No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Extensively remodeled, fractured cetacean tympanic bullae show that whales can survive traumatic injury to the ears
Abstract
Underwater human activities and anthropogenic noise in our oceans may be a major source of habitat degradation for marine life. This issue was highlighted by the opening of the United States Eastern Seaboard for seismic oil and gas exploration in 2014, which generated massive media coverage and widespread concern that seismic surveys could kill or deafen whales. We discovered 11 new specimens of fractured and healed cetacean ear bones, out of a survey of 2127 specimens housed in museum collections. This rare condition has been previously reported only in two specimens of blue whales (Balaenoptera musculus) from the early 1900s, summarized by Fraser & Purves (). All of our new specimens are represented by species for which this condition had never been reported previously, including both baleen and toothed whales. The baleen whale specimens (Balaenoptera physalus, Balaenoptera borealis, Balaenoptera acutorostrata) were collected during Canadian commercial whaling operations in the Atlantic Ocean in the 1970s; the specimens include ear bones with well-healed fractures, demonstrating that baleen whales are capable of overcoming traumatic injury to the ears. The toothed whale specimens (Delphinus sp., Berardius bairdii) were found dead on beaches in 1972 and 2001, respectively, with less remodeled fractures. Thus, ear injuries may be more lethal to the echolocating toothed whales, which rely on hearing for navigation and foraging. We explore several hypotheses regarding how these injuries could have occurred, and conclude that the most parsimonious explanations appear to be both direct and indirect effects of lytic processes from disease or calcium depletion, or damage from external pressure waves. Although further research is required to confirm whether the fractures resulted from natural or human-induced events, this study underscores the importance of museum collections and the work of stranding networks in understanding the potential effects of modern human activities on marine mammal health.
... The presence of traumatic tympanic bullae fractures in whale skulls has also been reported (6). Humans lack tympanic bulla, but fractures affecting the tympanic region of the temporal bone are much more common and well-described in the literature. ...
... There have been only a very few reports describing traumatic tympanic bulla fractures in the veterinary literature (4)(5)(6). To the author's knowledge, there is only one case reported of traumatic tympanic bulla fracture in the cat (5), which lacks the case follow up and only use plain x-rays as diagnostic imaging test. ...
A nine-year-old male European shorthair cat was referred to our practice with severe head trauma after suffering a road traffic accident (RTA). The patient presented marked facial swelling and multiple skin wounds and bruising, inspiratory dyspnea, palpable mandibular and maxillary fractures, serosanguinolent oronasal discharge and right eye exophthalmos and buphthalmos with loss of menace and pupillary reflex. After stabilizing the patient, a CT scan was performed under general anesthesia and an oesophagostomy tube was placed. The scan revealed the presence of multiple right tympanic bulla fractures. Multiple mandibular, maxillary, and palatine fractures were also present. The cat underwent surgery. Mandibular symphyseal separation and maxillary fractures were stabilized using intraoral cerclage wire fixation reinforced with composite and the right eye was enucleated. The rest of the fractures were treated conservatively. A CT scan 4 months after the trauma was also performed. At this point, the maxillofacial fractures were healing properly, and a bone callus demonstrating fusion of fragments of the right tympanic bulla was evident. There was absence of abnormal content inside the right tympanic bulla. The patient recovered uneventfully with no neurological deficits. To the author's knowledge this is the first case reporting a traumatic tympanic bulla fracture in the cat with case follow up, and the first case reported using CT as diagnostic imaging test.
... Enfin, la cavité tympanique des cétacés actuels est bordée d'un épais tissu érectile appelé corpus cavernosum tympanicum. Ce corps caverneux permet de compenser les changements de volume d'air, et donc de pression au sein de l'oreille moyenne, lorsque l'animal plonge (Fraser & Purves 1960a ;Fleischer 1978 ;Ketten 1994Ketten , 1997Sassu & Cozzi 2007 ;Cranford et al. 2010 ;Yamato et al. 2016 ;Tubelli et al. 2018). L'oreille interne des néocètes ( Figure I.04).-En ...
La mise en évidence par la biologie moléculaire et par les données paléontologiques de l'appartenance des cétacés au groupe des artiodactyles constitue une des avancées majeures de ces 30 dernières années en mammalogie. Il n'y a cependant pas à l'heure actuelle de consensus quant aux relations phylogénétiques basales des artiodactyles fondées sur des caractères morphologiques et l'histoire évolutive du groupe est de fait, ponctuée de nombreux points d'interrogation. Cette thèse explore une source de caractères phylogénétiques prometteuse : la région auditive (os pétreux, bulle auditive, osselets de l'oreille moyenne, oreille interne) à partir notamment des nouvelles perspectives offertes par l'imagerie µCT Scan. Les principaux objectifs de cette thèse sont (1) de déterminer le signal phylogénétique porté par la région auditive chez les artiodactyles afin d’apporter une nouvelle source de caractères aux analyses et (2) d’explorer le signal écologique porté par les différents éléments de cette région sensorielle dédiée à l’audition (oreille externe, moyenne et canal cochléaire du labyrinthe osseux) et à l’équilibrioception (vestibule et canaux semi-circulaires du labyrinthe osseux). La première partie de cette thèse (I) nous emmène au Togo, où de nombreux restes inédits de la région auditive de « baleines à pattes » (Protocetidae Stromer, 1908) ont été récoltés. D’un point de vu anatomique, ces restes fossiles ont permis de documenter et de décrire pour la première fois le stapes, l’incus et le labyrinthe osseux d’un protocète ; des éléments indispensables pour comprendre leur audition. L’analyse morpho-fonctionnelle indique qu’une audition optimale était probablement possible dans l’air et dans l’eau pour ces cétacés semi-aquatiques. De plus, la morphologie de leur cochlée indique que leur capacité auditive était proche de celle de leurs cousins terrestres et que les spécialisations relatives aux capacités auditives remarquables des cétacés modernes (i.e. sensibilité aux infra- ou ultrasons) se sont opérées après la séparation historique entre les mysticètes et les odontocètes.La deuxième partie de ce travail (II) se concentre sur les origines de l’amphibiose au sein des Cetancodonta, à travers l’étude de plusieurs familles fossiles, connues pour leurs liens étroits au milieu aquatique. L’étude de la région auditive des hippopotamoïdes (Anthracotheriidae + Hippopotamidae), révèle que l’adaptation à un mode de vie semi-aquatique est apparue plusieurs fois, de façon convergente, dans son histoire évolutive et semble d’ailleurs indiquer une origine terrestre pour ce groupe. Quant au raoellidé Indohyus, son complexe pétro-tympanique présente une combinaison de caractères suggérant un certain degré d’adaptation au milieu aquatique, mais l’étude fonctionnelle de sa cochlée indique que ce taxon ne pouvait très probablement pas entendre de façon efficace sous l’eau. Pour finir, le dernier point de cette thèse explore également le potentiel phylogénétique de la région auditive à travers une analyse construite sur des caractères morphologiques du pétreux et du labyrinthe osseux à l’échelle des artiodactyles. Pour la première fois, les résultats de notre analyse concordent avec ceux des analyses moléculaires. Parmi les points les plus notables, le clade des Cetancodonta est bien soutenu par la morphologie du pétreux et la position d’Indohyus suggère fortement que les raoellidés sont des cétacés.Ainsi, la région auditive s’avère être un élément essentiel d’un point de vu phylogénétique et morphofonctionnel. En effet, comme nous avons pu le voir tout au long de cette thèse, lorsque la nature complexe et variée de la région auditive est appréhendée dans son ensemble, elle permet d’inférer l’écologie d’un taxon donné et d’en apprendre davantage sur ses relations de parenté. Par conséquent, la région auditive est encore loin d’avoir dit ses derniers mots... et nous n’avons pas encore fini d’en entendre parler.
... The capybaras are large animals, possessing a considerably lower predatory pressure compared to small rodents, which can make the detection of hazards and communication between animals in dry environments less important. In addition, they are rodents of semi-aquatic habits, and the characteristics of sound propagation in water, more rapid and important for low-frequency waves, as well as a higher water pressure imposed, possibly influence the morphology of the auditory apparatus to present smaller tympanic bullae as reported for aquatic animals as whales (Reidenberg, 2007;Yamato, Khidas, Pyenson, Fordyce, & Mead, 2016). ...
The capybaras (Hydrochoerus hydrochaeris) are the largest rodent found throughout South America and are present in almost all the Brazilian territory, however, still lack basic descriptions about the species, such as about their cranial anatomy. This study was carried out to investigate the anatomical features in the capybara skull. Eight skulls and two heads, without sexual distinction, were used for the osteological, radiographic and tomographic identification of their structures. The skull of the capybara could be divided into a neurocranium and a viscerocranium. The capybara had a more robust and rectangular skull, elongated face caudally, thinned in the nasal region and slightly convex in the parietal region. The zygomatic arch was expanded and wide, the orbit had a circular shape, the infraorbital foramen was well developed, external acoustic meatus and tympanic bulla were relatively small, and the paracondylar process was large. These anatomical characteristics are compatible with the eating habit and semi‐aquatic life of capybaras, which can be compared with characteristics reported for animals of similar habits. The radiographic image allowed to identify structures such as the frontal sinus, whereas 3D tomographic reconstruction was essential to have a spatial view of the skull of the capybara.
Selected hypermineralized bones (rostrum and tympanic bullae) have yet to be characterized for diverse species of whales (Cetacea). Hypermineralization in these structures is an example of extreme biomineralization that, however, occurs at temperatures around 36 °C. In this study we present the results of analytical investigations of the specimen of tympanic bulla isolated from gray whale (Eschrichtius robustus) for the first time. Examination of the internal surface of the bone mechanically crushed under a press revealed the presence of a lipid-containing phase, which did not disappear even after complete demineralization of the bone material. Additionally, analytical investigations including CARS, ATR-FTIR, Raman and XRD confirmed the presence of carbonated bioapatite and a collagen- lipid complex as the main components of this up to 2.34 kg/cm3 dense bone. Our experimental results open the way for further research on understanding of the principles of hypermineralization in highly specialized whale bones.
Hearing represents the major sense in harbour porpoises (Phocoena phocoena) and impairment of hearing has a great impact on the survival of these animals. In this communication, some anatomical and histological aspects of the tympanoperiotic complex of harbour porpoises are presented. In addition, the ears of 21 incidentally bycaught or stranded freshly dead harbour porpoises of different age groups and sex were investigated histologically. At the entrance to the middle ear cavity, mucosa-associated lymphoid tissue was present that was often hyperplastic in juvenile (9/10) and adult individuals (7/8). Solitary lymphoid follicles were additionally found in the corpus cavernosum and adjacent to the stapedius muscle in single porpoises. The nematode Stenurus minor represented the most common pathogen observed in the middle ear cavity of juvenile and adult harbour porpoises and the parasite was associated with chronic inflammation with metaplastic and hyperplastic epithelial changes. An unusual bone formation at the attachment of the corpus cavernosum to the perioticum was a common finding, even in young individuals. Whether this represents a normal structure or a metaplastic change remains undetermined. Acute haemorrhages in the cochlea and/or the tympanic cavity occurred in all animals and were most likely agonal changes. Single porpoises suffered from purulent otitis media, mycotic otitis media with osteolysis or chronically fractured tympanic bones, likely causing impairment of hearing that may have contributed to by-catch. There was no evidence that stranding in five porpoises was associated with the aural changes. Histological examination of the ears in harbour porpoises is a valuable part of the assessment of their health status. Damage to hearing structures may explain starvation due to impaired ability to catch prey or unusual behaviour such as stranding or entanglement in nets.
Whales receive underwater sounds through a fundamentally different mechanism than their close terrestrial relatives. Instead of hearing through the ear canal, cetaceans hear through specialized fatty tissues leading to an evolutionarily novel feature: an acoustic funnel located anterior to the tympanic aperture. We traced the ontogenetic development of this feature in 56 fetal specimens from 10 different families of toothed (odontocete) and baleen (mysticete) whales, using X-ray computed tomography. We also charted ear ossification patterns through ontogeny to understand the impact of heterochronic developmental processes. We determined that the acoustic funnel arises from a prominent V-shaped structure established early in ontogeny, formed by the malleus and the goniale. In odontocetes, this V-formation develops into a cone-shaped funnel facing anteriorly, directly into intramandibular acoustic fats, which is likely functionally linked to the anterior orientation of sound reception in echolocation. In contrast, the acoustic funnel in balaenopterids rotates laterally, later in fetal development, consistent with a lateral sound reception pathway. Balaenids and several fossil mysticetes retain a somewhat anteriorly oriented acoustic funnel in the mature condition, indicating that a lateral sound reception pathway in balaenopterids may be a recent evolutionary innovation linked to specialized feeding modes, such as lunge-feeding.
Hearing mechanisms in baleen whales (Mysticeti) are essentially unknown but their vocalization frequencies overlap with anthropogenic sound sources. Synthetic audiograms were generated for a fin whale by applying finite element modeling tools to X-ray computed tomography (CT) scans. We CT scanned the head of a small fin whale (Balaenoptera physalus) in a scanner designed for solid-fuel rocket motors. Our computer (finite element) modeling toolkit allowed us to visualize what occurs when sounds interact with the anatomic geometry of the whale's head. Simulations reveal two mechanisms that excite both bony ear complexes, (1) the skull-vibration enabled bone conduction mechanism and (2) a pressure mechanism transmitted through soft tissues. Bone conduction is the predominant mechanism. The mass density of the bony ear complexes and their firmly embedded attachments to the skull are universal across the Mysticeti, suggesting that sound reception mechanisms are similar in all baleen whales. Interactions between incident sound waves and the skull cause deformations that induce motion in each bony ear complex, resulting in best hearing sensitivity for low-frequency sounds. This predominant low-frequency sensitivity has significant implications for assessing mysticete exposure levels to anthropogenic sounds. The din of man-made ocean noise has increased steadily over the past half century. Our results provide valuable data for U.S. regulatory agencies and concerned large-scale industrial users of the ocean environment. This study transforms our understanding of baleen whale hearing and provides a means to predict auditory sensitivity across a broad spectrum of sound frequencies.
Abstract Cetaceans are obligate aquatic mammals derived from terrestrial artiodactyls. The defining characteristic of cetaceans is a thick and dense lip (pachyosteosclerotic involucrum) of an ear bone (the tympanic). This unique feature is absent in modern terrestrial artiodactyls and is suggested to be important in underwater hearing. Here, we investigate the mineralogical and biochemical properties of the involucrum, as these may hold clues to the aquatic adaptations of cetaceans. We compared bioapatites (enamel, dentine, cementum, and skeletal bone) of cetaceans with those of terrestrial artiodactyls and pachyosteosclerotic ribs of manatees (Sirenia). We investigated organic, carbonate, and mineral composition as well as crystal size and crystallinity index. In all studied variables, bioapatites of the cetacean involucrum were intermediate in composition and structure between those of tooth enamel on the one hand and those of dentine, cementum, and skeletal bone on the other. We also studied the amino acid composition of the cetacean involucrum relative to that of other skeletal bone. The central involucrum had low glycine and hydroxyproline concentrations but high concentrations of nonessential amino acids, unlike most bone samples but similar to the tympanic of hippos and the (pachyosteosclerotic) ribs of manatees. These amino acid results are evidence of rapid bone development. We hypothesize that the mineralogical and amino acid composition of cetacean bullae differs from that of other bone because of (1) functional modifications for underwater sound reception and (2) structural adaptations related to rapid ossification.
Perilymph fistula (PLF) is defined as a leak of perilymph at the oval or round window. It excludes other conditions with "fistula" tests due to a dehiscent semi circular canal from cholesteatoma and the superior canal dehiscence syndrome. It was first recognized in the early days of stapedectomy as causing disequilibrium and balance problems before sealing of the stapedectomy with natural tissue became routine. It then became apparent that head trauma and barotraumatic trauma from flying or diving could be a cause of PLF. Descriptions of "spontaneous" PLF with no trauma history followed. A large literature on PLF from all causes accumulated. It became an almost emotional issue in Otolaryngology with "believers" and "nonbelievers." The main criticisms are a lack of reliable symptoms and diagnostic tests and operative traps in reliably distinguishing a perilymph leak from local anaesthetic. There are extensive reviews on the whole topic, invariably conveying the authors' own experiences and their confirmed views on various aspects. However, a close examination reveals a disparity of definitions and assumptions on symptoms, particularly, vestibular. This is an intentionally provocative paper with suggestions on where some progress might be made.
This review considers the effect of anthropogenic sound on beaked whales2. Two major conclusions are presented: (1) gas-bubble disease,induced in supersaturated tissue by a behavioural response to acoustic exposure, is a plausible pathologic mechanism for the morbidity andmortality seen in cetaceans associated with sonar exposure and merits further investigation; and (2) current monitoring and mitigationmethods for beaked whales are ineffective for detecting these animals and protecting them from adverse sound exposure. In addition, fourmajor research priorities, needed to address information gaps on the impacts of sound on beaked whales, are identified: (1) controlledexposure experiments to assess beaked whale responses to known sound stimuli; (2) investigation of physiology, anatomy, pathobiologyand behaviour of beaked whales; (3) assessment of baseline diving behaviour and physiology of beaked whales; and (4) a retrospectivereview of beaked whale strandings
(16) (PDF) Understanding the impacts of anthropogenic sound on beaked whales.. Available from: https://www.researchgate.net/publication/230737956_Understanding_the_impacts_of_anthropogenic_sound_on_beaked_whales [accessed Mar 31 2020].
A number of mass strandings of beaked whales have in recent decades been temporally and spatially coincident with military activities involving the use of midrange sonar. The social behaviour of beaked whales is poorly known, it can be inferred from strandings and some evidence of at-sea sightings. It is believed that some beaked whale species have social organisation at some scale; however most strandings are of individuals, suggesting that they spend at least some part of their life alone. Thus, the occurrence of unusual mass strandings of beaked whales is of particular importance. In contrast to some earlier reports, the most deleterious effect that sonar may have on beaked whales may not be trauma to the auditory system as a direct result of ensonification. Evidence now suggests that the most serious effect is the evolution of gas bubbles in tissues, driven by behaviourally altered dive profiles (e.g. extended surface intervals) or directly from ensonification. It has been predicted that the tissues of beaked whales are supersaturated with nitrogen gas on ascent due to the characteristics of their deep-diving behaviour. The lesions observed in beaked whales that mass stranded in the Canary Islands in 2002 are consistent with, but not diagnostic of, decompression sickness. These lesions included gas and fat emboli and diffuse multiorgan haemorrhage. This review describes what is known about beaked whale anatomy and physiology and discusses mechanisms that may have led to beaked whale mass strandings that were induced by anthropogenic sonar. Beaked whale morphology is illustrated using Cuvier’s beaked whale as the subject of the review. As so little is known about the anatomy and physiology of beaked whales, the morphologies of a relatively well-studied delphinid, the bottlenose dolphin and a well-studied terrestrial mammal, the domestic dog are heavily drawn on.
Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N 2) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N 2 tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest Downloaded from that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N 2 loading to management of the N 2 load. This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.
Sensory systems evolved to allow animals to receive and process information from their surroundings. To understand how sensory systems operate in any given environment, we must understand how the physical characteristics of that environment affect the available information and its propagation and reception. In a very real sense we need to look at both the medium and the message (McLuhan and Fiore 1967). Signals in the marine environment can be substantially different from those in air, and the oceanic medium itself changes the message in a number of ways.
A number of mass strandings of beaked whales have in recent decades been temporally and spatially coincident with military activities involving the use of midrange sonar. The social behaviour of beaked whales is poorly known, it can be inferred from strandings and some evidence of at-sea sightings. It is believed that some beaked whale species have social organisation at some scale; however most strandings are of individuals, suggesting that they spend at least some part of their life alone. Thus, the occurrence of unusual mass strandings of beaked whales is of particular importance. In contrast to some earlier reports, the most deleterious effect that sonar may have on beaked whales may not be trauma to the auditory system as a direct result of ensonification. Evidence now suggests that the most serious effect is the evolution of gas bubbles in tissues, driven by behaviourally altered dive profiles (e.g. extended surface intervals) or directly from ensonification. It has been predicted that the tissues of beaked whales are supersaturated with nitrogen gas on ascent due to the characteristics of their deep-diving behaviour. The lesions observed in beaked whales that mass stranded in the Canary Islands in 2002 are consistent with, but not diagnostic of, decompression sickness. These lesions included gas and fat emboli and diffuse multiorgan haemorrhage. This review describes what is known about beaked whale anatomy and physiology and discusses mechanisms that may have led to beaked whale mass strandings that were induced by anthropogenic sonar. Beaked whale morphology is illustrated using Cuvier’s beaked whale as the subject of the review. As so little is known about the anatomy and physiology of beaked whales, the morphologies of a relatively well-studied delphinid, the bottlenose dolphin and a well-studied terrestrial mammal, the domestic dog are heavily drawn on.
Cetaceans possess highly derived auditory systems adapted for underwater hearing. Odontoceti (toothed whales) are thought to receive sound through specialized fat bodies that contact the tympanoperiotic complex, the bones housing the middle and inner ears. However, sound reception pathways remain unknown in Mysticeti (baleen whales), which have very different cranial anatomies compared to odontocetes. Here, we report a potential fatty sound reception pathway in the minke whale (Balaenoptera acutorostrata), a mysticete of the balaenopterid family. The cephalic anatomy of seven minke whales was investigated using computerized tomography and magnetic resonance imaging, verified through dissections. Findings include a large, well-formed fat body lateral, dorsal, and posterior to the mandibular ramus and lateral to the tympanoperiotic complex. This fat body inserts into the tympanoperiotic complex at the lateral aperture between the tympanic and periotic bones and is in contact with the ossicles. There is also a second, smaller body of fat found within the tympanic bone, which contacts the ossicles as well. This is the first analysis of these fatty tissues' association with the auditory structures in a mysticete, providing anatomical evidence that fatty sound reception pathways may not be a unique feature of odontocete cetaceans.
Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N(2)) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N(2) tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N(2) loading to management of the N(2) load. This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.
Background:
Anatomical comparisons of the ear region of baleen whales (Mysticeti) are provided through detailed osteological descriptions and high-resolution photographs of the petrotympanic complex (tympanic bulla and petrosal bone) of all extant species of mysticete cetaceans. Salient morphological features are illustrated and identified, including overall shape of the bulla, size of the conical process of the bulla, morphology of the promontorium, and the size and shape of the anterior process of the petrosal. We place our comparative osteological observations into a phylogenetic context in order to initiate an exploration into petrotympanic evolution within Mysticeti.
Principal findings:
The morphology of the petrotympanic complex is diagnostic for individual species of baleen whale (e.g., sigmoid and conical processes positioned at midline of bulla in Balaenoptera musculus; confluence of fenestra cochleae and perilymphatic foramen in Eschrichtius robustus), and several mysticete clades are united by derived characteristics. Balaenids and neobalaenids share derived features of the bulla, such as a rhomboid shape and a reduced anterior lobe (swelling) in ventral aspect, and eschrichtiids share derived morphologies of the petrosal with balaenopterids, including loss of a medial promontory groove and dorsomedial elongation of the promontorium. Monophyly of Balaenoidea (Balaenidae and Neobalaenidae) and Balaenopteroidea (Balaenopteridae and Eschrichtiidae) was recovered in phylogenetic analyses utilizing data exclusively from the petrotympanic complex.
Significance:
This study fills a major gap in our knowledge of the complex structures of the mysticete petrotympanic complex, which is an important anatomical region for the interpretation of the evolutionary history of mammals. In addition, we introduce a novel body of phylogenetically informative characters from the ear region of mysticetes. Our detailed anatomical descriptions, illustrations, and comparisons provide valuable data for current and future studies on the phylogenetic relationships, evolution, and auditory physiology of mysticetes and other cetaceans throughout Earth's history.
Global concern over the possible deleterious effects of noise on marine organisms was catalyzed when toothed whales stranded and died in the presence of high intensity sound. The lack of knowledge about mechanisms of hearing in toothed whales prompted our group to study the anatomy and build a finite element model to simulate sound reception in odontocetes. The primary auditory pathway in toothed whales is an evolutionary novelty, compensating for the impedance mismatch experienced by whale ancestors as they moved from hearing in air to hearing in water. The mechanism by which high-frequency vibrations pass from the low density fats of the lower jaw into the dense bones of the auditory apparatus is a key to understanding odontocete hearing. Here we identify a new acoustic portal into the ear complex, the tympanoperiotic complex (TPC) and a plausible mechanism by which sound is transduced into the bony components. We reveal the intact anatomic geometry using CT scanning, and test functional preconceptions using finite element modeling and vibrational analysis. We show that the mandibular fat bodies bifurcate posteriorly, attaching to the TPC in two distinct locations. The smaller branch is an inconspicuous, previously undescribed channel, a cone-shaped fat body that fits into a thin-walled bony funnel just anterior to the sigmoid process of the TPC. The TPC also contains regions of thin translucent bone that define zones of differential flexibility, enabling the TPC to bend in response to sound pressure, thus providing a mechanism for vibrations to pass through the ossicular chain. The techniques used to discover the new acoustic portal in toothed whales, provide a means to decipher auditory filtering, beam formation, impedance matching, and transduction. These tools can also be used to address concerns about the potential deleterious effects of high-intensity sound in a broad spectrum of marine organisms, from whales to fish.
1-98 http://deepblue.lib.umich.edu/bitstream/2027.42/48633/2/ID499.pdf
There are spatial and temporal links between some mass strandings of cetaceans - predominantly beaked whales - and the deployment of military sonar. Here we present evidence of acute and chronic tissue damage in stranded cetaceans that results from the formation in vivo of gas bubbles, challenging the view that these mammals do not suffer decompression sickness. The incidence of such cases during a naval sonar exercise indicates that acoustic factors could be important in the aetiology of bubble-related disease and may call for further environmental regulation of such activity.
The origin of whales (order Cetacea) is one of the best-documented examples of macroevolutionary change in vertebrates. As the earliest whales became obligately marine, all of their organ systems adapted to the new environment. The fossil record indicates that this evolutionary transition took less than 15 million years, and that different organ systems followed different evolutionary trajectories. Here we document the evolutionary changes that took place in the sound transmission mechanism of the outer and middle ear in early whales. Sound transmission mechanisms change early on in whale evolution and pass through a stage (in pakicetids) in which hearing in both air and water is unsophisticated. This intermediate stage is soon abandoned and is replaced (in remingtonocetids and protocetids) by a sound transmission mechanism similar to that in modern toothed whales. The mechanism of these fossil whales lacks sophistication, and still retains some of the key elements that land mammals use to hear airborne sound.
A study of the lesions of beaked whales (BWs) in a recent mass stranding in the Canary Islands following naval exercises provides a possible explanation of the relationship between anthropogenic, acoustic (sonar) activities and the stranding and death of marine mammals. Fourteen BWs were stranded in the Canary Islands close to the site of an international naval exercise (Neo-Tapon 2002) held on 24 September 2002. Strandings began about 4 hours after the onset of midfrequency sonar activity. Eight Cuvier's BWs (Ziphius cavirostris), one Blainville's BW (Mesoplodon densirostris), and one Gervais' BW (Mesoplodon europaeus) were examined postmortem and studied histopathologically. No inflammatory or neoplastic processes were noted, and no pathogens were identified. Macroscopically, whales had severe, diffuse congestion and hemorrhage, especially around the acoustic jaw fat, ears, brain, and kidneys. Gas bubble-associated lesions and fat embolism were observed in the vessels and parenchyma of vital organs. In vivo bubble formation associated with sonar exposure that may have been exacerbated by modified diving behavior caused nitrogen supersaturation above a threshold value normally tolerated by the tissues (as occurs in decompression sickness). Alternatively, the effect that sonar has on tissues that have been supersaturated with nitrogen gas could be such that it lowers the threshold for the expansion of in vivo bubble precursors (gas nuclei). Exclusively or in combination, these mechanisms may enhance and maintain bubble growth or initiate embolism. Severely injured whales died or became stranded and died due to cardiovascular collapse during beaching. The present study demonstrates a new pathologic entity in cetaceans. The syndrome is apparently induced by exposure to mid-frequency sonar signals and particularly affects deep, long-duration, repetitive-diving species like BWs.
Contemporary calcium intakes in the industrialized nations are substantially lower than those to which human physiology is adapted by evolution. As a result, compensatory adjustment is required lifelong. This adjustment consists of high levels of parathyroid activity, leading to parathyroid hyperplasia, high circulating levels of 1,25(OH)(2)D and high bone turnover. The capacity of these compensatory mechanisms to provide sufficient calcium to offset daily losses from the body declines with age; hence, increasingly the body tears down bone to access its calcium. As a result,:the calcium requirement for skeletal maintenance is said to rise with age. Supplemented intakes to a total in the range of 32.5-42.5 mmol (1300-1700 mg)/day have been shown to arrest age-related bone loss and to reduce fracture risk in individuals 65 and older and intakes of 60 mmol (2400 mg), to restore the setting of the parathyroid glands to young adult values. Intakes at such levels also minimize the expression of other disorders such as colon cancer, hypertension and obesity, all of which, while multifactorial, have a calcium deficiency component. Milk, mainly because of constructive interactions among Its several key nutrients, is probably the most nutritionally and cost effective way of meeting the calcium requirement in the elderly.
From crocodiles and penguins to seals and whales, this comprehensive and authoritative synthesis explores the function and evolution of sensory systems in animals whose ancestors lived on land. Together, the contributors explore the dramatic transformation of smell, taste, sight, hearing, balance, mechanoreception, magnetoreception, and electroreception that occurred as lineages of amphibians, reptiles, birds, and mammals returned to aquatic environments. Each chapter integrates data from fields including sensory physiology, anatomy, paleontology, and neurobiology. A one-stop source for information on the sense organs of secondarily aquatic tetrapods, Sensory Evolution on the Threshold sheds new light on both the evolution of aquatic vertebrates and the sensory biology of their astonishing transition.
Identification of Pathological Conditions in Human Skeletal Remains provides an integrated and comprehensive treatment of pathological conditions that affect the human skeleton. There is much that ancient skeletal remains can reveal to the modern orthopaedist, pathologist, forensic anthropologist, and radiologist about the skeletal manifestations of diseases that are rarely encountered in modern medical practice. Beautifully illustrated with over 1,100 photographs and drawings, this book provides essential text and materials on bone pathology, which will improve the diagnostic ability of those interested in human dry bone pathology. It also provides time depth to our understanding of the effect of disease on past human populations.
This reference work is an attempt to provide an integrated and reasonably comprehensive treatnient of pathological conditions that affect the human skeleton. The primary objective is to assist those who conduct research on archeological skeletal remains in interpreting abnormal conditions that they might encounter in the course of their research. However, there is much that ancient skeletal remains can reveal to the modern medical historian, orthopaedist, pathologist, and radiologist about skeletal diseases that are rarely encountered in modern clinical practice. All of the major categories of disease that affect bone are reviewed from the viewpoint of the pathologist. This review is followed by a discussion of the literature on the paleopathology of each condition and the presentation of paleopathological cases thought to represent each of the morbid categories affecting bone. This work is based on extensive individual and collaborative research by both authors on the known parameters of modern skeletal diseases and their expression in antiquity. The monograph provides essential text and illustrative materials on bone pathology, which will improve the diagnostic ability of those interested in human dry bone pathology.
Mead, J. G., and R. E. Fordyce. The Therian Skull: A Lexicon with Emphasis on the Odontocetes. Smithsonian Contributions to Zoology, number 627, 248 pages, frontispiece, 2 diagrams, 32 figures, 9 tables, 2009. — Cetaceans form one of the most unique groups in the evolutionary history of mammals. They have returned to the sea and modified their tail as an efficient means of locomotion. As they adapted to the limited visibility in the aquatic environment, the odontocetes developed a system of echolocation that resulted in extensive modifications to the skull bones. This made descriptive comparisons very difficult and early anatomists unwittingly composed new terms for anatomical structures that had already been named in other taxa. This made anatomical comparisons, based on the literature, extremely tenuous. This lexicon is an attempt to remedy that situation in that it provides headwords and definitions for all the terms that have been used in describing the mammal skull and notes the synonymous terms. The lexicon includes the human nomenclature (Nomina Anatomica), the veterinary nomenclature (Nomina Anatomica Veterinaria) and the nomenclature that is used in descriptive comparative anatomy. The lexicon covers not only extant but extinct mammalian groups and is extensively indexed.
Powerful low‐frequency sounds were recorded from blue whales, Balaenoptera musculus, off the Chilean coast. These three‐part sounds lasted about 36.5 sec, and ranged in frequency from 12.5 to 200 Hz. The sounds occurred in a repetitive pattern that was interrupted as the whale came to the surface to breathe. We estimated that these moanings, in a 14‐ to 222‐Hz band, were 188 dB re 1 μN/m2 (= 88 dB re 1 μbar) at 1 m. They are the most powerful sustained utterances known from whales or any other living source. This finding is especially noteworthy because it is doubtful if these animals, the largest ever to inhabit the earth, will survive man's overharvest.
The histological organization and the main growth trends of the periotic and tympanic bones are described in known-aged common dolphins. The maximum sizes of these bones are already acquired in new-born specimens, and their full mineralization (84.62% and 83.3%, respectively) is reached either at birth (tympanic) or within the first 6 months. Mass, compactness and density of the periotic and tympanic quickly rise during the first year of life, and remain stable afterwards. Mean values of compactness and density observed in adults are 94% and 2.65 g/cm3 for the periotic, and 98% and 2.66 g/cm3 for the tympanic. The periotic and tympanic are composed of a fibro-lamellar tissue, initially deposited as a loose spongiosa with hypermineralized trabeculae. Before the end of the first year, this spongiosa is made compact by the perivascular formation of primary osteons. The vascular network of bone, originally very extensive, is obliterated rapidly by the osteons. The collagen matrix is composed of very thin collagen fibrils (diameter: 10 to 30 nm) arranged in a dramatically reduced network compared to normal bone. Hence, the room available for the mineral phase is considerably increased. Whatever the age of the animals, there is no inner (Haversian) remodelling in the periotic and tympanic. Since the compactness and density of these bones augment during the nursing period, it seems likely that the full hearing capacities of the dolphins are not reached before weaning.
Sound is a primary sensory cue for most marine mammals, and this is especially true for cetaceans. To passively and actively acquire information about their environment, cetaceans have some of the most derived ears of all mammals, capable of sophisticated, sensitive hearing and auditory processing. These capabilities have developed for survival in an underwater world where sound travels five times faster than in air, and where light is quickly attenuated and often limited at depth, at night, and in murky waters. Cetacean auditory evolution has capitalized on the ubiquity of sound cues and the efficiency of underwater acoustic communication. The sense of hearing is central to cetacean sensory ecology, enabling vital behaviours such as locating prey, detecting predators, identifying conspecifics, and navigating. Increasing levels of anthropogenic ocean noise appears to influence many of these activities. Here, we describe the historical progress of investigations on cetacean hearing, with a particular focus on odontocetes and recent advancements. While this broad topic has been studied for several centuries, new technologies in the past two decades have been leveraged to improve our understanding of a wide range of taxa, including some of the most elusive species. This chapter addresses topics including how sounds are received, what sounds are detected, hearing mechanisms for complex acoustic scenes, recent anatomical and physiological studies, the potential impacts of noise, and mysticete hearing. We conclude by identifying emerging research topics and areas which require greater focus.
ABSTRACTA survey of the variation in the eutherian auditory bulla and a consideration of its ontogeny and its possible mode of origin suggests that the basisphenoid bulla of insectivores, the petrosal bulla of primates, and the widely distributed ectotympanic bulla did not represent the condition of the most primitive eutherians. There is also evidence to refute the widely accepted premise that eutherians primitively had a cartilaginous bulla as adults. Instead, this condition is regarded as a secondary specialization derived from a bony entotympanic bulla. The entotympanic bulla was undoubtedly an early, but probably not the earliest, condition in the Eutheria. The contention that the most primitive eutherians lacked a bony or cartilaginous covering of the middle ear cavity ventrally between the petrosal and the nearly horizontal tympanic ring is supported by a number of lines of evidence. The cited existence of an entotympanic in marsupials is regarded as an independent acquisition, parallel with that in eutherians. Evidence is insufficient, in most cases, to determine whether the types of bullae in which an entotympanic is absent evolved through a stage where the latter was present, or arose de novo from the postulated primitive eutherian condition.
According to textbooks, the function of a sneeze is to send a strong blast of air through the nose to remove foreign bodies. Three simple tests are described that show that the current views are wrong. The pressure developed in the mouth/pharynx of the author during a sneeze was recorded as about 135 mmHg reached in about 0.1s. A forced maximal expiration but with the nose and mouth closed produced a nasal secretion although of smaller amount than in the sneeze, in spite of a greater pressure; this is probably because the speed of tension development was much slower than in the sneeze. It is proposed that the high pressure stimulates secretory neurons via branches in the roof of the mouth. The nasal secretion dilutes irritant material in the nose and thus prevents it getting into the lungs.
Mammals are a highly successful group of animals in that they have conquered even the most hostile environments and developed impressive specializations in the process. Some, like the shrews Suncus or Crocidura, weigh only a few grams and are thus smaller than the largest insects. The whales, on the other hand, are millions of times more massive, the blue whale, Balaenoptera musculus, reaching a weight of 100 metric tons and more. Some species, like the Bathyergidae, stay below the ground throughout their life, while others live in the desert, or climb in the mountains, wade through swamps, or even venture out into the open sea without ever returning to the shore. Petaurus, Cynocephalus, as well as a variety of others are gliders and the Chiroptera are all highly skilled flyers, while others, like the antarctic Weddell seal, Leptonychotes, spend most of their time near or under the ice, diving for food. The bats use a sophisticated echo-location system, based on the emission an reception of ultrasonic sounds, as do the dolphins. Mysticetes are capable of communicating over large distances using very low frequences. Last but not least, man owes much of his superiority to the development of language.
Functionally interesting dimensions of the tympano-periotic complex were measured and compared in 18 odontocete and six mysticete species, ranging from small porpoises to the blue whale. We determined (i) the masses of the tympanic and periotic bones (T and P) and of the ossicles malleus, incus, and stapes (M, I and S), (ii) the volume occupied bythe tympanic bone (V), (iii) the areas of the tympanic plate and oval window (A1 and A2), (iv) the thickness of the tympanic plate (D), and (v) the densities of the ossicles (dM, dI, and dS). In most cases, roughly isometric scaling was found in both toothed and baleen whales. P is isometric to T, and the tympanic bone is structurally isometric in all species studied, although not within mysticetes as a group, shown by the isometric relations of V to T, of T(2/3) to A1, and of D to square root(A1). The essentially isometric scaling of the tympanic bone provides a basis for the functional models described by Hemilä et al. (1999). The relation of S to M+I is also isometric, but the relation of M+I+S to T is negatively allometric, as is the relation of A2 to A1, both with slopes close to 2/3. The possible functional implication of this allometry is unknown. The mean ossicular density is 2.64 g/cm3 for odontocetes, and 2.35 g/cm3 for mysticetes. The highly mineralized and convex tympanic plate provides cetaceans with a uniquely large and stiff sound collecting area.
Three rare cases of sudden high frequency sensorineural hearing loss with longitudinal fracture of the stapes footplate are presented. In two patients it occurred after they suppressed a sneeze. In the third patient after the exertion of parturition. At exploratory tympanotomy all were found to have longitudinal fractures of the stapes footplate and two had a perilymph fistula at that site. The history and audiometric profiles in such patients should raise a high index of suspicion regarding the possibility of a stapes footplate fracture.
Contemporary calcium intakes in the industrialized nations are substantially lower than those to which human physiology is adapted by evolution. As a result, compensatory adjustment is required lifelong. This adjustment consists of high levels of parathyroid activity, leading to parathyroid hyperplasia, high circulating levels of 1,25(OH)2D and high bone turnover. The capacity of these compensatory mechanisms to provide sufficient calcium to offset daily losses from the body declines with age; hence, increasingly the body tears down bone to access its calcium. As a result, the calcium requirement for skeletal maintenance is said to rise with age. Supplemented intakes to a total in the range of 32.5-42.5 mmol (1300-1700 mg)/day have been shown to arrest age-related bone loss and to reduce fracture risk in individuals 65 and older and intakes of 60 mmol (2400 mg), to restore the setting of the parathyroid glands to young adult values. Intakes at such levels also minimize the expression of other disorders such as colon cancer, hypertension and obesity, all of which, while multifactorial, have a calcium deficiency component. Milk, mainly because of constructive interactions among its several key nutrients, is probably the most nutritionally and cost effective way of meeting the calcium requirement in the elderly.
One hundred temporal bones obtained from forensic autopsies were dissected to expose injured structures. Longitudinal fractures were present in 82%, transverse fractures in 11%, and mixed fractures in 7% of the cases. Facial canal injuries were present in almost half of the bones with longitudinal fractures (36/82), although cuts of the facial nerve stem were rarely encountered. Damages to the facial canal associated with longitudinal fractures were most frequently seen in the region of the geniculum. However, transverse fractures with facial canal involvement (7/11) most frequently occurred in the labyrinthine portion, causing a complete cut of the facial nerve. Injuries to the jugular bulb were also common (21/100) and associated with all types of temporal bone fractures. Observed damages to the auditory ossicles included disconnection of their joints or fractures of the malleus or stapes. Fractures of the incus were not observed. Injuries to the carotid canal were common (52/100), although an injury to the arterial wall was observed in only one specimen. The frequency and nature of damage in temporal bone fractures strictly reflect the type of fracture, especially in terms of facial nerve disorders: the most serious damage is observed with fractures that involve the otic capsule.
A majority of investigations on primary blast injuries have focused on gas-containing organs, while the likelihood of blast-induced neurotrauma remains underrated. In Norway minke whales (Balaenoptera acutorostrata) are hunted using small fishing boats rigged with harpoon guns, which fire harpoons tipped with a grenade containing a charge of 30-g penthrite. The grenade detonates 60-70 cm inside the animal. The present study was undertaken to characterize the neuropathological changes caused by the penthrite blast and evaluate its role in the loss of consciousness and death in hunted whales. The study included 37 minke whales that were examined shipboard. The brains were later subjected to gross and light microscopy examination. The results showed that intra-body detonation of the grenade in near vicinity of the brain resulted in trauma similar to severe traumatic brain injury associated with a direct blow to the head. Detonation in more distant areas of the body resulted in injuries resembling acceleration-induced diffuse traumatic brain injury. The authors conclude that even if several vital organs were fatally injured in most whales, the neurotrauma induced by the blast-generated pressure waves were the primary cause for the immediate or very rapid loss of consciousness and death.