Chapter 10 - Postcranial skeleton and musculature
forelimb; myology; Bowhead whale; muscles; skeleton; Balaena mysticetus; hindlimb;
The postcranial skeleton of bowhead whales was described in detail more than 100 years ago. The musculature of bowheads has not been studied in detail but matches that of other mysticetes in general features. In this chapter, we focus on some aspects of the skeleton that differs from that of other cetaceans. First, the skeleton of bowheads changes with ontogenetic age. Some of these changes are gross-morphologically, while others are biochemical and histological. Several are related to the life history of the species. Our discussion focuses on the changes in the morphology of the cervical vertebral column, the ontogenetic variation in carpals, and the variation in the hind limb. Individuals with external hind limbs occur infrequently, but there is a great variation in the size of ox coxae, femur, and tibia.
Thewissen JGM; Hillmann DJ; George JC; Tarpley RJ; Sheffield Gay; Stimmelmayr R; Suydam RS
The Bowhead Whale
2021
2021-01-01
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1016/B978-0-12-818969-6.00010-8" target="_blank" rel="noreferrer noopener"></a>
Chapter 8 - Prenatal development
Bowhead whale; fetus; Balaena mysticetus; embryo; gestation; heterochrony
The prenatal development of bowhead whales is poorly known, and no complete ontogenetic series exist. However, the available embryos and fetuses elucidate aspects of the development of the species, as well as that of all of mysticetes in general, and demonstrate the role of heterochrony in development. For instance, hair on the face of bowhead whale embryos develops at the same ontogenetic stage as it does in terrestrial mammals, even though body hair never develops. The absence of teeth characterizes all modern baleen whales, but bowhead whale fetuses initiate teeth around the same time as land mammals, to then resorb them in the fetal period. Baleen forms after that, late in the fetal period.
Thewissen JGM; Hillmann DJ; George JC; Stimmelmayr R; Tarpley RJ; Sheffield Gay; Suydam RS
The Bowhead Whale
2021
2021-01-01
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1016/B978-0-12-818969-6.00008-X" target="_blank" rel="noreferrer noopener"></a>
Paleontological and Developmental Evidence for the Origin of Baleen and the Loss of Teeth in Baleen Whales
Biochemistry & Molecular Biology; Cell Biology; Life Sciences & Biomedicine - Other; Topics
Thewissen J G M; Hieronymus T L; George J C; Suydam R; Stimmelmayr R; McBurney D
Faseb Journal
2017
2017-04
Journal Article
n/a
Age estimation in bowhead whales using tympanic bulla histology and baleen isotopes
Arctic; Balaena; Balaena mysticetus; bone; carbon; corpora; GLGs; growth; LAGs; layers; Marine & Freshwater Biology; minke whales; stable isotopes; tympanic bulla; Zoology
Tympanic bullae and baleen plates from bowhead whales of the Western Arctic population were examined. Growth layer groups (GLGs) in the involucrum of the tympanic bone were used to estimate age of the whales, and compared to stable isotope signatures along transects of baleen plates and the involucrum. The involucrum of the tympanic bone consists of three regions that form in utero, during nursing in the first year, and during the first decades of life, respectively. Life history events, such as annual migration, are recorded in the bowhead tympanic bulla. It is likely that bone growth in the bowhead tympanic occurs during periods of high food intake, while slow or arrested growth occurs during periods of low food intake. Comparisons between numbers of GLGs in the tympanic, number of isotopic oscillations in a baleen plate, length of the baleen plate, and total whale length show correlation coefficients as high as 0.97. The tympanic GLG method is particularly useful for estimating the age of whales up to 20 yr old.
Sensor J D; George J C; Clementz M T; Lovano D M; Waugh D A; Givens G H; Suydam R; Stimmelmayr R; Thewissen J G M
Marine Mammal Science
2018
2018-04
Journal Article
<a href="http://doi.org/10.1111/mms.12476" target="_blank" rel="noreferrer noopener">10.1111/mms.12476</a>
An analysis of von Economo neurons in the cerebral cortex of cetaceans, artiodactyls, and perissodactyls
Anatomy & Morphology; anterior cingulate cortex; bowhead whale; brain; cetartiodactyla; Cingulate; cortex; Cortical evolution; evolution; evolution; Fork cells; frontoinsular cortex; great apes; Insula; Neurosciences & Neurology; phylogeny; spindle neurons; variant frontotemporal dementia; Von Economo neurons (VENs); whale
Von Economo neurons (VENs) are specialized projection neurons with a characteristic spindle-shaped soma and thick basal and apical dendrites. VENs have been described in restricted cortical regions, with their most frequent appearance in layers III and V of the anterior cingulate cortex, anterior insula, and frontopolar cortex of humans, great apes, macaque monkeys, elephants, and some cetaceans. Recently, a ubiquitous distribution of VENs was reported in various cortical areas in the pygmy hippopotamus, one of the closest living relatives of cetaceans. That finding suggested that VENs might not be unique to only a few species that possess enlarged brains. In the present analysis, we assessed the phylogenetic distribution of VENs within species representative of the superordinal clade that includes cetartiodactyls and perissodactyls, as well as afrotherians. In addition, the distribution of fork cells that are often found in close proximity to VENs was also assessed. Nissl-stained sections from the frontal pole, anterior cingulate cortex, anterior insula, and occipital pole of bowhead whale, cow, sheep, deer, horse, pig, rock hyrax, and human were examined using stereologic methods to quantify VENs and fork cells within layer V of all four cortical regions. VENs and fork cells were found in each of the species examined here with species-specific differences in distributions and densities. The present results demonstrated that VENs and fork cells were not restricted to highly encephalized or socially complex species, and their repeated emergence among distantly related species seems to represent convergent evolution of specialized pyramidal neurons. The widespread phylogenetic presence of VENs and fork cells indicates that these neuron morphologies readily emerged in response to selective forces,whose variety and nature are yet to be identified.
Raghanti M A; Spurlock L B; Treichler F R; Weigel S E; Stimmelmayr R; Butti C; Thewissen Jgmh; Hof P R
Brain Structure & Function
2015
2015-07
Journal Article
<a href="http://doi.org/10.1007/s00429-014-0792-y" target="_blank" rel="noreferrer noopener">10.1007/s00429-014-0792-y</a>
Role of Desmosomes in the Annual Molting of the External Acoustic Meatus Lining of the Bowhead Whale (Balaena mysticetus): A Preliminary Study
Zoology
Rehorek S J; Stimmelmayr R; George J C; Suydam R; McBurney D M; Thewissen J G M
Integrative and Comparative Biology
2019
2019-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
n/a