Swimming of larval zebrafish: ontogeny of body waves and implications for locomotory development

Abstract

SUMMARY Fish larvae, like most adult fish, undulate their bodies to propel themselves. A detailed kinematic study of the larval body wave is a prerequisite to formulate a set of functional requirements that the locomotor system must fulfil to generate the observed swimming kinematics. Lateral displacement and curvature profiles were obtained for zebrafish (Danio rerio) larvae at 2–21 days post-fertilisation for three swimming behaviours (cyclic swimming, slow starts and fast startle responses) using high-speed video. During cyclic swimming, fish larvae maintain tail beat frequencies of up to 100 Hz. The corresponding longitudinal strains, estimated from the peak curvatures of the midline, reach up to 0.19 in superficial tissue. The strain rate can reach 120 s–1. The wave of curvature travels along the body at a near-constant rate. Posterior to the stiff head, body-lengthspecific curvature is high and rises gently along the entire trunk to a maximum value of 6. Burst-and-coast swimming generates similar peak curvatures to cyclic swimming, but curvature rises more steeply from head to tail. Fish larvae exhibit phase shifts of 57–63°between the wave of lateral displacement and the wave of curvature, resulting in a 1:1.2 ratio of body wave length to curvature wave length. During C-starts, muscle strain can reach 0.19 and superficial longitudinal strain rates approach 30 s–1. Fish larvae do not initiate their escape response with a standing wave of curvature, although their C-starts approach a standing wave as the larvae grow older. The performance demands derived from swimming kinematics suggest that larval axial muscles have very short contraction cycles (10 ms), experience considerable strains (up to 0.2)and strain rates (up to 30 s–1 in white muscle fibres) yet are able to power swimming for several seconds.

Hydrodynamic starvation in first-feeding larval fishes

“…Differences in feeding rates and feeding success of larvae could be attributed to the effect of size on the immediate hydrodynamic regime. However, these differences could also be attributed to ontogenetic changes in fin, mouth, bone, and/or eye morphologies, all of which bear functional implications regarding the ability to swim, detect prey, and maneuver (3,8,9,(11)(12)(13)(14). We separated the relative contribution to size on feeding rates from other ontogenetic effects by conducting a series of dynamic-scaling experiments.…”

“…10). In larval fishes, this transition was shown to affect fundamental biological processes, such as respiration, metabolism, and swimming (11)(12)(13)(14). Like many adult fishes, larval fish capture their prey using "suction feeding" ( Fig.…”

Escape trajectories are deflected when fish larvae intercept their own C-start wake

“…By the end of stage 2 at 24 ms, the heading angles were reduced to 888 and 818 in the experiment and the simulation, respectively (figure 3d). During the following stroke (third tail beat), both experimental and computational fish again reversed heading, turning clockwise, with the heading angle peaking at 33 ms, and reaching a final escape speed of 19 l s 21 and a heading angle of 1008 at the end of the sequence. As illustrated in figure 3a, the CoM trajectories of the computational and the experimental fish were similar, but the computational fish was shifted to the left and covered a slightly smaller distance.…”

“…A typical C-start comprises at least two stages (stage 1 and 2), which can be roughly defined by the tail beat, with stage 1 defined by the first tail beat to one side, bending the fish into a C shape, and stage 2 defined by the second tail beat to the other side while the fish accelerates along its new path of motion [17][18][19][20][21][22]. Fish shed a vortex ring at the end of stage 1 and stage 2.…”

Physiological study of larval fishes: challenges and opportunities

“…Batty and Blaxter, 1992). Lateral displacement and curvature profiles can be created from the video recordings, enabling further evaluation of swimming kinematics (Müller and van Leeuwen, 2004). Examination of muscle function following acute or chronic exposure to environmental factors such as temperature (Martell and Kieffer, 2007), hypoxia (Matschak et al, 1995), and water velocity can indicate the extent to which muscle morphology and function can be altered in development.…”