Suffused: baleen fringe mat porosity and hydrodynamics in balaenid and balaenopterid whales
Abstract Baleen plates of filter-feeding whales are longitudinally fibrous, separating where eroded medially into mats of fringes due to friction from water, prey, and the tongue. The fringes end up spreading-out, in other words suffusing, over the comb-like structure of the baleen assemblage. This...
| Published in: | Biological Journal of the Linnean Society |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Oxford University Press (OUP)
2024
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1093/biolinnean/blae030 https://academic.oup.com/biolinnean/advance-article-pdf/doi/10.1093/biolinnean/blae030/57272947/blae030.pdf |
| Summary: | Abstract Baleen plates of filter-feeding whales are longitudinally fibrous, separating where eroded medially into mats of fringes due to friction from water, prey, and the tongue. The fringes end up spreading-out, in other words suffusing, over the comb-like structure of the baleen assemblage. This study examined the relationships between mat morphology and the hydrodynamics it generates. Samples collected from nine rack locations on a bowhead whale (Balaena mysticetus) and fin whale (Balaenoptera physalus) were investigated with a new technique of mat porosity determination in a flume setting. Porosity was measured in the range of 5–20% and 8–37% in the bowhead and fin whale samples respectively. These were largest ventrally in both species, while remaining somewhat insensitive to the flume’s water speed. A new hydrodynamical model of the through-mat currents was used to estimate speeds of 0.15–3.0 cm/s and mat permeabilities of the order of 10−13 m2, depending on the applied pressure. Finally, and relative to samples collected near the entrance of the mouth, these trends were quantitatively similar in both species. With tongue- and flow-based erosion as the main mechanism for mat creation in all extant mysticetes, our analysis suggests baleen-generated filtration as having emerged early in their evolution. |
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