Data from: How do baleen whales stow their filter? A comparative biomechanical analysis of baleen bending

Bowhead and right whale (balaenid) baleen filtering plates, longer in
vertical dimension (3-4+ m) than the closed mouth, presumably bend during
gape closure. This has not been observed in live whales, even with
scrutiny of videorecorded feeding sequences. To determine what happens to
baleen as gape closes, we conducted an integrative, multifactorial study
including materials testing, functional (flow tank and kinematic) testing,
and histological examination. We measured baleen bending properties along
the dorsoventral length of plates and anteroposterior location within a
rack of plates via mechanical (axial bending, composite flexure,
compression, and tension) tests of hydrated and air-dried tissue samples
from balaenid and other whale baleen. Balaenid baleen is remarkably strong
yet pliable, with ductile fringes and low stiffness and high elasticity
when wet; it likely bends in the closed mouth when not used for
filtration. Calculation of flexural modulus from stress/strain experiments
shows baleen is slightly more flexible where it emerges from the gums and
at its ventral terminus, but kinematic analysis indicates plates bend
evenly along their whole length. Fin and humpback whale baleen has similar
material properties but less flexibility, with no dorsoventral variation.
Internal horn tubes have greater external and hollow luminal diameter but
lower density in lateral relative to medial baleen of bowhead and fin
whales, suggesting greater capacity for lateral bending. Baleen bending
has major consequences not only for feeding morphology and energetics but
also conservation given that entanglement in fishing gear is a leading
cause of whale mortality.