Whisker Shape and Orientation Help Seals and Sea Lions Minimize Self-Noise

While it doesn’t always pay to take the path of least resistance, sometimes it’s best to just go with the flow. New research on seal and sea lion whiskers help explain how they are adapted to do just that.

Whiskers, more technically known as vibrissae, provide their owners with important sensory information about the world around them. The follicle of each whisker is connected to many nerves, allowing an animal to “feel” its surroundings by picking up tiny vibrations in air or water. Sea lions (pictured left) and seals (right), like land mammals, are equipped with a highly sensitive array of whiskers that allows them to detect disturbances from afar or zero in on the wake of their next meal. A new study published in PLOS ONE explores the characteristics of seal and sea lion whiskers that make them particularly well-suited to underwater signal detection.

Researchers at the University of Florida investigated the hydrodynamic properties — the natural properties of liquids in motion — of whiskers from three different pinniped species: harbor seals, northern elephant seals, and California sea lions. Using CT scanning, researchers precisely measured the shape of each species’ whiskers.  While the cross sections of whiskers in land mammals are almost perfectly circular, seal and sea lion whiskers are somewhat flattened, in the shape of an oval. In this study, the researchers ran water currents over the pinniped whiskers at different angles, watched how the whiskers responded, and, measured the amount of whisker vibration at different orientations relative to the current.

The orientation of the whiskers, it turns out, affects how much they vibrate. The authors found that when the skinny edge of the whisker angled into the flow of water, the whisker vibrated far less than when the flat side faced the current.


The authors suggest that the flat shape of each whisker and its resting orientation — specifically, skinny side angled into the flow of water — may minimize the amount of self-induced whisker vibration generated by normal, forward swimming (video). The reduced base-level “whisker noise” may help whiskered marine mammals better detect important vibrations in the water, caused by the environment and nearby animals. And that, really, is what the whiskers are there for in the first place.

Citation: Murphy CT, Eberhardt WC, Calhoun BH, Mann KA, et al. (2013) Effect of Angle on Flow-Induced Vibrations of Pinniped Vibrissae. PLoS ONE 8(7): e69872. doi:10.1371/journal.pone.0069872

Image: Image comes from Figure 5 of the manuscript

Announcing the World Register of Marine Species Collection


The ocean teems with millions of plants, animals and other organisms, and keeping track of this vast inventory can be quite a laborious task. Since its launch in 2008 as an affiliated project with the Census of Marine Life, the World Register of Marine Species (WoRMS) has been working to consolidate taxonomic information from over a hundred databases to provide an open-access, comprehensive inventory of names and descriptions of all marine organisms.

Today we are pleased to announce the launch of the PLOS ONE WoRMS Collection, comprising of 14 species reviews from this long-term project.

The WoRMS database contains species names, synonyms, sources and a range of other information, as described in the collection overview. The reviews included in the WoRMS collection discuss some of the species represented by the database, such as sea squirts, brittle stars, lace corals, crustaceans, reptiles and more, and highlight the diversity across the globe of just some of the many species within the register.

This collection aims to join PLOS ONE’s quest for open-access data content and the WoRMS’s pursuit of recording and continuously updating an entire database of the world’s marine species for this purpose.

To read more about this collection, please visit: PLOS Collections: The World Register of Marine Species (2013)

Image Credit: Johnsen et al. (2009)