title: Severe Bone Loss as Part of the Life History Strategy of Bowhead Whales.
abstract: The evolution of baleen constituted a major evolutionary change that made it possible for baleen whales to reach enormous body sizes while filter feeding on tiny organisms and migrating over tremendous distances. Bowhead whales (Balaena mysticetus) live in the Arctic where the annual cycle of increasing and decreasing ice cover affects their habitat, prey, and migration. During the nursing period, bowheads grow rapidly; but between weaning and approximately year 5, bowhead whales display sustained baleen and head growth while limiting growth in the rest of their bodies. During this period, they withdraw resources from the skeleton, in particular the ribs, which may lose 40% of bone mass. Such dramatic changes in bones of immature mammals are rare, although fossil cetaceans between 40 and 50 million years ago show an array of rib specializations that include bone loss and are usually interpreted as related to buoyancy control.
authors.affiliation: Department of Wildlife Management, North Slope Borough, Barrow, Alaska, United States of America.
authors.forename: John C
authors.initials: JC
authors.lastname: George
authors.affiliation: Department of Wildlife Management, North Slope Borough, Barrow, Alaska, United States of America.
authors.forename: Raphaela
authors.initials: R
authors.lastname: Stimmelmayr
authors.affiliation: Department of Wildlife Management, North Slope Borough, Barrow, Alaska, United States of America.
authors.forename: Robert
authors.initials: R
authors.lastname: Suydam
authors.affiliation: Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, United States of America.
authors.forename: Sharon
authors.initials: S
authors.lastname: Usip
authors.affiliation: Givens Statistical Solutions LLC, Fort Collins, Colorado, United States of America.
authors.forename: Geof
authors.initials: G
authors.lastname: Givens
authors.affiliation: Department of Wildlife Management, North Slope Borough, Barrow, Alaska, United States of America.
authors.forename: Todd
authors.initials: T
authors.lastname: Sformo
authors.affiliation: Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, United States of America.
authors.forename: J G M
authors.initials: JG
authors.lastname: Thewissen
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000473:pathology*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D050642:Bowhead Whale / Q000254:growth & development*; D007091:Image Processing, Computer-Assisted; D000071421:Life History Traits; D014057:Tomography, X-Ray Computed