The dynamic shear moduli of whale blubber.

Abstract

Blubber is a thick adipose tissue located beneath the dermas. Its viscoelastic properties affect whale tracking tag design, hydrodynamics, and acoustical properties that can be used to study animal behavior and avoid ship strikes. Measure the dynamic shear storage and loss moduli for whale blubber at distances below the dermas for several species. Also, measure the non-collagen and collagen protein content to explore a correlation to viscoelastic properties. Blubber samples were obtained from whale strandings (humpback, sperm, and two gray) in the Pacific Northwest. Shear moduli were measured at oscillation frequencies of 0.31 Hz to 25 Hz using a rotational rheometer. Protein content was measured using a staining protocol. Storage modulus and loss modulus variation with frequency was very consistent across all samples tested. Log-linear and extended polynomials respectively had R-squared values of at least 0.96. Variation of both moduli with depth was fit reasonably well by fourth-order polynomials. Protein content trends varied with species. The samples used in this study were necrotic tissue, however the variation with frequency and to a lesser extent depth was very consistent and may have a broader applicability. Protein content was not found to correlate to moduli values.