we quantify the locomotor effects of the fibrosis immune response in the absence of parasites to investigate whether there are collateral costs of fibrosis that could help explain why some fish forego this effective defense. To do this, we induce fibrosis in stickleback and then test their C-start escape performance. Additionally, we measure the severity of fibrosis, body stiffness, and body curvature during the escape response. We were able to estimate performance costs of fibrosis by including these variables as intermediates in a structural equation model. This model reveals that among control fish without fibrosis, there is a performance cost associated with increased body stiffness. However, fish with fibrosis did not experience this cost but rather displayed increased performance with higher fibrosis severity. This result demonstrates that the adaptive landscape of immune responses can be complex with the potential for wide reaching and unexpected fitness consequences.

evolutionary biology↗

bioRxiv2020

The fish body functions as an airfoil: surface pressures generate thrust during carangiform locomotion

The anterior body of many fishes is shaped like an airfoil turned on its side. With an oscillating angle to the swimming direction, such an airfoil experiences negative pressure due to both its shape and pitching movements. This negative pressure acts as thrust forces on the anterior body. Here, we apply a high-resolution, pressure-based approach to describe how two fishes, bluegill sunfish (Lepomis macrochirus Rafinesque) and brook trout (Salvelinus fontinalis Mitchill), swimming in the carangiform mode, the most common fish swimming mode, generate thrust on their anterior bodies using leading-edge suction mechanics, much like an airfoil. These mechanics contrast with those previously reported in lampreys - anguilliform swimmers - which produce thrust with negative pressure but do so through undulatory mechanics. The thrust produced on the anterior body of these carangiform swimmers through negative pressure comprises 28% of the total thrust produced over the body and caudal fin, substantially decreasing the net drag on the anterior body. On the posterior region, subtle differences in body shape and kinematics allow trout to produce more thrust than bluegill, suggesting that they may swim more effectively. Despite the large phylogenetic distance between these species, and differences near the tail, the pressure profiles around the anterior body are similar. We suggest that such airfoil-like mechanics are highly efficient, because they require very little movement and therefore relatively little active muscular energy, and may be used by a wide range of fishes since many species have appropriately-shaped bodies. Significance StatementMany fishes have bodies shaped like a low-drag airfoil, with a rounded leading edge and a smoothly tapered trailing region, and move like an airfoil pitching at a small angle. This shape reduces drag but its significance for thrust production by fishes has not been investigated experimentally. By quantifying body surface pressures and forces during swimming, we find that the anterior body shape and movement allows fishes to produce thrust in the same way as an oscillating airfoil. This work helps us to understand how the streamlined body shape of fishes contributes, not only to reducing drag, but also directly to propulsion, and, by quantitatively linking form and function, leads to a more complete understanding fish evolution and ecology.

physiology↗