PMC

The linear‐threshold model fitted to coordinate values of landmarks and represented AIC in each age group (a) All spotted seal, (b) Male of the spotted seal, (c) Female of the spotted seal, (d) All harbor seal, (e) Male of the harbor seal, (f) Female of the harbor seal)

Phocids and their undulating whiskers. (a) Schematic of a seal tracking its prey by following the vortices left behind in the wake street. Schematic of seal adapted from ColoringAll.com. Copyright © 2021 ColoringAll.com. (b) Arrangement of the array of whiskers on the muzzle of a harbour seal. Adapted from []. Copyright © 1995 The Company of Biologists. (c) Harbour seal and (d) grey seal. Seal photographs courtesy of the Zeehondencentrum (Pieterburen, The Netherlands) and reproduced with permission. (e) Optical micrograph showing undulations in grey and harbour seal whiskers along the wider edge of the whiskers.

a Weber fractions of the South African fur seal for the tested standard time intervals (STIs) from 0.2 s to 7 s in closed chamber/low ambient light (filled triangles) and from 3 s to 12 s in open chamber/high ambient light (open triangles). b Weber fractions of the harbour seal for the STIs from 0.1 s to 30 s. The timing data for STIs 3 s to 30 s were
adopted from Heinrich et al. (). c Weber fractions of the harbour seal for the tested STIs from 0.1 s to 1.6 s and of the South African fur seal for STI from 0.2 s to 1.6 s (closed chamber/low ambient light). d Weber fractions for the harbour seal and the South African fur seal in the time range in which a constant relationship between Weber fraction and standard time interval can be found, i.e. in which Weber’s law holds. Please note that for this comparison, the fur seal data obtained in closed chamber /low ambient light were taken which does not include a difference threshold for a STI of 12 s. Difference thresholds for STIs of 18 s and 30 s were only determined for the harbour seal. The data of the harbour seal are generally depicted with filled circles, the data of the fur seal with triangles

The macroscopic morphology of the seal fin. (a) The original seal fin; (b) the seal fin with only radial rub; (c,e,g,i) the axial rub sides of the seal fins at 60, 80, 100, and 120 μm/s respectively; (d,f,h,j) the non-axial rub sides of the seal fins at 60, 80, 100, and 120 μm/s respectively; (k) the observed surface.