[MARMAM] New paper on baleen structure and properties in the Southern right and Pygmy right whales

Carolina Loch Silva lochcarolina at gmail.com
Fri Jul 10 18:13:53 PDT 2020

Dear MARMAM subscribers,

My co-authors and I are pleased to announce the following paper in the *Journal
of the Mechanical Behavior of Biomedical Materials*:

*Structure and properties of baleen in the Southern right (Eubalaena
australis) and Pygmy right whales (Caperea marginata)*

Carolina Loch, Shaun Vaz Viegas, J. Neil Waddell, Catherine Kemper, Richard
B. Cook and Alexander J. Werth



Baleen is a resilient and keratinised filter-feeding structure attached to
the maxilla of mysticete whales. It is strong and tough, yet a pliant and
resilient material, that withstands extreme pressures in the oral cavity
during feeding. We investigated the structure, water content, wettability
and mechanical properties of baleen of the Southern right (SRW) and Pygmy
right whales (PRW), to understand the effects of hydration on the physical
and mechanical properties of baleen. Sixty 25 × 15mm baleen subsamples were
prepared from one individual of SRW and PRW. Half were hydrated in
circulated natural seawater for 21 days and half were dry. Water content
analysis showed that SRW baleen was 21.2% water weight and PRW was 26.1%.
Wettability testing indicated that surfaces of both hydrated and dried SRW
and PRW baleen were hydrophilic, with hydrated samples of both species
having lower contact angle values. For the SRW, the average contact angle
of hydrated baleen was 40° ± 13.2 and 73° ± 6 for dried samples. Hydrated
PRW baleen had an average contact angle of 44° ± 15.3, which was lower than
in dried samples (74° ± 2.9). Three-point bending mechanical tests showed
that the average maximum flexural stress of dried SRW (134.1 ± 34.3 MPa)
and PRW samples (117.8 ± 22.3 MPa) were significantly higher than those of
hydrated SRW (25.7 ± 6.3 MPa) and PRW (19.7 ± 4.8 MPa) baleen. Scanning
electron microscope images showed the stratification of the outer cortical
layer, with cross-linked keratin fibres observed within and between baleen
keratin sheets. Hydrated baleen, as in its natural and functional
behaviour, has greater flexibility and strength, attributes necessary for
the complex filter feeding mechanism characteristic of whales. Hydration
must be considered when addressing the physical and mechanical properties
of baleen, especially when using dried museum specimens.

Full text is available at:

Or alternatively, a *pdf* can be requested at: carolina.loch at otago.ac.nz

Best regards,


Carolina Loch Silva, PhD

Senior Lecturer in Oral Biology

Department of Oral Sciences

Sir John Walsh Research Institute

Faculty of Dentistry, University of Otago

Dunedin 9054, New Zealand

Phone: +(64) 03 479-9255

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