scholarly journals A faster escape does not enhance survival in zebrafish larvae

2017 ◽  
Vol 284 (1852) ◽  
pp. 20170359 ◽  
Author(s):  
Arjun Nair ◽  
Christy Nguyen ◽  
Matthew J. McHenry
Keyword(s):  
High Speed ◽  
Larval Fish ◽  
Body Position ◽  
Three Dimensional ◽  
Limited Range ◽  
The Body ◽  
Model Parameters ◽  
Fish Prey ◽  
Zebrafish Larvae ◽  
Fish Predators

An escape response is a rapid manoeuvre used by prey to evade predators. Performing this manoeuvre at greater speed, in a favourable direction, or from a longer distance have been hypothesized to enhance the survival of prey, but these ideas are difficult to test experimentally. We examined how prey survival depends on escape kinematics through a novel combination of experimentation and mathematical modelling. This approach focused on zebrafish ( Danio rerio ) larvae under predation by adults and juveniles of the same species. High-speed three-dimensional kinematics were used to track the body position of prey and predator and to determine the probability of behavioural actions by both fish. These measurements provided the basis for an agent-based probabilistic model that simulated the trajectories of the animals. Predictions of survivorship by this model were found by Monte Carlo simulations to agree with our observations and we examined how these predictions varied by changing individual model parameters. Contrary to expectation, we found that survival may not be improved by increasing the speed or altering the direction of the escape. Rather, zebrafish larvae operate with sufficiently high locomotor performance due to the relatively slow approach and limited range of suction feeding by fish predators. We did find that survival was enhanced when prey responded from a greater distance. This is an ability that depends on the capacity of the visual and lateral line systems to detect a looming threat. Therefore, performance in sensing, and not locomotion, is decisive for improving the survival of larval fish prey. These results offer a framework for understanding the evolution of predator–prey strategy that may inform prey survival in a broad diversity of animals.

scholarly journals Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

2016 ◽  
Vol 13 (116) ◽  
pp. 20160068 ◽  
Author(s):  
Gen Li ◽  
Ulrike K. Müller ◽  
Johan L. van Leeuwen ◽  
Hao Liu
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Bony Fish ◽  
The Body ◽  
Functional Explanation ◽  
Image Velocimetry ◽  
Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

Simplified Triped Robot for Analysis of Three-Dimensional Gait Generation

2017 ◽  
Vol 29 (3) ◽  
pp. 528-535
Author(s):  
Yoichi Masuda ◽  
◽  
Masato Ishikawa
Keyword(s):  
High Speed ◽  
Force Feedback ◽  
Three Dimensional ◽  
Radial Symmetry ◽  
The Body ◽  
Walking Robots ◽  
Body Structure ◽  
Gait Patterns ◽  
Gait Generation ◽  
Proposed Model

[abstFig src='/00290003/08.jpg' width='230' text='The tripedal robot “Martian petit”' ] Significant efforts to simplify the body structure of multi-legged walking robots have been made over the years. Of these, the Spring-Loaded-Inverted-Pendulum (SLIP) model has been very popular, therefore widely employed in the design of walking robots. In this paper, we develop a SLIP-based tripedal walking robot with a focus on the geometric symmetry of the body structure. The proposed robot possesses a compact, light-weight, and compliant leg modules. These modules are controlled by a distributed control law that consists of decoupled oscillators with only local force feedback. As demonstrated through experiments, the simplified design of the robot makes possible the generation of high-speed dynamic locomotion. Despite the structural simplicity of the proposed model, the generation of several gait-patterns is demonstrated. The proposed minimalistic design approach with radial symmetry simplifies the function of each limb in the three-dimensional gait generation of the robot.

scholarly journals ARTIFICIAL NEURAL NETWORKS BASED SLEEP MOTION RECOGNITION USING NIGHT VISION CAMERAS

2004 ◽  
Vol 16 (02) ◽  
pp. 79-86 ◽  
Author(s):  
CHUNG-HSIEN KUO ◽  
FANG-CHUNG YANG ◽  
MING-YUAN TSAI ◽  
MING-YIH LEE
Keyword(s):  
Neural Networks ◽  
High Speed ◽  
Body Position ◽  
Body Movement ◽  
The Body ◽  
Night Vision ◽  
Ann Model ◽  
Motion Recognition ◽  
Video Frames ◽  
Artificial Neural

The body movement is one of the most important factors to evaluate the sleep quality. In general, the sleep motion is hardly investigated, and it must take a long time to observe the motion of the patient in terms of a pre-recoded video storage media with high speed playing. This paper proposes an image-based solution to recognize the sleep motions. We use the contact free and IR-based night vision camera to capture the video frames during the sleep of the patient. The video frames are used to recognize the body positions and the body directions such as the “body up”, “body down”, “body right”, and “body left”. In addition to the image processing, the proposed artificial neural network (ANN) sleep motion recognition solution is composed of two neural networks. These two neural networks are organized as in a cascade configuration. The first ANN model is used to identify the body position features from the images; and the follower ANN model is constructed based on the features that are identified by the first ANN model to recognize the body direction. Finally, the implementations and the practical results of this work are all illustrated in this paper.

scholarly journals Countershading enhances camouflage by reducing prey contrast

2020 ◽  
Vol 287 (1927) ◽  
pp. 20200477
Author(s):  
Callum G. Donohue ◽  
Jan M. Hemmi ◽  
Jennifer L. Kelley
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
Luminance Contrast ◽  
The Body ◽  
Body Parts ◽  
Live Fish ◽  
Average Luminance ◽  
Fish Predators ◽  
Dimensional Shape ◽  
Three Dimensional Shape

A three-dimensional body shape is problematic for camouflage because overhead lighting produces a luminance gradient across the body's surface. Countershading, a form of patterning where animals are darkest on their uppermost surface, is thought to counteract this luminance gradient and enhance concealment, but the mechanisms of protection remain unclear. Surprisingly, no study has examined how countershading alters prey contrast, or investigated how the presence of a dorsoventral luminance gradient affects detection under controlled viewing conditions. It has also been suggested that the direction of the dorsoventral luminance gradient (darkest or lightest on top) may interfere with predators' abilities to resolve prey's three-dimensional shape, yet this intriguing idea has never been tested. We used live fish predators (western rainbowfish, Melanotaenia australis ) and computer-generated prey images to compare the detectability of uniformly pigmented (i.e. non-countershaded) prey with that of optimally countershaded prey of varying contrasts against the background. Optimally countershaded prey were difficult for predators to detect, and the probability and speed of detection depended on prey luminance contrast with the background. In comparison, non-countershaded prey were always highly detectable, even though their average luminance closely matched the luminance of the background. Our findings suggest that uniformly pigmented three-dimensional prey are highly conspicuous to predators because overhead lighting increases luminance contrast between different body parts or between the body and the background. We found no evidence for the notion that countershading interferes with predator perception of three-dimensional form.

Simple mechanisms organise orientation of escape swimming in embryos and hatchling tadpoles of Xenopus laevis

2000 ◽  
Vol 203 (12) ◽  
pp. 1869-1885 ◽  
Author(s):  
A. Roberts ◽  
N.A. Hill ◽  
R. Hicks
Keyword(s):  
Mathematical Model ◽  
Xenopus Laevis ◽  
High Speed ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
The Body ◽  
Video Recordings ◽  
Stage Of Development ◽  
Physical Features ◽  
Neutrally Buoyant

Many amphibian tadpoles hatch and swim before their inner ears and sense of spatial orientation differentiate. We describe upward and downward swimming responses in hatchling Xenopus laevis tadpoles from stages 32 to 37/38 in which the body rotates about its longitudinal axis. Tadpoles are heavier than water and, if touched while lying on the substratum, they reliably swim upwards, often in a tight spiral. This response has been observed using stroboscopic photography and high-speed video recordings. The sense of the spiral is not fixed for individual tadpoles. In ‘more horizontal swimming’ (i.e. in directions within +/−30 degrees of the horizontal), the tadpoles usually swim belly-down, but this position is not a prerequisite for subsequent upward spiral swimming. Newly hatched tadpoles spend 99 % of their time hanging tail-down from mucus secreted by a cement gland on the head. When suspended in mid-water by a mucus strand, tadpoles from stage 31 to 37/38 tend to swim spirally down when touched on the head and up when touched on the tail. The three-dimensional swimming paths of stage 33/34 tadpoles were plotted using simultaneous video images recorded from the side and from above. Tadpoles spiralled for 70 % of the swimming time, and the probability of spiralling increased to 1 as swim path angles became more vertical. Tadpoles were neutrally buoyant in Percoll/water mixtures at 1.05 g cm(−)(3), in which anaesthetised tadpoles floated belly-down and head-up at 30 degrees. In water, their centre of mass was ventral to the muscles in the yolk mass. A simple mathematical model suggests that the orientation of tadpoles during swimming is governed by the action of two torques, one of which raises the head (i.e. increases the pitch) and the other rotates (rolls) the body. Consequently, tadpoles (i) swim belly-down when the body is approximately horizontal because the body is ballasted by dense yolk, and (ii) swim spirally at more vertical orientations when the ballasting no longer stabilises orientation. Measurements in tethered tadpoles show that dorsal body flexion, which could produce a dorsal pitch torque, is present during swimming and increases with tailbeat frequency. We discuss how much of the tadpole's behaviour can be explained by our mathematical model and suggest that, at this stage of development, oriented swimming responses may depend on simple touch reflexes, the organisation of the muscles and physical features of the body, rather than on vestibular reflexes.

scholarly journals The impact of pelvic lateral rotation on hindlimb kinematics and stride length in the red-legged running frog, Kassina maculata

2019 ◽  
Vol 6 (5) ◽  
pp. 190060 ◽  
Author(s):  
Amber J. Collings ◽  
Laura B. Porro ◽  
Cameron Hill ◽  
Christopher T. Richards
Keyword(s):  
High Speed ◽  
Stride Length ◽  
Reference Frames ◽  
Comparative Anatomy ◽  
Three Dimensional ◽  
Video Data ◽  
The Body ◽  
Kinematic Models ◽  
Lateral Rotation ◽  
The Impact

Some frog species, such as Kassina maculata (red-legged running frog), use an asynchronous walking/running gait as their primary locomotor mode. Prior comparative anatomy work has suggested that lateral rotation of the pelvis improves walking performance by increasing hindlimb stride length; however, this hypothesis has never been tested. Using non-invasive methods, experimental high-speed video data collected from eight animals were used to create two three-dimensional kinematic models. These models, each fixed to alternative local anatomical reference frames, were used to investigate the hypothesis that lateral rotation of the mobile ilio-sacral joint in the anuran pelvis plays a propulsive role in walking locomotion by increasing hindlimb stride length. All frogs used a walking gait (duty factor greater than 0.5) despite travelling over a range of speeds (0.04–0.23 m s −1 ). The hindlimb joint motions throughout a single stride were temporally synchronized with lateral rotation of the pelvis. The pelvis itself, on average, underwent an angular excursion of 12.71° (±4.39°) with respect to the body midline during lateral rotation. However, comparison between our two kinematic models demonstrated that lateral rotation of the pelvis only increases the cranio-caudal excursion of the hindlimb modestly. Thus, we propose that pelvic lateral rotation is not a stride length augmenting mechanism in K. maculata .

scholarly journals Three-dimensional simulation for fast forward flight of a calliope hummingbird

2016 ◽  
Vol 3 (6) ◽  
pp. 160230 ◽  
Author(s):  
Jialei Song ◽  
Bret W. Tobalske ◽  
Donald R. Powers ◽  
Tyson L. Hedrick ◽  
Haoxiang Luo
Keyword(s):  
Immersed Boundary Method ◽  
High Speed ◽  
Computational Study ◽  
Three Dimensional ◽  
The Body ◽  
Immersed Boundary ◽  
Forward Flight ◽  
Advance Ratio ◽  
Dimensional Simulation ◽  
Thrust Production

We present a computational study of flapping-wing aerodynamics of a calliope hummingbird ( Selasphorus calliope ) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s −1 . The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome drag on the body, and such thrust production comes at price of negative lift induced during upstroke. This feature might be shared with bats, while being distinct from insects and other birds, including closely related swifts.

scholarly journals Body Configuration in Multiple Somersault High Bar Dismounts

1990 ◽  
Vol 6 (2) ◽  
pp. 147-156 ◽  
Author(s):  
David G. Kerwin ◽  
Maurice R. Yeadon ◽  
Sung-Cheol Lee
Keyword(s):  
Angular Momentum ◽  
Simulation Model ◽  
Olympic Games ◽  
Body Position ◽  
Three Dimensional ◽  
The Body ◽  
Abduction Angle ◽  
Successful Completion ◽  
Dimensional Simulation

An 11-segment three-dimensional simulation model was used to modify the body configurations of eight gymnasts performing multiple somersault dismounts during the Men’s High Bar competition in the 1988 Seoul Olympic Games. Four layout double somersault performances were modified to change a characteristic backward arch to a straight body position. This modification reduced the somersault rotation by 0.03 to 0.10 somersaults. Four tucked triple somersault performances were modified so that the thigh abduction angle was reduced to zero. This modification resulted in underrotations ranging from 0.01 to 0.34 somersaults depending on the amount of thigh abduction in the original movement. The additional angular momentum needed for successful completion of the modified movements was small in general and in no case greater than 13%.

scholarly journals Biomechanical factor affecting Baseball Pitching Velocity

2019 ◽  
Author(s):  
Yasushi Ota ◽  
Ryoga Kuriyama
Keyword(s):  
High Speed ◽  
Time Series Data ◽  
Three Dimensional ◽  
The Body ◽  
Lower Limbs ◽  
Whole Body ◽  
Series Data ◽  
Physical Factors ◽  
Body Parts ◽  
Joint Force

In baseball, pitchers have a central role and high-speed pitching is desirable. So far, several studies of the physical factors related to pitching form with the aim of improving the speed of pitched balls have been conducted. In this study, we used a motion capture to acquire three-dimensional (3D) time series data related to the speed of pitched balls and performed a kinetics analysis by using these acquired data. The acquired data were divided into five pitching phases: wind up, early cocking, late cocking, acceleration, and follow through. Our analysis identified the body parts that contribute to increasing the speed of pitched balls, i.e., the speed of rotation of individual joints and the timing/phase when power can be applied. Especially, by examining joint angular velocity and joint force, we showed that the speed of pitched balls is determined by the action of the upper limbs as well as the coordinated action of the whole body, particularly the lower limbs and the trunk.

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