Which seals have the stiffest whiskers?

Pinnipeds (for example seals) tend to have vibrissae (i.e. whiskers) of varying flexurality (stiffness), arranged in a mystacial (moustache-like) format. Warranting an experimental investigation:

“This is the first comparative study on the mechanical properties of pinniped mystacial vibrissae.”

– explain a team of researchers from Texas A&M university and West Chester University, US. Seal-Whisker-Test
The investigators mechanically tested [see photo] the whiskers of Gray seals, Harbor seals, Harp seals, Ringed seals, Spotted seals, Weddell seals, Bearded seals, California sea lions, Guadalupe fur seals, Northern fur seals and South American fur seals as cantilever beams, in order to gauge their flexural stiffness (when both wet and dry). Finding that Fur seals’ whiskers had the largest flexural stiffness and Gray seals’ the lowest.

“We suggest that the variation in flexural stiffness in pinniped vibrissae results in variation in resonance frequencies of hair shafts that interact with the beaded morphology to provide a greater resolution of hydrodynamic reception in phocid seals with beaded vibrissae.”

The team also note the opportunities for further research, suggesting that seals’ rhinal vibrissae (nose hairs) and superciliary vibrissae (eyebrows) might also warrant investigation.

See: Ginter Summarell CC, Ingole S, Fish FE, Marshall CD (2015) Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae. PLoS ONE 10(7): e0127941.

Also see: Growth rates of whiskers: Seals vs Sea Lions