Fig 1.
S. rhinocerous and S. angustiporus individuals.
(A) A S. rhinocerous individual, and (B) a 3-D digital model of a S. rhinocerous specimen. (C) A S. angustiporus individual, and (D) a 3-D digital model of a S. angustiporus specimen.
Fig 2.
Superficial neuromasts distribution of S. rhinocerous.
The yellow dots are the superficial neuromasts obtained by DASPEI stain. The upper two photographs show a dorsal view and the lower two show a side view of the S. rhinocerous.
Fig 3.
Schematic depicting the experimental and analysis steps in Experiments 1 and 2 with free-swimming fish and the CFD modeling using models created by scanning preserved specimens. Gray boxes show the final response variables used in analyses.
Fig 4.
Schematic drawing of the camera tracking and recording setup used in laboratory experiments.
The trajectory tracking system consisted of three cameras, Cameras 1 and 2 (Canon 80D, 50Hz) and Camera 3 (10HZ), a PIV Laser (200HZ), and two controllers and two computers (Dell XPS13).
Table 1.
List of symbols.
Fig 5.
(A) Trajectory of S. rhinocerous projected into a horizontal plane during one trial for, 0–0.5 hour, 0.5–1 hour, 1–1.5 hours, 1.5–2 hours from onset of experiment. (B) Frequency distributions of the distance to a wall (black line) and swimming speed (red line) for the same four time bins.
Fig 6.
Swimming speed (u) versus time taken from a series of images during Experiment 2. This illustrates a burst-and-coast swimming style.
Fig 7.
(A) Reciprocal speed during the coasting phase of swimming; (B) Fish drag coefficient estimates obtained by measurements of swimming speeds (red) and by CFD modeling (blue) for analyses in this paper and reported by others. The red star indicates the median value derived for S. rhinocerous from Experiment 2, and the box delineates the 25th and 75th percentiles. The blue stars and circles are from the CFD simulations for S. rhinocerous and S. angustiporus, respectively. The red curve is a regressive fit to all the CFD results from this study.
Fig 8.
(A) Kinetic energy of flow (EL) at the laser plane and fish swimming speed (uL) in the three stages (approaching, entering, exiting laser plane) for a series of Experiment 2. The sensing distance D is the distance between the fish and the laser plane; (B) Maximum sensing distance (DL) versus fish swimming speed (uL) showing concurrent (uL, DL) pairs; (C) showing representative water flow fields for a moment (M1, M2 and M3) within each of the stages.
Fig 9.
Canal neuromasts distribution and pressure simulation.
The putative canal pores distribution along the fish body and CFD results showing pressure distributions of S. rhinocerous and S. angustiporus from our simulations (Re = 1280), canal pores are approximately shown as black dots with white outlines, supraorbital canal (so), supratemporal canal (sc), trunk canal (tc).
Fig 10.
Lateral line stimulus estimation.
CFD results showing (A) the normalized pressure, or Cp, and (B) ΔCp values along the assumed line of canal neuromasts for the simulations. Results extracted from earlier studies are also included. The Y-axis is plotted with its scale reversed (decreasing values).