Splitting Hairs: Biomechanics of Gray Whale (Eschrichtius robustus) Baleen
College
College of Sciences
Department
Biological Sciences
Graduate Level
Master’s
Presentation Type
Oral Presentation
Abstract
Rorqual whales (Mysticetes, Cetacea) use baleen, a filtration structure attached to the upper jaw, to retain prey from water during filter feeding. Baleen is the general term used for the keratin filter of all mysticetes, and refers to the complete structure of the Zwischensubstanz, connective papillae, major baleen plates, minor baleen plates, and baleen fringes. Rorquals lunge filter-feed, engulfing enormous masses of both prey and water. Gray whales (Eschrichtius robustus) use a unique method of suction filter-feeding, in addition to lunge filter-feeding. Gray whales scrape their heads and baleen against the substrate, fluidizing mud and sand to suck in their prey. Gray whale baleen must endure repeated collisions with rough substrate, while withstanding the forces of gallons of prey and water. To better understand the deformation of gray whale baleen, we recorded morphological measurements and performed three-point bend tests to record max load values on baleen plates from 18 gray whales in four demographics categories: male adults, female adults, male subadults, and female subadults. We found significant morphometric differences (p < 0.001) in plate length, plate width, plate fringe diameter, plate lingual thickness, major spacing and minor spacing between the groups. The strongest factor in separating the baleen from one group to another was flexural stiffness (EI), which was consistently higher in male adults than in other demographic groups. Differences in the morphological and material of baleen properties point to variance in behavior and function throughout a gray whale’s lifespan. Future investigation into how the location of a baleen plate in the mouth (anterior/posterior, right/left) relates to its material function may demonstrate behavioral and functional differences in a single individual.
Keywords
Gray whale, Baleen, Flexural stiffness, Allometry
Splitting Hairs: Biomechanics of Gray Whale (Eschrichtius robustus) Baleen
Rorqual whales (Mysticetes, Cetacea) use baleen, a filtration structure attached to the upper jaw, to retain prey from water during filter feeding. Baleen is the general term used for the keratin filter of all mysticetes, and refers to the complete structure of the Zwischensubstanz, connective papillae, major baleen plates, minor baleen plates, and baleen fringes. Rorquals lunge filter-feed, engulfing enormous masses of both prey and water. Gray whales (Eschrichtius robustus) use a unique method of suction filter-feeding, in addition to lunge filter-feeding. Gray whales scrape their heads and baleen against the substrate, fluidizing mud and sand to suck in their prey. Gray whale baleen must endure repeated collisions with rough substrate, while withstanding the forces of gallons of prey and water. To better understand the deformation of gray whale baleen, we recorded morphological measurements and performed three-point bend tests to record max load values on baleen plates from 18 gray whales in four demographics categories: male adults, female adults, male subadults, and female subadults. We found significant morphometric differences (p < 0.001) in plate length, plate width, plate fringe diameter, plate lingual thickness, major spacing and minor spacing between the groups. The strongest factor in separating the baleen from one group to another was flexural stiffness (EI), which was consistently higher in male adults than in other demographic groups. Differences in the morphological and material of baleen properties point to variance in behavior and function throughout a gray whale’s lifespan. Future investigation into how the location of a baleen plate in the mouth (anterior/posterior, right/left) relates to its material function may demonstrate behavioral and functional differences in a single individual.