AsianScientist (Dec. 4, 2018) – Scientists in China and the US have uncovered the underlying mechanisms of the hierarchical structure of whale baleen—the filter-like structure that allows whales to feed on microscopic zooplankton in the oceans. Their findings are published in Advanced Materials.
Baleen consists of a series of parallel plates suspended from the palate and extending down both sides of the mouths of some whales. Taking the place of teeth, baleen withstands a lifetime of forces generated by water flow and prey without fracturing. Fracture toughness, which measures structural integrity for reliable functioning, is a crucial material property for baleen as well as for materials utilized in marine applications.
In the present study, researchers led by Professor Wang Bin from the Shenzhen Institutes of Advanced Technology, China, collaborating with colleagues in the US, found that baleen is made of nanoscale structures consisting of intermediate filaments and mineral crystals embedded in an amorphous matrix.
They found that this arrangement of composite materials increases the overall stiffness and strength of baleen. Furthermore, microscale tubular layers control the direction of crack propagation in the event of fracture, while also limiting the amount of buckling and shearing of baleen under compression.
“Baleen has a highly anisotropic toughness,” said study co-author Professor Sullivan Meyers of the University of California, San Diego.
“In the longitudinal direction, cracks propagate with ease, leading to desirable delamination, fraying and formation of bristles, which are necessary for the filtering action. In the transverse direction, crack propagation is resisted by the tubular structure, providing the required resistance to water flow and prey impact.”
Wang noted that studying baleen from an engineering perspective could shed light on hydration and dynamic loading behavior in materials, which is a key consideration when designing solutions for the marine and maritime environment.
The article can be found at: Wang et al. (2018) Lessons from the Ocean: Whale Baleen Fracture Resistance.
Source: Chinese Academy of Sciences; Photo: Shutterstock.
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